How to use your blood sugar as a fuel gauge for weight loss and blood sugar control

Intermittent fasting has helped many people lose weight, lower their blood sugar, and reverse Type 2 Diabetes without the hassle of tracking their food. But, sadly, for many others, fasting doesn’t provide the results they hoped for.

When we get ravenously hungry after not eating for an extended period, most of us tend to reach for energy-dense, nutrient-poor foods that quickly undo all the benefits of our restriction and hard work. 

So, to ensure you achieve long-term success, you need to find the minimum effective dose of fasting that gives you the results you want without pushing your body so hard that it rebels and leaves you trapped in an endless restrict-binge cycle.

When it comes to fasting, as with many other things in life, more is not always better. The challenge is finding a way to apply just enough restriction to ensure you move towards your goal at a sustainable pace.

With Data-Driven Fasting, you will ‘gamify‘ the fat loss process with a few simple measurements to ensure you continue to move forward over the long term.  By measuring the things that matter, you can optimise your eating schedule to ‘bio-hack’ the outcome you want.

Data-Driven Fasting has proved to be a powerful tool to lose fat and optimise blood sugar levels without tracking calories or following a rigid schedule.  We have been thrilled with the results from the thousands of people who have tried it!  To learn more about Data-Driven Fasting, read on!

The Data-Driven Fasting 30 Day Challenge 

The Data-Driven Fasting 30 Day-Challenge is a structured approach to optimise your intermittent fasting to align with your goals, preferences and routine.

Over the 30 days, you will learn to optimise your health, gain control of your blood sugars and ensure healthy body fat levels to give you the best chance for a long, healthy and vibrant life!

The Data-Driven Fasting 30-Day Challenge will guide you through the process of optimising your fasting routine, including:

  • Baselining – Identify Your Current Trigger that you will use to identify genuine hunger and when you need to eat to refuel.
  • Your current foods/meals – Learn how the foods you currently eat affect your blood sugar – which ones leave you satisfied and which ones lead you to eat more than your body requires.
  • Hunger training – Learn to delay eating until your blood sugar is below Your Current Trigger to make sure that you eat only when you need to refuel. This will ensure that you are lowering your blood sugars and burning body fat.
  • Curb your late-night binging – Use your waking blood sugars to identify if you are eating too late.
  • Main Meal vs Discretionary Meals – Identify the Main Meal you will use to anchor your eating routine and ensure you get enough nutrients. Based on Your Current Trigger, you can then treat the others as Discretionary Meals to meet your energy needs as required.
  • Optimise your eating routine – Lock in your new habits to guarantee you are moving towards your goals.

What you will get:

  • 30-day program to guide you to optimise YOUR fasting routine to ensure you achieve your goals.
  • The Data-Driven Fasting app to track your progress and fine-tune your intermittent fasting routine.
  • 130-page manual complete with detailed instructions and answers to 99 frequently asked questions.
  • A workbook that you can use to reflect on your learning during the challenge.
  • Weekly Live Q&A sessions where you can ask all your questions.

Best of all, we get to do this in an interactive community forum where you can share your journey and ask lots of questions.  

We can’t wait to get started on 6 March 2021!

You can join up now at

Is calorie counting the best way to lose weight?

Many people try calorie counting apps or trackers, but the vast majority find it unsustainable.  

Most of us live unpredictable lives with events like family dinners, work lunches and impromptu parties that make it impractical to weigh and measure everything we eat.  So, although we can be disciplined most of the time, it’s those occasional meals (when your calorie tracking app isn’t looking) that usually undo all the hard work.

Even if you were able to weigh and measure everything you ate, the data in your app doesn’t precisely match the foods you are eating. Your body doesn’t ‘burn’ the food the same way that calories are measured in a bomb calorimeter (i.e. the machine used to measure the calories in food, pictured below).

Calorie tracking apps also don’t account for the thermic effect of food, which changes depending on the macronutrient profile of your food and the degree of processing.  So, any calorie target from an online calculator is always going to be an inaccurate estimate, no matter how much time we spend trying to get it perfect.   

Your metabolism is incredibly complex.  The number of calories (energy) you require is influenced by a range of factors including your muscle mass, exercise, stress and sleep.  Your energy expenditure naturally changes from day to day, and your energy needs also change.  

Eating is impulsive and instinctual. A healthy appetite ensures you seek out the nutrients you need, which means that – despite our best efforts to limit the amount we eat – our appetite usually wins out in the end.  

If you try to maintain a fixed calorie intake, there is a real risk that your healthy appetite signals will become dysregulated as you try to ignore genuine hunger on some days and overeat on others.

Further, when you suddenly slash your energy intake, your body quickly adapts to ensure you survive.  Your metabolic rate slows; you produce less heat; you feel less energetic, and your involuntary activity will reduce so you will burn less energy.  

So, while energy is always conserved, the factors on either side of the calories in vs calories out equation are incredibly complicated and beyond our ability to manage accurately (even with the latest fitness trackers and apps). 

When you limit calories in (i.e. eat less), the part of your brain that looks after your instincts (the ‘Reptilian Brain’, see picture below) will be alerted to what it perceives as a threat of starvation. The Reptilian Brain responds to this ’emergency’ by driving up hunger and slowing your metabolism.  While we like to think our conscious brain is in control and that we can use our willpower to eat less and move more, the majority of people don’t succeed over the long term.  Eventually, your ‘lizard brain’ steps in to take control to ensure you survive.  

Counting calories may cause disordered eating 

If you’ve ever tried tracking calories, you will know that your lizard brain doesn’t like to relinquish control of your appetite to a smartphone app. Many people become anxious when they put so much effort into tracking everything they eat and don’t get the results they hoped for.  Sadly, food tracking can drive an unhealthy neurosis in many people. 

A 2017 study of people with a diagnosed eating disorder found that 75% of participants reported using the MyFitnessPal app. Disturbingly, 73% of the MyFitnessPal users said that their use of the app had contributed to their eating disorder.  

Simply counting calories and trying to stay under some arbitrary target can be a recipe of disaster for many people.  The simple message to ‘eat less’ and ‘move more’, leads many people to fall into a cycle of bingeing and restricting their food intake.  

Our natural hunger signals are strongly influenced by factors in our modern food environment, including:

  • an abundance of highly processed foods that are a combination of refined carbohydrates and fats together (which tend to drive us to eat more than we really need to);
  • 24/7 food availability all year round;
  • cultural cues that lead us to associate food with fun, affection, pleasure, social gatherings and popularity (rather than providing nutrients and sufficient energy);
  • food advertising and marketing that promotes snacking and eating; and
  • artificial colourings and flavours that trick your appetite into believing processed food products contain nutrients.

Each of these factors contributes to an unnatural food environment, which leads to overeating and weight gain.

What is the best fasting schedule for you?  

While fasting continues to grow in popularity, there is still plenty of confusion about the ideal routine.  Is it:

So many people are passionate about their favourite fasting routine that that has worked wonders for them. But,

  • How do you know which one is right for you?
  • How do you know if it’s working?
  • How can you fine-tune your routine to ensure you continue to get results?
  • How do you make sure the schedule won’t lead you to binge and undo all your hard work?
  • What if you feel ravenously hungry, but it’s not ‘time to eat’ yet according to the approach that you happen to have chosen?

Why does fasting fail for so many people?

There are plenty of people who fast for days but are still not lean.  It’s not that difficult to do a multi-day fast, especially if they are carrying a lot of excess body fat.  You may have seen people feeling fantastic as they brag to everyone on Facebook about their high ketone levels after days of not eating.  But there are also plenty of people in the same fasting groups complaining about not making long-term progress as they lose and regain the same few pounds over and over again, often with worsening body composition (i.e. more fat and less muscle).  

Many fasting programs and schedules promote the idea of ‘building your fasting muscle’ by simply using more will power to fast for longer and longer.  The problem is that many people who try fasting according to a pre-determined schedule or program will awaken their Reptilian Brain and issues arise when it comes to ‘breaking’ there fast and ‘refeeding’.  

After going without food for a few days, most people don’t reach for the grilled chicken breast and broccoli.  When we feel ravenously hungry, we gravitate toward highly processed, energy-dense, and nutrient-poor foods like cakes, chips, peanut butter and ice-cream.

‘Every fool can fast, but only the wise man knows how to break a fast’.

George Bernard Shaw

Sadly, some people who fast regularly end up getting less protein and fewer micronutrients than they need for optimal health and to prevent cravings and achieve satiety to manage their hunger. In time, they risk becoming ‘skinny fat’, where they have more body fat but less muscle than they started with, and worse metabolic health.

The reality is, there is nothing magical about fasting that eliminates your need for nutrients.  Your lizard brain will always work to ensure you get what your body needs, regardless of how much willpower you exert with your conscious mind.  You need to find a way to get enough restriction to achieve the benefits of fasting over the long term (e.g. weight loss, reduced blood sugar, increased insulin sensitivity) without pushing so hard that your Reptilian Brain steps in and undo all your hard work.

People who want to lose body fat need to find a way to get reacquainted with their true hunger signals. Rather than occasional herculean efforts, it’s more useful to make small incremental changes that empower you to retrain your lizard brain and true hunger signals and build sustainable habits. 

How your body uses fuel

To maximise resilience in any context, our bodies have adapted to store and use a wide range of fuels. The fuel we use to produce energy can come from the food we have just eaten or stored fat in our bodies. 

The table below shows the relative oxidative priority of alcohol, ketones, glucose and fat in your body (adapted from Oxidative Priority, Meal Frequency, and the Energy Economy of Food and Activity: Implications for Longevity, Obesity, and Cardiometabolic Disease by Cronise et al., 2017).  

 AlcoholKetonesExcess proteinGlucoseFatty acidsBody fat
UseEnergyEnergyEnergy & excretionEnergyEnergyStorage
Capacity (calories)20201200 – 200015040,000 – 500,000
Thermic effect15%3%20 – 35%5 – 15%3 – 15%3 – 15%

Some fuels are harder to convert into usable energy, and there are more losses in their conversion than others.  This phenomenon is referred to by several names, including the ‘thermic effect of food‘, ‘dietary-induced thermogenesis‘ or the ‘specific dynamic action of food‘. While these distinctions are typically ignored in our overly simplified discussion of ‘calories in’ vs ‘calories out’, they have a profound effect on the way our bodies use the food we eat as well as how much of it we tend to eat.

While we are always using a mixture of the available fuels to some degree, it makes sense that your body would want to use the fuels that it can’t store first.  The energy from alcohol and ketones must be used first because both these fuels are highly volatile.  We don’t have much room to store them other than in tiny amounts in our bloodstream.  Any energy available from alcohol (e.g. if you’ve just had a glass of wine) will be used first.  

Most of the time, ketones are only present when glucose and protein are very low.  If you have ketones in your blood (i.e. due to extended fasting, eating a lot of fat or exogenous ketones), your pancreas will secrete insulin to hold back the glucose in your liver and bloodstream.  

‘Excess protein’ is next in the oxidative priority ranking, so will be used after alcohol and ketones. However, it’s important to note here that most of the protein we eat is used for muscle protein synthesis and other critical bodily functions.  We typically do not consume ‘excess protein’ because it is extremely satiating, so we rarely eat more of it than our body requires.   

So, the remaining dominant fuel sources are carbs and fat.  While your body likes to maintain some glucose in your bloodstream, if you have too much, you won’t burn the fat in your blood.  

Counterintuitively, people who are carrying a lot of body fat are burning mostly glucose at rest.  When we measure their respiratory quotient (i.e. the ratio of CO2 exhaled vs the oxygen consumed) we find that they are actually working overtime trying to burn off the glucose that is ‘backed up’ in their system.   

Because you can only store about 5 g of glucose in your blood (about a teaspoon’s worth), a little dietary carbohydrate can quickly change your blood sugar levels (particularly if your fat stores are already full so you can’t easily absorb the excess energy).  

While we can convert sugar to fat (via de novo lipogenesis), most of the time it’s the fat in our diet that is stored because your body tries to burn off the glucose first.  Any leftover dietary fat can easily be stored.  

It’s not that fat is a better fuel source than carbs, but it’s the glucose that will show up in your bloodstream and register on your meter after you eat.  Glucose essentially ‘floats on top’ of the fat in your bloodstream and your adipose tissue.  

One of the widely underappreciated facts about fat loss is that you need to deplete the glucose in your bloodstream before your body can access your stored fat.

Some people talk about eating more fat to become ‘fat adapted’ so you can be ‘in ketosis’ and burn even more fat. But by understanding the oxidative priorities of different fuels you can see that to burn the fat on your body (rather than that ‘fat bomb’, ‘keto bar’ or ‘buttered coffee’), you need to find a way to deplete both the glucose and fat in your bloodstream first.

In your body, your fuel tanks are separate but interconnected.  As you deplete glucose in your blood, it will be refilled from the glycogen stores in your liver (note: glycogen is just the fancy name for the storage form of glucose).  Then, as liver glycogen starts to be depleted, your body will turn to the fat in your blood, and then finally, your body fat.   

You can think of your available fuels as though they are stacked up on top of each other (as shown below).  To burn body fat, you need to deplete the alcohol, ketones then both the glucose and fat in your bloodstream first.   

glucose in the blood
liver and muscle glycogen 
free fatty acids in your blood 
body fat

The image below shows how the glucose in our blood and the glycogen stored in our liver are related.  As we fast for longer, we use up the live glucose glycogen in our liver, and in time, our blood sugar reduces.  Rather than fasting for longer and longer, Data-Driven Fasting guides you to fast for just long enough to see your blood glucose drop, so you know you are making progress.  You can then give your body the nutrients it needs before coming back for another short burst of ‘fasting’.  Before long, as you drain your liver, your body will start to turn to your stored fat for fuel.  

Your Personal Fat Threshold 

As well as the differences between how the fuels are used, our bodies store each of these fuels in varying quantities.  

Although your body fat is your largest fuel tank, it can still become full and overflow.  For reasons we don’t fully understand yet (e.g. ethnicity, diet, inflammation, etc.), some people reach their Personal Fat Threshold at lower levels of body fat.  While most people develop Type 2 Diabetes after gaining a significant amount of excess weight, some people develop diabetes while still relatively lean.  

You may have heard the term ‘TOFI‘ (‘thin’ on the ‘outside’, ‘fat’ on the ‘inside’), which refers to the observation that some people carry their fat on the ‘outside’ in their adipose tissue under the skin (like the guy on the left). In contrast, others store excess fat ‘inside’ around their organs (like the guy on the right).

Your body fat acts like a sponge to mop up excess energy (because it is harmful to many bodily systems to have too much in your bloodstream for too long). Still, ultimately, just like a sponge can only hold so much water, there is a limit to how much energy your body fat can hold.

The amount of fat your body can hold comfortably on the ‘outside’ of your body (in your adipose tissue) is known as your ‘Personal Fat Threshold‘.  Once your body exceeds the amount of energy your body fat can store, your blood sugar levels start to rise as the energy ‘backs up’ in your system.  Excess energy overflows into your bloodstream (as high levels of glucose, ketone and free fatty acids) and is stored as fat around your organs.  Although storing fat on the outside of your body may not look great, it’s the fat on the inside that is more dangerous to your health.

Why blood sugar and insulin are so important

When someone exceeds their Personal Fat Threshold, they are at an increased risk of developing Type 2 Diabetes and other diseases related to energy toxicity or metabolic syndrome.   Maintaining healthy blood sugar and insulin levels is a big deal.  Elevated insulin and blood sugars are correlated with many modern diseases, including:

Unfortunately, there has been plenty of confusion and misunderstanding of the role of insulin in our bodies.  Optimising your blood sugars, insulin and body fat is not as simple as avoiding carbs and protein to prevent blood sugar spikes after meals.  

Insulin is a powerful hormone that is secreted by the pancreas. Its most well-known role is to facilitate the movement of glucose from the bloodstream into the cells of the body to be used – either as an energy source or to be converted to stored energy.  In healthy, non-diabetic individuals, insulin is secreted continuously by the pancreas during the day and night (i.e. basal insulin), with larger ‘pulses’ delivered when we eat (i.e. bolus insulin).

The graph below shows how different foods raise our insulin levels after eating. Notice how glucose (the black line) drives insulin up quickly, but after two hours, insulin levels return to baseline. In contrast, foods that contain a combination of fat and carbs (e.g. milk, the aqua/cyan line) have a smaller initial spike, but keep insulin levels elevated for longer, even beyond two hours.

The role of insulin that many people overlook, however, is that it also acts like a dam wall that holds back your energy in storage while you continue to eat (or digest what you have already eaten).

Unfortunately, there has been plenty of confusion and misunderstanding of the role of insulin in our bodies. Because the amount your blood sugar rises after meals is closely related to what you eat, lots of people focus on managing their blood sugar levels after meals as their end goal, believing that super stable, flat-line levels will lead to improved metabolic health and fat loss. 

Super stable blood sugars can be achieved by reducing carbohydrates and even protein.  Unfortunately, this often leads to a diet that is very high in fat when people simply swap carbohydrates for fat.  This often results in a nutrient-poor low satiety diet that leads to increased basal insulin levels and the total insulin produced by the pancreas across the day.   This, in turn, drives increased body fat and further increases in insulin levels across the day.

Optimising blood sugar, insulin and body fat is not as simple as avoiding carbs and protein to prevent blood sugar and insulin spikes after meals.

In a recent study (Hall et al., 2020), NIH researchers fed 20 participants a 75% fat or a 75% carbohydrate diet for two weeks. They tracked blood glucose continually and tested free fatty acids in their blood after meals.  The chart below shows how free fatty acids change after a low-fat meal (green line) vs a high-fat meal (red line).   We can see in the chart below that fat in the blood decreases more after a high-carb meal as the liver (controlled by insulin) slows the release of stored fat (through the process of ‘lipolysis‘) until all the energy that just came in from the food we just ate is used up.

The next chart, from the same study, shows that after eating a high-carb meal (green line below), blood sugar levels rose for about an hour and then fell back towards the baseline, but we see a much flatter response from a low-carb high-fat meal (red line below).

Unfortunately, reducing carbs and protein and increasing dietary fat only manages the symptom (by stabilising blood sugar after meals).  It will not necessarily help you lose body fat or reverse insulin resistance.  While some people believe that maintaining stable blood sugars and minimising the rise in glucose after they eat will help them lose fat, this is not necessarily the case.  

The chart below, from our analysis of people using Data-Driven Fasting, shows that there is no correlation between a smaller blood sugar rise and a healthier waist-to-height ratio.

What many people fail to recognise is that body fat (commonly assessed by the Body Mass Index or BMI), insulin and blood sugar are all highly, positively correlated.  

As shown in the chart below, the higher your body fat, the higher your fasting blood glucose is likely to be.

Similarly, the higher your BMI, the higher your insulin secretion levels are likely to be.

Hence, because fasting blood glucose level is closely correlated with the amount of body fat you are carrying, the only meaningful way to reduce your insulin and fasting blood sugar levels (and truly reverse Type 2 Diabetes) is to reduce the amount of body fat you are carrying.

How fasting works

When you haven’t eaten for a while, you will start to deplete the fuel available in the bloodstream. As these supplies are used up, your liver begins to release the glucose stored in your liver (i.e. as glycogen) to maintain stable blood sugars.

When glycogen stores are starting to become depleted, your body uses a process called ‘gluconeogenesis‘ to convert protein (and even fat) to produce even more glucose, which is used to refill your glycogen stores. This critical process ensures that you always have some stored glucose available for explosive activities when required.

It’s only when your glycogen stores are depleted (but not exhausted) that your blood sugar will start to drop, insulin decreases, and finally, you will begin to pull more energy from your stored body fat. Then, you’ll require less insulin to ‘hold’ fat in storage, and insulin levels over the day will decrease.  

Rather than modifying your diet to manage your rise in blood glucose and insulin only after meals, you need to reduce your average blood sugar and insulin levels across the whole day. While this may sound similar, the difference in the approach and results is radically different.

Whether you are eating high-fat or a high-carb diet, the key to burning stored body fat is to have blood sugar levels return to below your baseline before you eat again.

The secret to burning unwanted body fat

Wouldn’t it be great if there was a simple but precise fuel gauge for your body that you could use to tell if you: 

  • actually needed to eat (refuel) now, 
  • crave those yummy leftovers in the fridge because you know they’re there,
  • are reaching for food to soothe an emotional upset or relieve boredom, or 
  • think about eating out of habit (just because it’s ‘breakfast time’)?

A blood glucose meter is as close as it gets to having an instantaneous fuel gauge for your body to help you understand whether your hunger is real or you just want to eat any one of a multitude of reasons that are not related to your body’s healthy nutritional requirements.   

Most of the time, we focus on how much blood sugar rises after a meal. Maintaining blood sugar levels in the healthy non-diabetic range is important.  However, our analysis shows that:

  • most people who are interested in fasting, low carb or keto diets already have very stable blood sugars (with an average rise of 10 mg/dL or 0.6 mmol/L), and 
  • manipulating your diet to achieve even more stable blood sugars does not necessarily lead to fat loss or improved metabolic health.

The reality is, to lose body fat, you need to manage your blood sugar level before you eat.  In Data-Driven Fasting, you’ll learn how to use a glucose meter as a fuel gauge to lose fat without pushing your body too hard.  

Data-Driven Fasting uses your personalised blood sugar ‘trigger’.  When you feel hungry and think about eating, you simply test your blood sugar to validate your hunger to see if you need to refuel.  If your blood sugar is above your trigger, you can wait a little longer until your blood sugar has dropped below your trigger.  

Waiting until your blood sugar drops below your personalised blood sugar trigger point ensures your fasting routine is achieving a negative energy balance.  You will gain all the benefits of fasting (e.g. increased insulin sensitivity, improved blood sugar levels, weight loss, fat loss, and autophagy) over the long term without waking your inner lizard brain and triggering the binge-restrict cycle. 

Hunger Training

Data-Driven Fasting is designed to help you fine-tune your eating routine and find the minimum effective dose of fasting required to get the results you want. 

It is based on the knowledge that, to burn stored body fat, you need to deplete both the glucose and fat from your blood first.  To do this, we measure blood sugar levels and make sure that they drop below your personalised before you eat again.

Although there is nothing wrong with going 24 or 36 hours (i.e. skipping a whole day) without food, you need to be able to still make good food choices when you break your fast.  What you eat when you refeed is critical to ensure you get the nutrients you need over the longer term.  If you find yourself reaching for the ice-cream, cake or pizza after you have fasted, chances are you’ll do better if you are a little less ambitious next time.  

To make sure that the time you spend fasting does not awaken your Reptile Brain (and lead to poor food choices when refeeding), we make use of a concept known as ‘hunger training’.  

‘Hunger training’ simply uses your blood sugar as a fuel gauge. It is an exciting approach that has had some fantastic outcomes in recent studies. In the 2012 book called ‘The Glucometer’ Angela Ross recommended simply delaying eating if your blood sugar is above 5.0 mmol/L (90 mg/dL).  

Later, a 2016 study from the University of Otago in New Zealand (titled Adherence to hunger training using blood glucose monitoring), found hunger training to be extremely effective, with obese people losing 1.5 kg on average over just two weeks.  Importantly, they also found it was more effective for people to have a personalised trigger level rather than expecting them to reach what they considered to be an optimal blood sugar before eating.  

In the subsequent study in 2017 by the same group from the University of Otago (The Effect of Different Types of Monitoring Strategies on Weight Loss: A Randomized Controlled Trial), the researchers tested hunger training against

  • daily weighing, 
  • calorie tracking with MyFitnessPal, and 
  • counselling sessions.

Hunger training using a personalised blood sugar target was the only scenario where people lost weight, while everyone else gained weight

People did quite well when they simply tracked their weight, which made them more mindful of their eating. However, it was hunger training using pre-meal blood sugar that enabled participants to get in touch with their hunger signals and their actual need for food that led to the best outcome by far.

Conversely, calorie counting using MyFitnessPal saw the largest increase in weight out of the four approaches. It seems that people lose touch with their true hunger signals when they outsource their satiety to a smartphone app. Notably, the study also found that depression, anxiety and stress all worsened for participants who used MyFitnessPal.

Tracking blood glucose is empowering because it provides immediate feedback as to whether you really need to eat now.  Understanding your need for food based on your blood sugar gives you a greater sense of control.  When you see a high blood sugar, you can immediately think back to your last meal and understand how your unique metabolism responded. You quickly learn which meals keep your blood sugar higher for longer and learn to avoid them in the future.

Participants found they could accurately predict their blood sugar based on their hunger, particularly as their blood sugar started to decrease. Hunger Training enables us to retrain our understanding of our hunger based on our body’s actual need for fuel.

However, it’s important to note that hunger training had the poorest adherence.  This is not surprising given the imposition of testing blood sugar multiple times per day. Although incredibly useful, testing your blood sugar on a regular basis may not be viable for some people over the long term.  Some people love to track ALL the data, but most people thrive with the simplest system that will ensure long term success.  

Data-Driven Fasting

While this research is incredibly exciting, we realised that a number of improvements needed to be made to create a comprehensive and sustainable system for sustainable weight loss.

  • Firstly, choosing the right initial premeal blood glucose trigger is critical to the effectiveness of the Hunger Training Process.  In Data-Driven Fasting, we use the average of your blood glucose before you eat during Phase 1 – Baselining.  When you move into Phase 2 – Hunger Training, rather than meeting some arbitrary target, you only need to do a little better than your current average.  As you start to delay your meals a little, you will progressively drain your stored energy.  Before too long, you will find it easier to reach your initial trigger.  
  • To ensure you continue to make progress, Your Personised Trigger continually updates based on the average of the past seven days of tracking.  Continually updating your target based ensures that you continue to move forward, but not so fast that you wake your reptilian instincts and end up in a rebound binge.
  • While some people love ALL the data and want to know their blood sugar before and after every meal, most people don’t aren’t able to sustain this level of intensity.  To maximise the chance that you will maintain it long enough to get the result you want, you should only have to track just enough to ensure you are moving forward towards your goal.  During the first week of Data-Driven Fasting, you will learn a lot about how your blood sugars respond to the food you eat, but you will quickly transition to using the minimum effective dose of tracking to ensure you continue to move forward at a sustainable pace.

Data-Driven Fasting 30-Day Challenge

After trialling Data-Driven Fasting with more than six hundred people, we found that a structured approach was critical to ensure they avoided the common pitfalls and confusion. So we created the Data-Driven Fasting 30-Day Challenge to help people align your fasting schedule with their unique metabolism, goals, preferences and routine.

The Data-Driven Fasting 30-Day Challenge will guide you through the following critical elements to optimise your fasting routine.

  • Baselining – find your current personal trigger to identify true hunger and when you need to eat to refuel.
  • Current foods and meals – learn how the foods you currently eat affects your blood sugar. Which ones leave you satisfied? Which ones lead you to eat more than you need to?
  • Hunger training – learn to delay eating until your blood sugar is below your Personal Trigger to ensure you eat only when you need to refuel.  This will ensure you are lowering your blood sugar and insulin levels over the whole day and ensure you are burning your body fat.
  • Curb your late-night binging – use your waking blood sugar to identify if you are eating too late in the day.
  • Main Meal vs Discretionary Meals – identify the main meal that you will use to anchor your eating routine and ensure you get enough nutrients (e.g. family dinner).
  • Optimise your eating routine – Lock in your new eating routine that will guarantee you are moving towards your goals.

The challenge includes:

  • a 30-day Program to guide you to optimise your fasting routine to ensure you achieve your goals.
  • the Data-Driven Fasting Spreadsheet to track your progress and optimise your fasting routine.
  • the Data-Driven Fasting Manual that includes detailed instructions and answers to 91 frequently asked questions.
  • a Workbook that you can use to reflect on your learnings.
  • access to a Private Community on Facebook with daily posts and support.  
  • Weekly Live Q&A sessions where you can ask all your questions and get extra support.

Join here to get access to your Spreadsheet and all the other materials to make sure you’re ready for the next Data-Driven Fasting 30 Day Challenge.

Success Stories 

Data-Driven Fasting builds on some previous Optimising Nutrition articles that have continued to receive a LOT of traffic over the years.  We regularly hear from people who have made significant progress as they put these simple techniques into practice.  


Lori came across the How to Use Your Blood Sugar meter as a Fuel Gauge article in December 2018 and put it into action.  She simply waited until her glucose numbers indicated it was time to refuel.  Over nine months she trimmed off 30 lbs.  

As she focused on her blood sugars before meals, her weight came down.  She is now a massive advocate and has guided many others to success using Data-Driven Fasting.  Lori says: 

I am EVER so grateful for that article.  It gives me a way to know when my body needs fuel, and when I could wait.  

I have a chance to avoid what others in my family have suffered by having high blood sugar (often without even knowing).  Thank you!  I share that link all over the place!  

I have many friends that are also very grateful to know how they can peel off pounds that seemed persistent and accumulating despite YEARS of effort.

If not for finding your fuel gauge article, I would not be where I am now: at a healthy BMI and with hope for ageing with an excellent health span.  I am glad I can point people to your work.

Lori has been on some podcast recently where she described her journey.  If you’re interested, you can listen here and here.  We also recently had her on a Facebook Live chat that you can view here


Sue was the perfect beta tester for our Data-Driven Fasting system.  She had already lost a lot of weight after participating in a couple of our Nutritional Optimisation Masterclasses, but she was eager to lose a little bit more fat to achieve her ideal weight.  

After baselining, Sue started with an initial premeal trigger value of 5.1 mmol/L.   

She was diligent in tracking her glucose on waking and before each meal as well as her weight, body fat and waist.  

As she chased a lower blood sugar target, her weight and body fat followed.  Over 50 days, she lost a further 4.7 kg (or 9% of her body weight) at a rate of 1.15% per week weight loss with 2.6% per week fat loss!

With some attention to good nutrition using our Nutrient-Dense Recipes and some resistance training inspired by Ted Naiman, Sue was even able to gain lean mass!  

As you can see in this chart, Sue’s premeal glucose trigger is strongly correlated with her weight and body fat!   Rather than obsessing over her day to day weight fluctuations, all she had to do was wait until her blood glucose was below her trigger before she ate and everything else looked after itself! 

For more of her story, you can check the Facebook Live interview with Sue here.


Mark topped the weight loss leaderboard in our first Data-Driven Fasting 30-day Challenge with a massive 21 lbs (9.4% of his body weight) over four weeks.  Coming into the challenge, Mark was no stranger to the concept of fasting.  However, he was one of the many people that tended to regain weight after every fast that he did.  

However, after he started to follow the guidance given by his own body, the weight quickly began to fall off.  

He enjoyed learning the finer points of how his body used the fuels he was giving it and how he could measure the right things to continue to move toward his goals.  

Mark even started to feel a little smug as he saw the contrast between what he was learning and experiencing compared to the previous approaches he had followed.  

Mark had already lost a lot of weight but using his blood glucose as a fuel gauge seemed to be the secret to getting the rest of the weight off.

He also learned to prioritise nutrients and manage his fuel (fat and carbs) to ensure continued progress.  

As he chased a lower pre-meal trigger, weight, body fat and his waist followed.  

He also learned that managing his fat intake was a key part of reducing his blood sugar across the day.  

The cool part of the story is that both Mark and his wife Louise did it together, and they both achieved terrific results!   

Mark even learned to predict his blood sugar based on his hunger.  

For more of his story, you can check the Facebook Live interview with Mark here.


While most people try fasting to reverse diabetes or lose fat, Margaret’s goal was to gain health and energy as well as achieve a weight goal of 57 kg (125 lbs.).  

As she chased her pre-meal trigger down from 4.6 mmol/L to 4.0 mmol/L, she lost a phenomenal 8.1 kg (18 lbs.) or 12% of her body weight in just 33 days.  That’s 2.4% weight loss per week!   

Margaret is a singing teacher, conductor, wife and mother of two.  Despite some family celebrations and plenty of stressful days dealing with working out how to teach singing in lockdown, she was able to use DDF to get back on track.

But more than weight loss, we also encourage people following DDF to prioritise nutrient-dense high satiety meals when they eat, to maximise fat loss while preserving lean mass.  

Tracking changes in body fat is useful to ensure you are losing fat and not precious lean mass.  The “stacked” chart below shows Margaret’s lean mass and body fat changes.  We can see that during the four weeks, she lost 9.7 kg of body fat (21 lbs) and gained 3.2 kg of lean mass!

Spectacularly, she also lost 13 cm (5.2 inches) off her waist.

Margaret said, “I was amazed by how clear my skin and eyes are and how the dark circles under my eyes have all but disappeared!  Thank you so much, feel incredible. I have the most energy I’ve had in forever, and my skin is practically glowing. My favourite thing about it was getting back to eating with intention. DDF just made it all so easy. Congrats on developing such an awesome program. Excited to see this getting out there and helping people.”


Maureen wanted to do whatever it took to achieve optimal health.  

After making some progress as a DDF beta tester, she was eager to make some changes to get the results.  She was thrilled at her initial progress without feeling deprived.  

Unfortunately, knowledge and intelligence don’t always guarantee success.  Following a system that works consistently tends to yield the best results.  She surrendered to the process and got out of her own way, stopping her habit of overthinking things and was thrilled with her progress.  As she chased a lower pre-meal trigger value, her weight, body fat and waist measurement followed the downward trend.  

Over the 30 days, her trigger dropped from 97 to 83 mg/dL, she lost 7 lbs (which was all fat), and her waking glucose went from 94 to 83 mg/dL!  She was even brave enough to post some photos to share her progress! 

Maureen found that using her blood sugar as a fuel gauge helped her pay attention to her own body’s signals.  

In the end, she was all smiles and thrilled with the outcome.  Congratulations Maureen! 

For more of her story, you can check the Facebook Live interview with Maureen here.


At 62, Kathleen’s initial goal was to get below 25% body fat.  But after gaining 5 lbs of lean mass while losing 9 lbs of fat during the Data-Driven Fasting Challenge, she now has her eyes set on 23%!  

Over the first few days of the Data-Driven Fasting Challenge, Kathleen learned to take notice of her hunger and how her eating the previous day affected her blood sugars and appetite.  

She used her blood sugar as a guide to her eating routine to ensure she was achieving a negative energy balance

She got hooked on the data and as she saw consistent progress as she followed the process.   

Kathleen’s spreadsheet shows that chasing her pre-meal trigger down from 102 to 82 mg/dL, by optimising her meal frequency, ensured her weight and body fat followed a downward trend.

She found having a high-protein breakfast around her activity helped manage hunger.  

Even while losing weight, she was able to stay active.  Timing meals when you are most insulin sensitive earlier in the day seems to help a lot of people progress.  

After 30 days of consistent effort, she was thrilled with her results.  

Kathleen said:

I have been attempting to reduce the excess body fat I have for quite some time. I’ve been keto and then carnivore for a while to manage the autoimmune health issues I have. This way of eating has helped me feel better, but I was still dissatisfied as I wasn’t reducing.  

I decided to start as soon as I got the challenge materials and became hooked on doing my daily glucose readings. This way of intermittent fasting by using a glucometer and the level of hunger you’re experiencing is so easy! 

I love the fantastic tracking spreadsheet you get that’s colour coded to show where you need improvement and how well you’re doing. The daily lessons explain so much about glucose, and I had a lot of aha moments. 

The main lesson I learned is that my optimal time for eating is morning to midday. I had been eating midday to evening. Switched to breakfast and lunch most days and really saw progress. 

Not only did I have reductions in body fat, inches and weight, but I also gained muscle! And better yet, I’m sleeping and feeling a lot better, and I have energy like I haven’t had in a long, long time. DDF was exactly what I needed! 

I highly recommend DDF to anyone who is struggling to reduce weight and body fat.

For more of her story, you can check the Facebook Live interview with Kathleen here.


Congratulations to Linda who saw some incredible results in our recent Data-Driven Fasting 30-Day Challenge, with 

  • 22 lbs (10 kg) weight loss (i.e. 11% of her starting body weight) at an astounding rate of 2.7% per week,
  • 25 lbs of fat (11.3 kg) (26% of her starting fat), 
  • 3 lbs (1.3 kg) of lean mass gain, and 
  • 4 inches (10 cm) off her waist.

Linda’s tracking spreadsheet from the challenge shows the details of her amazing progress! 

As shown in the chart below, as her weight and fat mass dropped, Linda’s lean mass crept up!  Who said older people couldn’t build muscle?  Linda’s body obviously didn’t get that memo!

In addition to employing Data-Driven Fasting, Linda levelled up her game by focusing on getting adequate protein and maximising nutrient density, so she was still getting plenty of all of the vitamins and minerals to maximise her energy levels and prevent cravings. 

Linda’s said:

Placing first in fat loss, and weight isn’t just a win for me, but a victory for you, and all the other challengers who have played by the keto Low Carb High Fat rules for years, without achieving their goals.  All we ever needed was the right data.  

Your oxidative priority, PSMF, the Cleveland Clinic PSMF plan, and Protein Pulse Feeding for the Elderly, was my protocol.  

Sixteen years ago, at nearly 300 pounds, I got down to 195 pounds.  I’ve been HFLC since then, and have stabilised at about 200 pounds, and no matter what I tried, nothing budged.  

But you changed all that, and if it can work for a sedentary 73-year old, then there is hope for us all.  So the win belongs to us all.  

Your message is one of hope.  We can do anything if we have hope.  I am not diabetic, have no major health issues, and take no prescription meds.  And on DDF, I crossed from obese, to merely overweight.

Sorry to emote, but I just can’t believe the answer is already here.  Thanks again to you and Alex (and to your dear wife, for so freely sharing you with us).

Look at the smile!  It looks like it worked out OK for her!  Brimming with vibrant health!

What an inspirational story!  I love it.  Makes all the long hours creating these systems worth it!   Finally, Linda’s top tips for success:

  • Progress over perfection. 
  • Trust the process. 
  • Celebrate every victory, no matter how small.  
  • See mistakes as a learning opportunity, not a character flaw. 
  • Show up on the mat every day: Alex Zotov and Marty Kendall are fighting your corner. 
  • Lean on and learn from your DDF peers. There are none of us who cannot learn, and none of us who cannot teach. 
  • And finally, try to CHILLAX!

Phase 1 – Baselining    

Establish your baseline

In Phase 1 – Baselining, you will establish your typical blood sugars before meals where you typically feel hungry and choose to eat.  Establishing this personalised trigger is critical to ensure that Data-Driven Fasting is personalised to your metabolism and routine.  

If your Personalised Trigger is too high, you won’t stretch yourself or make progress.  However, if your trigger is set too low, you will have to fast for too long to reach it and may risk rebound bingeing, and you will be less likely to get the nutrient you require for satiety and to manage your cravings when you eat.  

Without changing what or when you eat, all you need to do is measure your blood sugar before your usual meals and snacks over three days.  We also recommend you test your waking blood sugar (after you get out of bed but before you eat anything and get on with your activities for the day) and your blood sugar one hour after your meals.  

After you have entered three days of baselining data into your spreadsheet, it will calculate, 

  • your typical waking blood sugar,
  • how much your blood sugars rise after meals, and
  • your typical blood sugar when you feel hungry and want to eat.   

Once you have finished the three of baselining, you will be able to reflect on your blood sugar values calculated by the tracking spreadsheet.  The spreadsheet is colour coded to highlight the highest readings (red and) the lowest (green).  You can think of green as good, and you are “go for eating”.

Waking blood sugar 

The average of your waking blood sugars for baselining is shown at the top of the first column (i.e. 4.9 mmol/L in the example below).  If your average waking blood sugar is higher than 100 mg/dL or 5.6 mmol/L, you are likely above your Personal Fat Threshold, you have some degree of insulin resistance (i.e. Pre Diabetes or Type 2 Diabetes) and you will benefit from losing some weight.  

Note: While your waking blood sugar is an important marker of metabolic health over the long term, counterintuitively, it doesn’t necessarily drop as you are losing weight.  Insulin resistance is a function of your insulin and your fasting blood sugars.  As delay your meals and eat less across the day, your insulin levels will drop, and your liver will dump more stored fuel into the bloodstream for you to use.  So some people see their waking blood sugars rise as their weight is in freefall.  So, you don’t need to worry if your waking blood sugars are all over the place during Phase 2 – Hunger Training.  As you chase a lower pre-meal trigger, everything else will fall into place.  If you find this confusing, then there is no need to test your waking blood sugars.

When do your blood sugars rise the most?  

The top row in the baselining spreadsheet shows the rise in your blood glucose rise after meals.  

Some rise in blood sugar after you eat is healthy and normal.  But reviewing your blood sugar rise after meals can help you understand if your current carbohydrate intake is a problem for you.  If your blood sugar rises by more than 30 mg/dL or 1.6 mmol/L after a particular meal, you probably should avoid that meal in the future (or at least eat less of it) to avoid overfilling your glucose stores.  

However, if your blood sugar rise after meals is less than 30 mg/dL or 1.6 mmol/L, then you don’t need to worry too much about reducing carbohydrates in your diet.  You can get on with focusing on your blood sugar before meals and maximising the nutrient density of the meals you eat.  Interestingly, the average blood sugar rise after meals during baselining for people doing Data-Driven Fasting is 10 mg/dL or 0.5 mmol/L.  This is well within the normal healthy range and indicates that most people who are interested in fasting are already following a low carb or keto diet and don’t need to focus any more or reducing their carbohydrate intake.  

It’s also useful to note when your blood sugars rise the most.  Due to reduced insulin sensitivity later in the day, most people find that their blood sugars rise more after dinner and the least in the morning when they are most insulin sensitive.  This is mainly because our energy stores are more depleted in the morning after an overnight fast and there is more capacity for them to be filled without backing up and overflowing into our bloodstream.  

Reflecting on when your blood glucose rises the most will give you a good indication of when you should be eating more or less.  If your blood sugars rise the most in the evening, then it may be worth trying moving more of your calories to earlier in the day.  However, if your blood sugars before your evening meal are the lowest, then you likely need the fuel then. 

While you don’t need to aim for perfectly flatline blood sugars, many people experience greater satiety once they reduce their intake of processed carbohydrates and their blood sugars stabilise.  

The baselining spreadsheet will calculate the average of your blood sugars before each meal (i.e. 5.0 mmol/L in the example below).  This will be your personalised trigger for the Phase 2 – Hunger Training.  

When are your pre-meal blood sugars lowest vs highest?

It’s also useful to review when your pre-meal blood sugars tend to the lowest vs highest.  If your premeal blood sugars tend to be highest in the morning and lowest before dinner, then you might want to consider moving more of your later in the day when your premeal blood sugars are lowest.  However, many people find their premeal blood glucose is highest in the evening, and their blood sugars rise the most after their evening meal.  

If your schedule allows it, there are many benefits in moving more of your calories earlier in the day when your body is primed to use the energy from your food rather than store it overnight and keep your metabolism working overtime while you are meant to be resting.  

Prioritising protein earlier in the day tends to promote greater satiety.  But your body has to work harder to metabolise the protein.  Due to the greater dietary-induced thermogenesis, you will produce more heat to keep you warm.  But it’s ideal if you’re not digesting your largest high protein meal at night.  Conversely, fat and carbs are easier to metabolise, so it can be smart to ‘top-up’ with a smaller meal with more fat and/or carbs later in the day.  

Over time, you will fine-tune your routing to your unique metabolism and routine.  

What foods raise your blood sugar the most?

You can also record your blood sugars before and after the meals that you eat in the ‘meals’ tab of your spreadsheet.  You can then sort this column based on the blood sugar rise after meals to identify the foods that cause the largest rise in blood sugar.   

Large swings in blood glucose can make us feel hungry.  If your blood sugars are falling quickly, we are more likely to feel compelled to eat.  Anyone injecting insulin knows how ravenously hungry they get when their blood sugars go too low.  They want to consume anything and everything to bring their blood sugar back up.  

Stabilising your blood sugar to normal healthy levels (i.e. a rise of less than 1.6 mmol/L or 30 mg/dL) is an important first step to gaining control of your appetite (but not the end game).  

Make a note of the foods that cause you to eat more of them or leave you hungry and more likely to be raiding the fridge later.  

  • Foods that are a combination of fat and carbs together with minimal protein send a signal to our body that it is autumn, and it’s time to get fat to prepare for winter.  
  • Conversely, foods with a higher percentage of their energy from protein and fibre (like we would find naturally in spring) tend to leave us more satisfied and less likely to overeat.  

During Phase 2 – Hunger Training, you won’t need to test your blood sugars after you eat.  However, if you’re still interested in how different foods and meals affect your blood sugars, you can continue to record them in the meals tab.  

Unless your blood sugar rise by more than 1.6 mmol/L or 30 mg/dL, we don’t recommend you cut back net carbs to below 15% of calories, as non-starchy veggies tend to be more satiating and nutritious than low carb high-fat foods.  

As shown in the chart below from our analysis of our series of 22 nutrient-dense recipe books tailored for different goals, optimal nutrient density tends to align with around 15% of energy from non-fibre carbohydrates.

Phase 2 – Hunger training

In Phase 2 – Hunger Training, you will start to use your glucose meter as a fuel gauge to help you determine whether you need to refuel or if you could wait a little longer and skip that snack or meal you were dreaming of.  

The goal here is not to avoid food for days at a time (i.e. multi-day fasting).  In Phase 2 – Hunger Training, you will simply wait for your blood sugars to drop below your current trigger value before you eat.  As you skip snacks and stretch the time between meals, your blood sugars will start to slowly drift down.  

There’s no need to be a hero.  If you push too hard, you will risk waking your reptilian brain and cause a binge response.  You just need to wait until your blood sugars are below your personalised trigger more often than not.  

While more compliance will be better, you only need to record a premeal blood sugar below Your Personalised Trigger more often than not to make progress.  There’s no need to rush this beyond what you are comfortable with.  Your trigger will drop fast enough to ensure you continue to move forward towards your goals.  Remember, it’s all about progress rather than perfection.  

There are many reasons we eat

We often eat mindlessly when we’re bored, for social reasons, for entertainment or because it’s “breakfast time”.   

The Japanese have a special word, kuchisabishii, which means to eat when you are not hungry, but your mouth is lonely.  Data-Driven Fasting is the perfect cure for kuchisabishii.  It simply gives you a simple, instantaneous measurement to validate your hunger to understand if you are eating out of habit or boredom.  

We have been thrilled with how effectively Data-Driven Fasting enables a wide variety of people with different goals precisely time their meals to ensure they actually eat when they require food and wait a little longer when they don’t.

If you’re trying to lose weight, reverse Type 2 Diabetes or improve your metabolic health, you should only eat:

  • when you are hungry, AND 
  • require energy based on your blood glucose.  

When you eat, for best results, it’s important that you prioritise foods and meals that contain more nutrients (i.e. protein, vitamins and minerals) per calorie (we call this nutrient density).    

In Phase 2 – Hunger Training, you don’t have to test on waking or after you eat (although you can if you want to).  Just check your blood sugars when you feel hungry and think of going to the fridge, cupboard or cafe.  

  • If your blood sugar is above Your Personalised Trigger, all you need to do is delay eating and allow your blood sugars to come down a little more.  
  • Wait half an hour to an hour before testing again.  Maybe try drinking some water or some other non-caloric beverage (e.g. black coffee or tea) while you wait.  The feeling of hunger may pass.  
  • Later, if you feel hungry AND your blood sugar is below your current trigger, then go ahead and eat.  
  • For example, if your trigger level is 5.6 mmol/L (100 mg/dL) and your blood sugar drops to 5.5 mmol/L (99 mg/dL) or below, then you’re good to eat a hearty meal if you’re hungry.  

Chasing the moving target – your personalised trigger

Before long, you should see your blood sugars drop more regularly below your trigger point.  The spreadsheet will calculate your new reduced trigger based on your average blood sugar before meals over the previous week.  

This ‘moving target’ is central to Data-Driven Fasting.  As you progress, you need to continually update your goals and move towards optimal.  Data-Driven Fasting is like progressive overload resistant training for your metabolism.  

You don’t go from couch potato to marathon runner overnight.  You work up to it progressively.  When you work out in the gym, you get progressively stronger and can lift heavier weights.  Data-Driven Fasting is like a workout for your metabolism.  You should take it slowly at first.  In the early days, the most important thing is that you show up and do something.  Before long, you will be able to lift heavier and heavier weights with ease, and more importantly, without pushing it so hard that you hit the wall and burn out.   

While it’s not that hard to be ‘good’ for a couple of days, you need to see how you go across the whole week.  Your new trigger won’t be updated until you have consistently logged an average pre-meal blood sugar below your initial trigger (established in Phase 1 – Baselining) for four days few days.  You won’t see an updated trigger value until Day 4 of Phase 2 – Hunger Training.   

Meal skipping vs delaying meals  

In the first few days of Phase 2 – Hunger Training, you will delay eating until your blood sugars drop below your personalised trigger.  Maybe you initially test at 8 am and find you have to wait until 10.30 am for your blood sugar to drop below your trigger.  This is great if you are working from home and can eat whenever you want, but perhaps not ideal in the long term.  

Over time, you can evolve your Data-Driven Fasting routine into more of a ‘meal skipping’ approach.  Although you may find you need to eat more on days you are active and fewer meals on others, you should start to see a regular pattern emerge in your tracking.   

Your meal skipping may look something like the following:

  • If you find your blood sugar is elevated before breakfast, skip breakfast and don’t test again until lunch.  
  • If you had a big breakfast and your blood sugar is still elevated at midday, skip lunch and don’t eat until dinner.
  • If you have a big breakfast and lunch, you may find that your blood sugars are elevated at dinner time, so you will skip dinner.  

Your body likes consistency.  If your eating routine is regular, your lizard brain will remain asleep, happy that it will get fed at a regular time each day.  But if mealtimes are random, your lizard brain may work to ensure you eat more at each meal just in case the next meal is delayed.   

Eating earlier is often better than later 

Many people find they binge uncontrollably at night, particularly if they have tried to restrict eating during the day.  Unfortunately, this can lead to poorer food choices, worsening waking blood sugars as well as overeating.  It’s amazing how much food we can put away when we are ravenously hungry and gravitate to the most energy-dense options available.  

Due to lower insulin sensitivity later in the day and larger meals at dinner, people often find their post-meal blood sugars rise more at night.  While eating more later at night may have been an effective way for our ancestors to maximise fat storage when we are most insulin resistant and could rest and store what we just ate, it’s probably not ideal for most people today.  

To help you find the right balance between delaying your first meal and stopping eating earlier, your spreadsheet will flag if your waking blood sugars are increasing.  If you find this is the case, you might want to try eating a protein-focused meal earlier in the day (regardless of your blood sugars).  This could be Your Main Meal.  You can then treat the other meals as Discretionary Meals based on your blood sugar when you feel hungry later.  

By testing your glucose level before you eat, you will find that you may skip “breakfast” and delay your first meal until later in the day.  Many people get a wave of hunger earlier in the day that they find they can push through until their blood sugars start to come down a little later.  To manage your waking glucose, you can also move your last meal forward.  As you do this, you play with shifting your first meal back and your last meal forward, you will find the optimal eating window that works for your unique routine and metabolism.  

Note: Eating a big meal later in the day is only one potential reason for elevated waking blood sugars.  Counterintuitively, some people find their waking blood sugar rises when their weight is in freefall.   Once they start eating less often, their insulin drops, and their liver starts dumping stored energy into the bloodstream to fuel your activity.  There is a practical limit to how much you can bring your last meal forward, so try not to stress about your waking blood sugars if you are not overeating at night or can’t optimise your routine any further  It’s likely that your waking blood sugars will stabilise later once you transition to maintenance at your goal weight.   

Want to play a guessing game?

A key part of Hunger Training is reflecting on your current sensations of perceived hunger and calibrating them with your actual need for food based on your current blood sugars.  

This is not easy to do, especially when you first start out.  However, we don’t want you to need to rely on testing your premeal blood glucose for the rest of your life.  Your glucose meter is only a crutch that you can use until you are able to acquaint yourself with your true hunger signals.

To make the Hunger Training process even more useful, we have added an option to guess your blood glucose before you test it.  Over time, the accuracy column in the spreadsheet will increase as you are getting better at estimating your blood sugars.  

This little ‘guessing game’ will gamify the fat loss process and make it fun and challenging.   Don’t be too disappointed if your accuracy is low at first.  Previous studies indicate that they have found that it is easier to guess your blood sugar more accurately when your blood sugars are lower before meals.   

Spreadsheet housekeeping

We have made the spreadsheet feature-packed to suit a range of different peoples’ preferences for tracking.  But all the columns can make it a little unwieldy and you probably sly won’t use them all.  You may not eat breakfast or snacks.  You may not want to record your eating window.  To tidy up your spreadsheet, you can simply right-click on the letter at the top of the column and select hide.  This will also make it easier to use on your phone.

The end game of hunger training

By taking small incremental steps forward, you will:

  • learn to differential hunger from habit (or eating because your mouth is lonely), 
  • learn to make better food choices (both in terms of quality and quantity) that don’t keep your blood sugars elevated for long periods, and 
  • progressively become more comfortable with lower blood sugars levels without becoming stressed and reaching for the most energy-dense foods.

Once you have learned these new skills through quantified mindful eating using Hunger Training, you will no longer need to rely on your blood sugar to eat like an adult and achieve your goals.    

When to move on from Phase 2 – Hunger Training 

There is no reason that you can’t continue with Phase 2 until you achieve your goal.  

You could keep driving your pre-meal target lower so long as you feel fine and still have weight to lose.   We have people with premeal trigger values as low as 3.1 mmol/L or 55 mg/dL who are continuing to lose weight as they chase a lower trigger.  

You will continue to lose weight as you progressively chase a lower pre-meal trigger value, especially if you focus on refuelling with nutrient-dense foods with a higher protein percentage than you usually eat when you are maintaining your weight.   

By refuelling only when they need to, many people have found hunger training to be extremely useful to help them lose body fat at a surprisingly rapid rate and reach their goal (in terms of weight, body fat, waist to height ratio, etc.).

However, in time, your blood sugars will start to stabilise.  You may get to the point where they don’t drop too much lower by delaying meals.  Someone who has healthy blood sugar levels will have less variability in their blood sugar, particularly if they follow a low carb or keto diet.  

As you progress towards optimal blood sugar control, the signal to noise ratio from your blood sugars will decrease, and hunger training may become less useful.  Factors like your emotions, hormones and activity may start to play a more significant role in the daily changes in your blood sugar compared to your food.  

If you find that testing through the day is too much hassle or your blood sugar is no longer varying significantly, we have a couple of other versions of Data-Driven Fasting that you may find useful.  

  • Phase 3.1 – Compress your eating window (using your fasting blood sugars) 
  • Phase 3.2 – Compress your eating window (using your weight) 
  • Phase 4.1 – Meal skipping (using fasting blood sugars) 
  • Phase 4.2 – Meal skipping (using your weight)

Each of these approaches is discussed below.  

Phase 3 – Compress your eating window

Most people graze all day, from the moment they wake up to the moment they go to sleep.  Limiting the number of eating opportunities is a great way to let your body have time to access your stored body fat and glucose.  

A 2015 study by Satchin Panda found that 10% of people who ate the least frequently ate 3.3 times per day while 10% of people ate more than ten times per day.  On average, participants met their energy needs for weight maintenance by 6:36 pm but kept on eating until bedtime at 11 or 12 pm regardless.  

They asked people to log each time they ate.  As shown in the ‘feedogram’ below, which shows the time when each participant ate, pretty much the only time we don’t eat is when we are sleeping.   

When participants moved their calorie intake earlier in the day and compressed their eating window from greater than 14 hours to less than 11 hours per day, they found many benefits including improved sleep, reduced body weight and more energy.

Compressing your eating window can be a great hack to avoid overeating.  If you identify yourself as someone who does not eat after 7 pm, you are less likely to find yourself alone with a packet of chips or a jar of peanut butter watching Netflix at midnight.

After dinner, your body goes to work digesting the food you ate, uses some of it, and tries to store the rest as glycogen (in your liver and muscle) and body fat stores.  The more you ate yesterday (particularly later in the evening), the higher your blood glucose is likely to be the following day.   

While it’s great to wait until your blood sugar drops below your trigger before you eat, you also need to keep an eye on your waking blood sugars.  If they are rising rather than falling, you may want to finish eating earlier.  

  • If your blood sugars in the morning are elevated, then bring forward your last meal or skip that late-night snack (e.g. stop eating at 8 pm rather than 9 pm).  Bringing your last meal earlier will allow your body to use up more of the energy in your bloodstream before you wake.  
  • You can also delay your first meal.   Many people find that in Phase 2 – Hunger Training, that they can ride out the perceived hunger earlier in the day, especially if their blood sugars are elevated, and wait a little longer.  If your fuel tank (based on your blood glucose level) is already full, you don’t need to fill up anymore, especially if you are not hungry.  

During Phase 3, we recommend you work to establish a regular routine that aligns with both your lifestyle and goals. Your circadian rhythm is set by not just sun exposure, but also your activity and eating pattern.  You also likely have a work and family routine that you need to align with.  

Several studies including this one have found that we experience “metabolic jet” lag and tend to put on weight when our mealtimes are erratic (e.g. eating later on Friday night and the weekend than we would during the week or if we skip eating for days at a time and then try to eat “normally” on other days).  

If you know you are going to have dinner most days with the family at 7 pm, you can treat that as Your Main Meal and structure your other meals around it.  Or perhaps you like a big cooked breakfast, but find it easy or convenient to skip lunch?  There are several fasting options you can use based on your preferences and routine.  

For optimal results, we find that people who prioritise the majority of their calories in the morning (i.e. early Time-Restricted Feeding or eTRF) and front load their protein tend to do better in terms of satiety.  

It’s not a showstopper if you can’t make your first meal your largest.  But if you find that you are overeating in the evening, shifting the bulk of your calorie intake to earlier in the day may help to reduce your overall daily intake.  

As shown in this chart from our analysis of half a million days of MyFitnessPal data, people who eat only breakfast and lunch tend to eat less across the day.  Avoiding overeating too late and prioritising the first meal of the day seems to be more optimal compared to grazing all day or even one meal a day.  

Once you skip dinner a few times, you’ll quickly find yourself hungry in the morning and fall into a new routine soon enough.

Each day record your waking blood glucose levels and the time of your first meal (black tea and coffee don’t count) and your last meal.  The spreadsheet will calculate your eating window and give you recommendations to try to compress your eating window a little more.  

There are two Data-Driven Fasting options to help you dial in your eating window.  

Phase 3.1 – Compress your eating window (fasting blood sugars) 

In this option, you will test your blood sugars each morning.  If your waking blood sugars are above your average, you will try to compress your eating window a little.  

Over time, your eating widow will tighten until you find a routine that allows you to continually reduce your waking blood sugars.  As you do this, your weight should also reduce, and your blood sugars during the day will stabilise.  

Phase 3.2 – Compress your eating window (weight) 

In this option, you simply weigh yourself each day (no blood sugar testing required!).  If your weight is above your target, you tighten your eating window until you find a routine that allows you to maintain your target rate of weight loss. 

You can choose a gentle rate of weight loss of 0.5%, which is more sustainable if you don’t have a lot of fat to lose.  However, if you are feeling ambitious, you can choose up to 2.0% weight loss per week 

In our Data-Driven Fasting 30-Day Challenges, we have seen an average rate of weight loss of 1.3% per week with a maximum of 2.7% per week (see Linda’s story here).  However, if you find you are not able to achieve this or are experiencing excessive hunger that leads to rebound bingeing on poor quality food, we recommend dialling back your target rate of weight loss.  

Phase 4 – Meal skipping 

Rather than thinking in terms of an eating window, it can be more useful to simply limit the number of times you eat each day.  In Phase 4, you can use either your daily weight or your waking blood sugar as a guide as to whether you should have one less meal than usual today.  

While it’s nice to have a tighter eating window to help you manage your food intake, limiting the number of times you eat a day will achieve the same result, potentially with less hunger.  Meal skipping is also a great way to manage your energy intake without tracking calories.  

Varying the number of times you eat each day can give you more time in a calorie deficit when insulin is low, and your fat stores are being used.  If your waking blood sugar is above your average or your weight is not dropping in line with your target, you can simply “turn off” one of these eating opportunities which will reduce your calorie intake for that day.

The charts below show how insulin and fat burning will change with different meal frequencies.  Again, keep in mind that if you find yourself gravitating to poorer food choices, you may want to experiment with smaller high-quality meals with a higher protein percentage and nutrient density.  

Phase 4.1 Meal skipping based on waking glucose 

This approach is ideal if your waking blood sugars are still above optimal levels.  In this version of Data-Driven Fasting, you will eat one fewer meals than usual if your waking blood sugar is above your current average.  For example, if you typically eat four times per day, you would eat only three times on days that your waking blood sugar is above your current average in the morning.  

Phase 4.2  Meal skipping based on your weight 

This version of Data-Driven Fasting uses your weight each morning as a guide as to whether you should skip a meal today.   

In your spreadsheet, you set a weight loss target and fat loss target.   If your weight is above your target in the morning, then skip a meal today.  It doesn’t matter too much if you are skipping breakfast, lunch, dinner or your after-dinner snack.   

Let’s say you have three meals and an after-dinner snack.  If your weight is above your target, you will simply skip a snack that day.  If your weight drops below your target the next day, then you can have your snack again, if not then you’ll skip it tomorrow too.  

This will force you to be more mindful and intentional as you plan what you will eat.  Over time, you may go from three meals and two snacks to three meals and then two meals with a smaller eating window.   

Phase 5 – Maintenance 

Congratulations! You’ve arrived at your goal weight!  From here, we recommend you continue to weigh yourself and take your waist measurements each week weekly.  If you find your weight or waist drifting back up, you can return to your preferred method until your weight comes back into line.  


  • Intermittent fasting is a useful way to manage our energy intake without tracking calories.  
  • By measuring the most useful parameters (e.g. blood sugars, weight, body fat and waist), you can ensure you are getting the minimum effective dose of restriction to ensure you move towards your goal (e.g. weight loss, fat loss, diabetes reversal, longevity, etc.).
  • Extended fasting can lead to dysregulated appetite signals and refeeding on energy-dense nutrient-poor foods.  Due to this, despite their restriction and deprivation, many people do not see progress over the long term.  
  • Hunger training uses our blood sugars to verify whether we need to refuel or not and whether our hunger is real.  By waiting to eat until our blood sugar is lower, we draw down our excess glucose and body fat stores.  
  • We can also use our blood sugars or our scale weight to refine our eating window as well as identify when we need to skip meals to ensure our weight loss continues at the desired rate. 

Frequently Asked Questions and Pro Tips

Since we started the Data-Driven Fasting Facebook Group to trial this system, we’ve received a LOT of questions as people try to make sense of their blood sugars.  A number of them come up again and again, so we’ve compiled some answers to frequently asked questions.   

1. What affect blood sugar levels?

As noted by Dr Jason Fung (author of The Complete Guide to Fasting) in the Optimising Nutrition group back in 2016 when we were developing Data-Driven Fasting, many things can affect your blood sugars, such as stress, exercise, illness or hormones.  

Tracking your blood sugars is a powerful way to ensure you give your body what it needs when it needs it.  However, there are a number of factors (other than what you are eating).  Many people find it confusing when they start testing their blood sugars for the first time.  It’s useful to be aware of these so you can get on with focusing on the simple signal given by your blood sugars before you eat and ignore the noise.  We hope these FAQs will help you be prepared ahead of time.

Don’t be too hard on yourself if you feel compelled to eat before your blood sugars drop below your trigger.   The intent of Data-Driven Fasting is to use your blood sugars as a guide.  You only have to log a blood glucose below your trigger more often than not to make progress.  There will be times when you chose to eat when your blood sugar is not below trigger.  When this happens, just observe the relationship between your hunger and your blood sugars, stress, mood, and hormones/time of the month for women and the other many other factors.  You will also get benefit in terms of improved blood sugar and weight loss if you can improve your stress, mood and sleep as well.   

If your blood sugar is above your trigger and you are hungry, and you chose to eat, you can try to eat a little less or prioritise nutrient-dense foods and meals with a higher protein percentage.  If your blood sugars are a little high, you know you still have plenty of fuel in your system and all you really need is nutrients.  This will allow your body to draw down on your body’s stored fat and glucose while providing the nutrients you need to function optimally and prevent cravings as well as preserve your precious lean muscle mass.  

2. Which blood sugar meter should I buy? 

If you don’t already have one, there are some nifty high tech and cost-effective blood sugar meter options available.   

A great option in terms of features and accuracy is Contour Next One, which has a smartphone app that helps you analyse your data.  It’s everything you’d hope a modern blood sugar meter would be!   

Rather than having the spreadsheet open all the time, you can make notes in the app and then transfer them to the spreadsheet on the weekend to calculate your updated trigger.  You can even add photos of your meals in the app.  

You can even program the app with Your Personalised Trigger so it will give a happy flashing green light when you are below your trigger.  You can get a nice little dopamine hit from the green light (rather than those less than optimal comfort foods).  

If you’re in the US and looking for a cheap meter, then the Walmart Relion is a good option.   But if you have the funds and find Data-Driven Fasting useful over the long term, it may be worth investing in a more accurate meter.  

It’s also important to note that there can be differences between meters (i.e. some read higher or lower than others), so it’s ideal to continue to use the same meter once you start to ensure you get reliable results.  

3.  Would a continuous glucose meter be better?

There are many continuous glucose meter (CGM) options available.  They are quickly becoming the coolest new biohacker toy to guide your dietary choices.

The Dexcom G6 is the gold standard for Type 1 Diabetes management and sends a reading to your phone or other devices every five minutes.  The Freestyle Libre is also awesome, and a little bit cheaper, but requires you to swipe the reader (or your phone across your sensor).  

However, a CGM may be excessive for what we are trying to achieve with Data-Driven Fasting.  If you’re looking to avoid the (little bit of) pain of testing, keep in mind that CGM sensors are not painless to insert and you will have to change them every week or so.  CGMs are also not cheap over the long term, especially if you don’t have insurance coverage!  

The goal of Data-Driven Fasting is simply to retrain your appetite by checking blood sugars when you feel hungry and before you eat.  If you can see your current blood sugar all the time, you’re more likely to eat because your blood sugar dropped below Your Personalised Trigger (even if you’re not hungry).  

Excessive focus on managing blood sugar rise after meals often leads people to low satiety high-fat foods that will slow their fat loss from their body.   We have found that most people using Data-Driven Fasting have a minimal rise in blood sugar after they eat (i.e. average of 0.5 mmol/L or 9 mg/dL).

As you can see from the charts below, more stable blood sugars do not align with a lower body weight or healthier waking blood sugars.  Unfortunately, focusing excessively on your blood glucose rise after meals can drive people to eat more low satiety nutrient-poor fat which often does not end in fat loss from the body.  While fat does not raise your blood sugar much in the short term, consuming excessive dietary fat will stop your blood sugars returning to below Your Personalised Trigger as quickly (see Want to lose fat? DON’T aim for stable blood sugars! (Why your CGM could be making you fat).  

Your liver will release glucose from storage into your bloodstream to keep your blood sugars stable.  Your blood sugars may even rise in anticipation of food.  Some people get confused when they check their CGM when they’re hungry, and later find that their blood glucose has risen by the time they have prepared their meal and are ready to eat.   

The goal of hunger training is simply to verify if your glucose has dropped below your trigger point when you are hungry, and hence you are starting to deplete your glucose and fat stores.  If you can see your blood sugars in real-time, you may be tempted to re-fuel just because your blood sugar drops below your target, even if you’re not hungry.  

So, a CGM is great if you already have one or you’re a cashed-up biohacker data geek, but it’s not necessarily going to be better for Data-Driven Fasting.  There are also benefits in the small hassle of doing the finger prick and recording your blood sugar before you eat.  After a couple of weeks, you will only need to check your blood sugars a couple of times a day.  This is much simpler and cheaper than wearing a CGM.  

We’d rather you avoid the confusion that seeing your blood sugar in real-time can create given you only need to use your blood sugar before meals to validate your hunger.  

4. How does exercise impact your blood sugar levels?

Taking a moderate paced walk or doing some low-intensity exercise can deplete your blood sugar.  Exercise at a lower intensity (i.e. where you can still breathe and talk easily) will tend to burn more fat as well as lower your glucose. 

Meanwhile, higher intensity exercise will cause a release of stored energy from your liver, and you may see your blood sugar rise.   Resistance training is useful to help build your metabolically active lean mass which will increase your overall metabolic rate.  

But be aware, if you do intense exercise, your body will release glucose into your bloodstream to fuel the activity.  This is not a problem, just something to be conscious of if you happen to test your blood sugars after exercise.  

People often don’t feel hungry after exercise because of this elevated blood sugar effect.  However, if you do feel hungry after your workout and your blood sugar is still artificially elevated due to the exercise, don’t be afraid to eat.  You may find that eating before or after your workout helps you avoid more intense hunger later in the day (which often leads to poorer food choices).    

If you do a heavy workout (e.g. high-intensity interval training, heavy squats or deadlifts that deplete glycogen stores) don’t be surprised if you find yourself hungrier later in the day as your body tries to refill your glucose and fat fuel tanks.  You can experiment with your meal timings to ensure you refuel before your blood sugar gets too low, and you end up in an all-out binge.  

It’s virtually impossible to accurately calculate the calories you burn during exercise.  It’s also easy to overeat due to increased hunger after your workout.  However, once the glucose surge has dissipated, your blood sugar will give you a good idea whether you are over or under-fuelling over the long term. 

Many people find it useful to have their protein-focused Main Meal around their workout and then use their blood sugar trigger for any other Discretionary Meals during the day once their blood sugars have settled down.

5. How does sleep affect your blood sugars?  

Getting good sleep is essential, especially when it comes to managing your cortisol and waking blood sugars.  Don’t underestimate the power of a good night’s sleep to stabilise your glucose and help you manage your appetite.  

We tend to sleep better if we’re not over full or too hungry.  Try not to eat a big meal just before you go to bed; otherwise, your metabolism will be elevated through the night.  

At the same time, you don’t want to be too hungry.  Your ketone levels rise after a long period without food to ensure you are energised to go out and hunt rather than lie down and have a deep sleep.  

6. Why would my glucose increase when I don’t eat?

It may seem counter-intuitive, but your blood glucose after meals or upon waking can increase as you start to lose weight, especially if you don’t have great metabolic health and/or have a lot of weight to lose.  

It’s as if your body has a lot of stored energy to unload and is eager to dump extra glucose and fat into your bloodstream.  While our goal is to reduce blood glucose, especially in the morning, as a sign of good overall metabolic health, keep in mind that when you are losing weight, your body is not in a steady state.  

If your other health markers (e.g. body fat, weight and waist) are moving in the right direction, then there is a good chance you will be in a much healthier position in the longer term once things stabilise.  

Rather than trying to fast for longer (which can cause your blood sugar and ketones to rise even more), it’s ideal to find a daily eating pattern that you can sustain.  Eventually, as you deplete your liver glycogen, and you should see your blood glucose levels come down as your body fat levels decrease.

7.  How should I adjust my diabetes medications when I start fasting?

Medications such as injected insulin will help to manage the symptoms of Type 2 Diabetes (i.e. elevated blood sugars), but do little to reverse the underlying cause (i.e. energy toxicity), and can make it harder to lose unwanted body fat.  

Injected insulin forces your body to hold fat in storage and can make you hungrier, which can lead to weight gain.  As you lose weight, you will see a reduced need for both injected basal and bolus insulin due to improved insulin sensitivity as you start to lose excess body fat.  

If you are taking any diabetes-related medications (especially injected insulin), you should pay particular attention to your blood sugars as you extend the time between meals and work with your health care team to adjust your medications to ensure that your blood sugars don’t go lower than you feel comfortable with (e.g. below 4.0 mmol/L or 72 mg/dL).  Not only will you feel unwell below this level, but you will also want to eat anything and everything until your blood sugar returns to normal.  

Finding a predictable routine is extremely important, and even more so if you are taking diabetes medications.  If you radically change your eating pattern (e.g. skipping a whole day of eating or multi-day fasts) your insulin needs will plummet, and you will risk hypoglycemia (i.e. low blood sugars).   

In Phase 2. Hunger Training, you will make incremental changes to your eating routine, which will allow you to slowly dial back your insulin.  While it’s ideal to maintain lower blood sugars, it may be prudent to progressively back off your insulin dosing and allow your average blood sugars to run a little bit higher until you develop a consistent routine and reduce the variability of your blood sugars.   As demonstrated in the CGM charts below, once your glucose variability reduces, you will be able to dial in your insulin dosing to maintain lower average blood sugars. 

8. How can I integrate fasting into my normal routine?

Try to fit your fasting schedule around your regular work and family routine.  If you typically eat dinner with the family, then you ideally wouldn’t skip that meal (even if it’s your only meal of the day).  Dinner could be Your Main Meal, and you can treat the other meals as Discretionary Meals using your blood sugars as a trigger for them (and not your family dinner).   

9.  Follow the trend, ignore the noise

You will quickly learn that your blood sugars can bounce around.  While this noise can be confusing, keep in mind, you are working to manage the long-term trends.  

The chart below shows an example of how blood sugars tend to decrease in our Nutritional Optimisation Masterclass.  While there is plenty of scatter from day to day, we see a trend over the longer term.

This next chart shows the weight of the same person for the same period.  As blood sugars decrease, weight also comes off.  Again, the data can bounce around from day to day, but there is a definite trend.  

While it’s useful to track body fat to ensure you’re losing fat and not too much precious lean muscle mass, you should be aware that body fat data can be even noisier.  But, as we chase a lower premeal trigger by delaying or skipping meals, in time, you will see weight and body fat trend down over time.

As much as you can, simply record the data and follow the recommendations without overthinking it.   That there will be some days when the data doesn’t go your way for no apparent reason.   

Feel free to use your brain to decide whether or not you need to eat even if your blood glucose is above your trigger.  While more compliance is better, you only need to wait until your blood sugar is below your trigger more often than not.

10. Hunger is not the enemy

With Data-Driven Fasting, your goal is to become more acquainted with your hunger, not ignore it.  You will grow to understand your hunger by giving it some attention until you understand it, and it will become your friend.  While extended fasting can lead to dysregulated hunger signals, Data-Driven Fasting will help you gain a better understanding of your true hunger.  

As your blood sugars stabilise, your body will become more comfortable with a small amount of hunger.  Soon, that little bit of hunger will no longer be uncomfortable.   You will ‘train’ your appetite and hunger as your lizard brain will become comfortable with a lower level of energy in your bloodstream.

11. The psychological impacts of data-driven fasting 

The goal of Data-Driven Fasting is to become more attuned to your hunger signals.   

While testing your blood sugar may sound like a hassle, a tiny amount of pain and inconvenience from the blood sugar tracking is not such a bad thing because it forces you to be more mindful and question whether you need to eat.  It interrupts habitual mindless eating and adds a quantitative check to see if you need to refuel.  

While many people find that calorie counting harms their mental health, Data-Driven Fasting puts you in control of your hunger and appetite with a precise fuel gauge.  

Like a roulette wheel or a slot machine, a little bit of measurement gamifies the intermittent fasting process as you wait for the green light on your blood glucose meter.  There is a little bit of luck (due to the many factors that affect weight and blood sugars) and a bit of skill involved (managing your eating routine and food choices).  But the prize is excellent metabolic health (not to mention looking and feeling great).  

12. Progress over perfection

Remember, your goal should always be progress, not perfection.   

Blood sugars can vary for a range of reasons.  You don’t have to be militant about not eating if your blood sugars aren’t dropping and you are starving hungry.  

If you have a bad day, that’s OK.  You will learn something, and you can always catch up.  The goal of Data-Driven Fasting is simply to be below your trigger point more often than not before you eat.  If your blood sugar is slightly above your trigger and you’re ravenously hungry, then don’t be afraid to eat.  It’s not absolute black/white, on/off or good/bad.  

Your glucometer is simply a tool to empower you with knowledge about whether you need to refuel, not to make you feel like a failure or wracked with guilt.  Hunger training using your blood glucose as a fuel gauge simply tells you if your hunger is real, and you need to refuel.  The process will be more sustainable if you don’t lose your mind trying to be perfect in the first few days and weeks.  

You should approach this as a curious student, eager to learn how your body responds to food.  Data-Driven Fasting will help you realise the impact of those “bad days”.  Before long, the “bad days” will become less frequent.  You will quickly learn that overeating and/or poor food choices will have a downside in the future, so you will learn to moderate your meals today. 

Feel free to stop if you feel you are becoming obsessive or it is consuming too much time or mental energy.  While some people love quantifying everything, others can quickly become overwhelmed.  We have designed Data-Driven Fasting to minimise the cognitive load as much as possible to maximise sustainability.  

If you feel ravenous, grumpy, light-headed and you can’t think straight, you have a report due or an important meeting, don’t be afraid to eat.  You can always catch up by skipping a meal tomorrow.

The goal is to gamify mindful eating using the most useful data we can get (i.e. your blood sugars).  Rather than relying on an external calorie counting app to tell you whether you are eating too much or too little, you are using your internal fuel gauge to tell you if you need to eat.  

As you start to skip snacks and delay meals, you will learn to become comfortable with a little bit of hunger and feel a lot more satisfied when you do eat.  

13. How do I stop snacking at night?

One possible scenario with Data-Driven Fasting is that you will eat a big dinner, check your blood sugar in the morning and find it is above your trigger, so you will delay eating until your blood sugars come down in the afternoon or before dinner.  But, later that evening, you find you are even more hungry at night and have less controlled eating and find yourself bingeing again.  This is particularly a concern if you see your waking blood sugars increasing.  

If you are reaching for energy-dense foods because you are too hungry after not eating all day, we recommend you try having a more substantial protein-focused meal earlier in the day, so you are less hungry at night.  

If you are finding that you are overeating because you are skipping meals earlier in the day, you might even want to reset Your Personalised Trigger a little higher so you can give yourself a little bit more leeway to eat earlier in the day.  Another option is to lock in an earlier meal that you will eat every day regardless and then use your blood sugar trigger to decide if you will eat the other meals.

Our data analysis suggests that we tend to eat fewer total calories if we spread our food out over two meals rather than one compressed eating window.   However, if you find that OMAD works for you, that’s fine, so long as you can get adequate nutrients in your compressed eating window (particularly protein).  You may find you alternate between one and two meals per day based on your trigger.  

If you find you are eating less than 1.5 meals per day on average, you should review the quality of the food you are eating.  We have seen many people with fairly low premeal triggers who are eating a very high fat “keto” style diet that enable them to consume a lot of calories in just a few meals.  

You can use our Free 7 Day Food Discovery Challenge to review your current diet and find some new foods and meals that align with your goals.  You should work to increase nutrient density and protein percentage by dialling back the foods that are currently adding the most dietary fat to allow your body to use your stored body fat.

14. Front-load your protein to hack your satiety

Our data analysis shows that people who eat more protein at their first meal of the day tend to eat a lot less across the day.  Do what you can to make sure your first meal is “hearty” with plenty of protein (e.g. steak and eggs, not a Bulletproof Coffee or croissant).  Perhaps you could eat a big breakfast and a small lunch or skip lunch at work and have dinner with the family if/when your blood sugars drop.  

Or maybe you have coffee first up (black or with just a dash of milk or cream) and eat a large cooked meal in the middle of the day and then a moderate dinner with the family after work.  

Data Driven Fasting is all about identifying the routine that suits you that allows you to move towards your goals.  Try to find a routine that works for you that allows you to eat in a controlled manner and avoid ravenous late-night hoovering of everything in the fridge.  

15. Three steps forward, one step back 

Don’t be surprised if you find yourself ‘backsliding’ occasionally.  

Weight loss is rarely a linear process.  It’s also natural to follow a fasting and feasting cycle that ebbs and flows with the varying needs of your body.  It’s normal and healthy to want to eat more at times, especially if you have been restricting for a while.  It may take a few days to get back to where you were, but it’s likely that you will be able to deplete your blood sugars more quickly than last time because you have been able to burn off some of your excess fat as well.  

If you find yourself really hungry, there is no need to be ashamed of eating to satiety.  However, as you follow the process, guided by your premeal trigger, you will iron out the kinks in your routine and ensure a long-term trend towards your goals.

16. Should I check my ketones when fasting?

As you fast for longer, your blood sugars will tend to decrease.  Your blood ketones (BHB) increase as your body starts to burn stored fat for fuel.  This chart shows my blood glucose and ketone values during a seven day fast.  You can see blood sugar slowly trends down over time while ketones rise.  

After not eating for days, ketones can get quite high.  However, in the first few days, they don’t rise that much.  But, you don’t need high ketone readings to be burning body fat.   

In fact, as your metabolic health improves, it’s likely that you will see your ketone levels decrease as the energy in your bloodstream decreases (i.e. from fat, glucose and ketones).  Once you reduce your body fat, any excess energy from your diet can easily be stored, rather than overflowing into your bloodstream.  

Ketosis is simply an alternative pathway to allow your body to produce an alternative to glucose to fuel your brain and vital organ when you don’t have enough oxaloacetate (from carbohydrates and protein) to allow protein to be burned in the Krebs cycle.  In our Nutritional Optimisation Masterclass, people tend to see their blood ketone values increase for a few weeks and then decrease as they begin to burn their body fat.  

Virta’s study results also showed that, after an initial period of elevated ketones in the first few weeks, over the long term blood ketones return to baseline as people lose weight and reverse their diabetes.  The ketone values were much lower than are typically believed to be ‘optimal ketone levels’.  When it comes to blood ketones, more is not necessarily better.  

Blood ketones are the storage form of ketones, while breath ketones (i.e. breath acetone or BrAce) is a more meaningful indicator of whether you are burning ketones (rather than forcing them to build up in your bloodstream).  So, if your goal is to understand if you are using ketones for energy (rather than storing them), tracking your breath acetone will be more useful than blood ketones.     

The bottom line is that testing blood ketones is not really necessary.  It doesn’t tell you much in addition to your blood sugars.  Ketone test strips can also be expensive, and the test results are hard to interpret.  So, unless you are just curious because everyone else is doing it and you have some excess cash to burn, save your money and skip the blood ketone testing.  

17. Why am I not losing weight?

If you are eating one or two meals a day and waiting until your blood sugars drop below your trigger point but still not losing weight, then it’s likely that you’re simply managing to load a LOT of calories into fewer meals.  

When fasting, what you eat is still critical!  In fact, food quality becomes even more critical when food quantity is reduced.  Don’t underestimate your reptilian instinct’s ability to outsmart your conscious brain to keep you alive, especially when you try to starve it.   

The good news is we can tame our lizard brain by reverse-engineering our diet to give your body what it needs, so your lizard brain stays asleep and doesn’t come in and make a mess of all our discipline and hard work. 

If you push your body too hard, your cravings for energy-dense foods will increase to enable you to get more energy in the compressed eating window.  Some people who eat a high fat keto diet with plenty of body fat to lose see their waking blood sugars remain elevated while their daytime blood sugars are low and stable.  This may be because you are filling up your fat fuel tank, so your body doesn’t need to draw down on stored body fat.

To understand if this is the case for you, it may be useful to track your food intake for a few days in Cronometer to check the macronutrient split of the food you are eating.  To also check the micronutrient content of your food and find out which foods and meals you should be eating to achieve a balanced diet at a micronutrient level, we recommend our free 7-day Nutrient Optimiser Tracking Challenge.

Our analysis of data from Optimisers shows that foods and meals that contain a higher percentage of protein are tough to overeat.  People who are getting closer to 40% protein experience greater satiety and effortless weight loss, whereas people who are getting closer to 15% protein struggle to lose their unwanted body fat.  Some people refer to this as ‘fuel pulling’ (where you pull glucose and fat from your body rather than your food), a Low Energy Diet or a Protein Sparing Modified Fast.

It’s easy to pack a lot of energy into your meals if they contain a lot of carbs and fat with less protein.  This is the basic formula for modern junk food.  Given the opportunity, your body will always choose the low protein energy-dense foods that allow you to consume more energy and store more fat for the coming winter.

Sadly, many people who fast choose to refuel on foods with a higher percentage of energy from fat, believing eating ‘fat to satiety‘ will lead to weight loss.  Unfortunately, our data analysis indicates that this approach just makes it easier to consume more energy.  If you want to use the fat on your body as fuel, eventually you need to manage the fat in your diet.  

Eating fewer meals and getting less protein is not ideal in terms of satiety or achieving optimal body composition.  Before focusing on nutrient density, in our Nutritional Optimisation Masterclass, we initially guide people to ensure they are getting adequate protein and then trim back the energy from carbs and fat to align with their goal.  

As shown in our analysis of our 22 recipe books, foods with a higher percentage of protein tend to have a higher nutrient density.  Focusing on nutrient-dense foods when you eat is incredibly important, particularly if you are trying to eat fewer meals.  

18.  What if blood sugar testing is getting too expensive or painful?

While using your blood sugars is the most powerful way to understand if you need to refuel, over time, you may find testing becomes expensive, too painful, or hard to do consistently.  If you find this is the case for you, there are several options.

  • Make sure you wait until you are actually hungry to test.  Over the first week or so you will get a feel for when your blood sugars are lower, testing will be less of a novelty, and you will tend to test less frequently.  If you’re only eating two or three times a day, you only need to be doing two or three tests.  
  • Rather than eating haphazardly based on your blood sugar, it’s ideal to have regular meal timings.  After a few days of Data-Driven Fasting, most people find they eliminate snacking and drop back to two or three meals a day with a regular schedule.  
  • In the Data Driven Fasting 30 Day Challenge and Program we guide people to lock in their Main Meal (that you eat regardless of your blood sugar) and then treat other meals as Discretionary Meals based on your blood sugars.  
  • If you typically have three or four meals per day and you find your blood sugar is elevated before you eat one of those meals, simply skip that meal and don’t test until the next normal meal. 
  • While your waking glucose is useful to help ensure that you are not eating too much too late, it can also be confusing when you’re your insulin levels drop and you are losing weight.  Feel free to skip the waking blood glucose testing.  You can always check again once you have reached your goal and are maintaining your weight.   
  • If testing two or three times during the day is still too much hassle, expense or pain then you can skip to Phase 3.1 (compressing your eating window if your waking blood sugars are above your average) or Phase 4.1 (have one less meal today if your waking blood sugar is above your average).
  • If you’re completely fed up with testing your blood sugars, you can use Phase 3.2 (which involves compressing your eating window if you are not meeting your weight loss target) or Phase 4.2 (have one less meal if you are not meeting your weight loss target).  

19.  Are there any added benefits from extended fasting?

While there may be benefits of extended fasting (e.g. no food for three or more days), there are also downsides.  Not many people enjoy not eating for days on end, and it can be hard to fit into a regular family routine.  

Even the fasting gurus admit that we don’t know what length of fasting is required to achieve benefit or the minimum effective dose and meaningful results.  Is it 24 hours?  36 hours?  Three days?  Seven days?  Or maybe fourteen days to get the full benefits of autophagy?  

Unfortunately, extended fasting does little to teach you to eat well when you do eat, and may lead to reduced diet quality, fat gain and muscle loss over the long term.  If you are not able to control our food quality when you refeed, you are trying to fast for too long and are unlikely to be making sustainable long-term improvements.  

The good news is that most of the benefits of extended fasting can be achieved by dialling in your daily meal routine (with nutrient-dense food when you do eat) to ensure a long-term energy deficit that leads to optimal body composition.   

Data-Driven Fasting will guide you to optimise your meal timing and enable you to focus on getting the nutrients you need with a sustainable routine over the long term.  

While there is plenty of talk about the benefits of fasting for autophagy, cancer and Alzheimer’s disease, there is very little data in humans to validate the theoretical benefits.  There is some research in autophagy in rodents.  However, mice aren’t tiny humans.  One day is equivalent to forty days for humans, so the equivalent of a 24 or 36 hour fast in a mouse would kill most people.  

What we do know is that all of these conditions are vastly improved by achieving and maintaining more optimal body composition.  As shown in the charts below, the relative risk of a range of cancers increases with increasing Body Mass Index (from Quantitative association between body mass index and the risk of cancer: A global Meta-analysis of prospective cohort studies: Obesity and cancer risk).   

The images below (from Waist-to-height Ratio Is More Predictive of Years of Life Lost Than Body Mass Index) show that our overall mortality risk increases with a higher BMI.

Many people wonder, “How many days should I fast for?”  What you really need to know is, “How can I optimise my normal eating to ensure that I am moving towards an ideal body composition and staying below my Personal Fat Threshold?”

20.  How do I know if I’m below my Personal Fat Threshold?  

While most of us focus on weight and body fat, being below your Personal Fat Threshold is arguably more important.  But how do you know if you are below your Personal Fat Threshold?  

As you can see from the chart below (from Association between fasting glucose and all-cause mortality), the lowest overall risk of dying from any cause aligns with a fasting glucose of less than 100 mg/dL (or 5.6 mmol/L).  

If your waking blood sugars are in the optimal range, it means:

  • you are insulin sensitive, 
  • your insulin levels are low, 
  • your body fat can absorb extra energy your food, and 
  • you do not have excess energy backing up into your bloodstream.  

Below 25% body fat for women and below 15% for men is excellent.  A waist to height ratio of less than 0.5 is ideal for both genders.  Pushing significantly below these levels may not be healthy or sustainable.  However, your fasting blood sugar is an even better indication of whether you are experiencing ‘energy toxicity’.  

21.  When should I test my blood glucose after eating?

Many people ask when they should measure their blood sugars after a meal.  For our purposes in the baselining period of Data-Driven Fasting is that it doesn’t matter, any time between 1 – 2 hours after you eat is fine.     

The rate your blood sugars rise and fall after a meal will depend on what you are eating and your unique metabolism.  As shown in the chart below, blood sugars rise quickly after a high carb low-fat meal (green line) while they will increase more slowly (and not as much) after a high-fat meal.  Testing one hour after you eat is a good rule of thumb, but you could do some extra testing (e.g. every half hour for two hours after a couple of meals) to find out when your glucose levels peak if you’re curious.  

You don’t need to worry about being too precise.  All we are trying to do in the baselining phase is: 

  • find which meals raise your blood sugar the most (and which ones you might need to avoid in the future),
  • identify when you are most insulin sensitive vs insulin resistant (e.g. if your blood sugars rise the most at night and less in the morning you might benefit from shifting your meals earlier), and 
  • understand if you need to worry about carbs raising your blood sugar or if you should just be focusing on more satiating nutrient-dense foods and meals.  

You don’t need to be too concerned unless a meal raises your blood sugars by more than 1.6 mmol/L or 30 mg/dL AND your blood sugars rise above the normal healthy range (i.e. 140 mg/dL or 7.8 mmol/L).  If this is the case for you, then you should consider eating less of that meal next time or not eat it at all.  

While higher fat foods will cause a smaller rise in blood glucose, you need to find the balance between getting adequate nutrition and stable blood sugars.  As shown in this chart from our analysis of our series of recipe books, very high-fat foods tend not to be as nutritious.   

While the blood sugar rollercoaster is bad, flatline blood sugars should not necessarily be your goal.  Stable blood glucose levels are a symptom of good metabolic health.  While we can achieve stable blood sugars with a low carb high-fat diet (i.e. manage the symptom), diabetes reversal and improved metabolic health require reduced body fat levels.  

When testing your blood sugar after meals, keep in mind that:

  • fast-acting carbs will raise your blood sugars quickly, but they may also come down quickly, 
  • high-fat meals will help you achieve more stable blood sugars, but they may stay elevated for longer before you are ‘allowed’ to eat again, 
  • meals that are a similar proportion of fat and carbs with low protein (e.g. cookies, croissant, milk chocolate, etc.) will fill both your fat and glucose stores and keep your blood sugars elevated for much longer, and 
  • nutritious foods and meals that contain a higher percentage of protein will give your body what it needs with less energy and allow your body to draw down on its fuel stores.

22.  How does that “time of the month” affect blood sugars for women? 

Females of reproductive age should be aware that cravings, blood sugar and insulin sensitivity will vary across the month.  Women with Type 1 Diabetes find that their insulin requirements increase by 10 to 15% in the days leading up to their period and then drop sharply while insulin tends to be lowest in the middle of the cycle around ovulation.  Other women find that their blood sugars are more elevated during their period.  

Cravings and water retention (along with associated water weight gain) also tend to increase.  So, if it’s ‘that time of the month’, you may need to be more gracious when it comes to waiting for your blood sugar to drop.  You may want to accept a slightly higher trigger value or default to your typical eating routine and just eat when you are hungry during this time.   

23.  What is a “good” trigger value? 

We find it interesting to see how we compare with everyone else to understand how far we have to go to catch up with others who are closer to optimal.  

The charts below show pre-meal trigger values during baselining vs waking glucose (in mmol/L and mg/dL).  As you manage your pre-meal trigger value, your waist, body fat and waking glucose levels will follow.  While the average trigger value during baselining is 100 mg/dL or 5.6 mmol/L, you can continue to delay your meals as you chase a trigger value down to 4.0 mmol/L or 76 mg/dL or even lower if you feel OK.  As shown in the charts below of premeal trigger versus waking blood glucose from people at the end of the Data-Driven Fasting 30 Day Challenge, some people can reach a trigger value as low as 3.1 mmol/L or 56 mg/dL 

24. Why does my blood sugar fall after I eat?

Some people find that their blood sugar drops after they eat.  This is not cause for concern, but rather a positive sign that you are metabolically healthy and/or you are not overeating carbohydrates.    

Because our glucose and fat stores in your liver are depleted after an overnight fast, many people see their blood sugars drop after their first meal because the energy they eat goes to replenish the stores in their liver rather than backing up into their bloodstream.   We sometimes refer to this as being more “insulin sensitive”, but this is simply because our energy stores are not overfull.  

When you eat a higher protein meal, your pancreas secretes insulin to enable you to use the amino acids to repair your muscles and organs, make neurotransmitters and a host of other functions.  Glucagon is also released by your pancreas to balance insulin, as shown in this chart (from Marks’ Basic Medical Biochemistry).  

For someone below their Personal Fat Threshold, this balance of insulin and glucagon means that blood sugars will remain stable.  Blood sugars may even decrease, which is an indication that you have plenty of capacity to absorb the meal you just ate and that the energy from your meal is not overflowing into your bloodstream.  

25. Why would my blood sugars rise after a low carb high protein meal?

Some people who are insulin resistant or have diabetes (i.e. insufficient insulin to maintain stable blood sugars) may see their blood sugars rise after a high protein meal as the glucagon kicks in to tell the liver to release stored glycogen.  Insulin is also released to keep blood sugars stable.  

However, if someone is insulin resistant, insulin does not work as effectively, and their blood sugars are not suppressed.  Therefore, people who are insulin-resistant may see a rise in blood sugars after a high protein meal because they have insufficient insulin to both metabolise the protein and suppress the release of glucagon from their liver at the same time.  

Some people see this rise in glucose and think they should avoid protein in an effort to maintain stable blood sugars.  However, this can just make things worse.  If you are insulin resistant (i.e. Type 2 Diabetes) or your pancreas is not producing enough insulin (e.g. Type 1 Diabetes) you are likely losing protein through gluconeogenesis and would benefit by focusing on a higher protein percentage to ensure that you don’t end up having to overeat to get the protein your body needs.

If you are insulin resistant because you are carrying excess body fat, then the solution is to focus on foods with a higher protein percentage to increase satiety and enable you to lose body fat without losing too much lean mass.  

If you are already lean (i.e. waist:height ratio less than 0.5) and you see elevated blood sugars after a low carb high protein meal then it may be useful to talk to your doctor to get your fasting insulin and/or c-peptide measured to understand if your pancreas is able to produce enough insulin to rule out Type 1 Diabetes or MODY.   

Rather than avoiding protein in an attempt to maintain flatline blood sugars, you should work to reduce the fat and carbs in your diet to enable your body to use up stored body fat while still providing adequate protein to preserve lean muscle mass.

For more detail on this, see Why does my blood sugar rise after a high protein meal? 

26. Don’t try too hard

Don’t try to push your blood sugar too far beyond your trigger point.  You want to feel a little hungry, not STARVING, before you eat.  Otherwise, you will be more likely to overeat at your next meal, and you will need to delay the following meal even further to bring your blood sugars back below your trigger.  

Data-Driven Fasting is a tool to ensure you are achieving an energy deficit over the long term.  Not surprisingly, it will become harder if you force a larger energy deficit as your lizard brain fights back to make sure you survive.

Your mission with Data-Driven Fasting is to find a sustainable rhythm that will allow you to move towards your goal (e.g. weight loss, fat loss, lowered blood sugar or improved insulin resistance) over the coming weeks and months.

Hunger training helps you fine-tune your eating schedule, retrain your appetite and hunger signs, and build long term habits.  If you push too hard, your body will find a way to compensate to avoid starvation.  Your goal is to find the minimum effective dose of fasting to move toward your goals in a sustainable manner.  Not only will this be easier to maintain, but it will also give you a better chance of success over the long term.

27. Quantified mindful eating

If you want to leverage the benefits of hunger training, you can make notes in the spreadsheet or keep a separate journal to record what you are learning and incorporate it into your routine in the future.  Unless you want to be testing your blood sugar before every meal for the rest of your life, it’s a good idea to build some new skills and habits to ensure this is sustainable for the long term.   

Before you eat, you want to be hungry, but not starving to the point that you binge.  When you eat, you want to be full and satisfied, but not completely stuffed.   You may want to save the image below as your wallpaper on your PC or the lock screen of your phone as a reminder.

When you feel hungry and think of eating, rate your hunger.  Take a moment to imagine what your blood sugar might be if you tested it based on your physical symptoms of hunger (e.g. grumbling tummy, weakness, light-headedness, etc.)?  

Before long, you will start to get a pretty good feel for this as well as understand the factors that can influence your blood sugars (e.g. exercise, stress, hormonal changes, etc.).  If you are hungry and your blood sugar is below your trigger, then go ahead and eat. There is no need to be a hero.  If you are not overly hungry, you are less likely to overeat and more likely to make better food choices.  

28. Plan what you will eat before you’re hungry

It’s important to plan what you will eat before you get hungry.  If you test and decide to delay your meal next meal, take a moment to imagine what you will have when you eat next.  Plan to eat nutrient-dense foods with plenty of protein to maximise satiety so you won’t have to wait too long to eat again.   You can also reflect on what you ate last that is keeping your blood sugar elevated.  

Your goal when eating should be to get adequate protein while keeping carbs low (to drain your blood glucose stores) as well as keeping fat low (to allow your body fat stores to be used).  When taken to the extreme, this approach is known as a Protein Sparing Modified Fast.  However,  any diet that works over the long term tends to have adequate protein with less easily accessible energy from fat and/or carbs.  Because you are not fasting for days at a time, you will be less likely to feel like you should congratulate yourself with a pizza or a doughnut because you feel you “deserve it”.  

29. What should you eat after fasting?  

What you eat is just as important as when, how much or how often you eat.  If you fill up on energy-dense nutrient-poor food, your body will be craving nutrients again sooner.  So when you eat, do whatever you can to maximise nutrient density to ensure you are getting the nutrients you need with fewer meals and less energy.

To help with this, we have developed a range of printable .pdf food lists to help you optimise your diet that you can access for free here.  If your blood sugars are still elevated, we recommend the blood sugar & fat loss food list.  If your blood sugars are relatively stable, then you can go straight for the fat loss food list.  We have also created a series of 22 recipe books optimised for a range of goals.  

The table below will help you find the right recipe book for you.  Click here or on the name of the book in the table to learn more. 

Approach Ideal for 
Low carb & blood sugarUse these if your blood sugars are consistently elevated (i.e. they rise more than 1.6 mmol/L or 30 mg/dL after meals).
Blood sugar and fat loss Ideal for anyone with elevated blood sugars and body fat to lose.
Fat loss Ideal for rapid fat loss with less hunger and cravings due to nutrient deficiencies and adequate protein to prevent muscle loss.
High protein:energy ratio Use this if you want to attack your body fat aggressively without losing muscle, with maximum satiety.  

30. Should I track my weight when fasting? 

You don’t need to track your weight every day during Phase 2 – Hunger Training.  

Due to changes in water and food in your gut, your body weight can jump around from day to day.  While knowledge is power, some people find that tracking their weight AND blood sugar at the same time will be a struggle mentally.  

Some people love all the data, and it helps to keep them accountable.  However, others find the data is too much effort to collect.  They may overthink the day to day fluctuations which can lead to burn out.   

While you can record your weight in the tracking spreadsheet every day, you only need to log your weight once per week to ensure you are making progress over time.

You should be pleasantly surprised that, especially in the first couple of weeks, you will lose weight quickly as your blood sugars decrease.  This may be mainly “water weight” (which is stored with the glucose in your liver and muscles).  However, once your glucose is depleted, your body will start to burn your stored body fat.  You need to go through this stage of depleting your glucose and losing water weight first before the fat loss journey can really start.   

31. How often should I track my waist?

We also recommend that you track your waist circumference each week.  As shown in the chart below, a waist to height ratio of less than 0.5 is an excellent indicator that your metabolic health is approaching optimal.  Your waist measurement doesn’t change quickly, so you only need to measure it once per week.  

Measure your waist just about your belly button at the narrowest point of your abdomen in line with your elbows.  The precise location and whether you tend to suck in your gut to let it all hang out don’t matter too much.  Given our goal is to track long term progress, all that matters is that you measure consistently.   

32. What are optimal body fat levels?

During Phase 2 – Hunger training, your pre-meal blood sugars will continue to decrease as you reduce your body fat levels to below your Personal Fat Threshold.  Using your blood sugar meter as a fuel gauge is an excellent indicator of whether you are carrying excess fat, regardless of your weight.  

A bodybuilder may have a high body mass index but still be healthy, so long as they are not carrying too much fat.  But even bodybuilders can gain too much fat in their pursuit of strength and will see their blood sugars start to rise.  Being strong doesn’t necessarily mean you have excellent body composition or metabolic health.  

Data-Driven Fasting is a great way to ensure that someone looking to gain strength doesn’t gain excessive body fat that will compromise their health.   As you reduce your body fat levels into the fitness and athlete levels of body fat, you will find that your blood sugars also start to decrease towards optimal.  

Essential fat10-13%2-5%

The pictures below show what this looks like visually.    

As well as losing body fat, it’s also important to do whatever you can to gain lean mass (i.e. muscle) through exercise, particularly resistance training.  It’s your lean mass that is metabolically active and “burns calories”.  

People who lose excessive amounts of lean mass during fasting often find it extremely hard to sustain their weight loss because their metabolic rate has slowed so much.  They have to maintain a VERY low-calorie intake to avoid rebound weight gain.  When you are extremely insulin sensitive, you can regain weight very quickly.  

As mentioned in this video from Dr Ted Naiman, morbid obesity and Type 2 Diabetes is the other end of the spectrum to being a lean muscular bodybuilder.  While it’s not necessarily healthy to have extremely low levels of body fat (and very hard to sustain) many of us need to work to move in that direction by losing body fat and gaining lean muscle mass.  

33. What are optimal blood sugar levels?

Generally accepted morning fasting and post-meal blood sugar ranges are shown in the table below.  

However, once your waking blood sugars are below 100 mg/dL or 5.6 mmol/L, you can rest assured you are working within your Personal Fat Threshold and minimising your risk of all the diseases associated with energy toxicity and metabolic syndrome.  

The majority of people who have used Data-Driven Fasting have excellent post-meal blood sugars (i.e. minimal rise after meals and are within the normal range) and hence don’t need to worry so much about limiting carbohydrates further.  

Once your blood sugar rise after meals is in the healthy non-diabetic range, the next logical step to manage your blood sugars across the day and waking blood sugars is to focus on reducing your blood sugars BEFORE meals by waiting until they decrease below your personal trigger.  

34. Will coffee “break my fast”?

Many people using Data-Driven Fasting enjoy a coffee or tea in the morning and delay their Main Meal until later when they are hungry and their blood sugar drops below their trigger.  

Your morning cuppa doesn’t need to count as a meal so long as you are not adding hundreds of calories worth of milk, butter, cream, sugar or MCT oil.  In Phase 2 – Hunger Training you wouldn’t need to bother testing your blood sugar before your morning coffee.  If you are tracking your fasting window (Phase 3), then you wouldn’t count your coffee or tea as your first meal.  

While there is plenty of debate over whether coffee or artificial sweeteners will break your fast and water only may be more optional, you need to find the balance between optimal and sustainable.  Many people will find themselves with headaches if they suddenly slash their caffeine intake, which will make it unsustainable.  

Most studies find that caffeine has a positive effect on metabolic rate and fat loss.  Bodybuilders often use caffeine as a ‘fat burner’.  However, if you’re not sleeping because you are drinking your coffee too late, you should stop earlier or cut back.  

If they test their blood sugars in the morning around their normal coffee, some people their blood sugar.  However, it’s hard to discern whether this is due to normal morning circadian rhythm effects (i.e. your body releases cortisol, adrenaline and stored glucose from your liver to boot you up for the day) rather than the coffee itself.  

If you really want to find out if your coffee is spiking your blood sugars, you could test your blood sugar before and after caffeinated and decaffeinated coffee.  However, given the goal of Data-Driven Fasting is to achieve a long term negative energy balance, the small raise in glucose around your coffee should not really be of concern so long as your coffee contains minimal energy, particularly if they enable you to compress your eating window in a sustainable manner.  

Rather than wondering ‘will this break my fast’, you should really be asking, ‘will this allow me to achieve a negative energy balance that will lead to fat loss and a lower waking blood sugar in the long term’.

35. How much protein do I need?

Protein requirements will depend on your lean mass and your activity level.  While 0.8 g/kg LBM is an absolute minimum to prevent deficiency, we tend to find people do better in terms of nutrient density and satiety with 1.8 g/kg LBM or ideally 2.2 g/kg LBM to prevent loss of muscle during weight loss. 

In percentage terms, we find people achieve better satiety and fat loss when they work up to 40 to 50% of their energy from protein.  However, rather than eating more high protein foods, this is achieved by getting adequate protein and dialling back easily accessible energy from both fat and carbs.  

While more bioavailable protein will help to preserve lean muscle when you are losing weight, if you find you are not hungry, you don’t need to worry so much about your absolute protein intake (in grams) so long as your protein percentage is higher than 40%. 

You can use our simple macro calculator to see how much protein you need and track your intake in Cronometer for a few days to see what you are getting from your current diet.   

36. Will fasting help my gut health?

While it can be hard to adjust to solid food after fasting for multiple days, many people find that intermittent fasting improves their digestion and gut health.  

As we eat more than we need more often, our gut struggles to keep up, and we get indigestion and overgrowth of particular bacteria.  As we eat less, we give our stomach a chance to rest and the excess ‘bad bacteria’ die off as they are not continually overfed with nutrient-poor inflammatory foods.  

37. How many meals per day should I eat?   

As you use your weight and blood sugar to monitor your progress, you should find that you quickly cut back on discretionary snacks.   

Our analysis of half a million days of food logging data found that people tend to eat fewer calories when they eat two meals per day.  We tend to choose more energy-dense foods when we’re REALLY hungry, so we often eat more with one meal a day than two meals a day.  It is also easier to meet your daily protein needs if you spread it across two meals rather than trying to get it all in at once.  

Many people who are older or less active find that alternating between one and two meals a day (based on their blood sugars) allows them to achieve long term success.  However, if you’re an active bodybuilder trying to build muscle, then more meals may be required.

Not surprisingly, if we eat more often, we tend to consume more calories.  You don’t have to jump to two meals a day immediately, but in time, you may settle on a manageable routine of two or three meals per day.  

If you find that two meals per day is still not working for you, you can decrease the size of those meals rather than skipping whole days of eating (unless you can ensure you can avoid eating highly energy-dense hyper-palatable foods after not eating for 36 hours). 

Data-Driven Fasting tends to work best when you use it to decide between one vs two or two vs three meals per day with a regular routine while focusing on food quality when you do eat.  

If you find you are not losing weight with less than 1.5 meals per day on average, we recommend you review your food quality and work to increase the satiety value of the food you are eating.  Nutrient-dense foods and meals will ensure you get the nutrients you need when you eat and will also help you to feel fuller with fewer calories and hence you will be less likely to overeat when you do eat.  

38.  How quickly will I lose weight with Data-Driven Fasting?  

The rate of weight loss with Data-Driven Fasting can be quite rapid.  Participants in the Data-Driven Fasting 30-Day Challenge lost an average of 5.1% of their body weight over six weeks.  The average weight loss was 4.1 kg (or 9.0 lbs) at a rate of 1.3% per week as people chased a lower pre-meal blood sugar value. 

More importantly, with a focus on nutrient-dense refeeding, participants in the Data-Driven Fasting 30-Day Challenge were able to lose an average of 14.4% of their body fat at a super impressive rate of 3.6% per week.  On average, participants who 3.9 kg of body fat (8.7 lbs). 

Greater compliance will lead to faster weight loss.  However, it’s critical to find a sustainable routine over the long term rather than pushing so hard that you find yourself bingeing due to excessive hunger which will derail your long-term progress.  Rather than pushing too hard, it’s much better to find a sustainable rhythm that allows you to maintain food quality when refeeding.

Keep in mind that, as your blood sugars decrease in the first week or so you will also lose a lot of water weight quickly (note: every gram of glycogen is stored with four grams of water).  After this initial loss of water weight, you will start to burn through your body fat, potentially at a slower pace.  Don’t be discouraged by the slower weight loss.  As you continue to chase a lower premeal trigger and the fat loss will follow.  

39. What is YOUR why?

Before you get too far into your Data-Driven Fasting journey, it’s important to reflect on your “why”.    

If you’re going to succeed at anything, you need to find the reason why you want to make a change.   Unless you have identified why you want to change, you probably won’t persist in taking the small incremental steps that will ensure your long-term success.  

Once you find Your Why, you can reflect on it and harness that motivation to keep you going through the hard times until you transform your hopes into habits!  

Some example whys include:

  • I want to lose weight.
  • I want to be healthy so I can enjoy my life to the fullest.
  • I want to reverse my diabetes.
  • I want to gain control of my eating habits.
  • I want to avoid the health conditions of my parents and grandparents.
  • I want to like what I see in the mirror.
  • I want to think more clearly.
  • I want to reduce my body fat without losing muscle.
  • I want to have more energy.
  • I want to be more physically attractive.
  • I want to be healthy.
  • I want to set a positive example for my kids.
  • I want to respect myself more.
  • I want others to respect me.
  • I want to avoid diabetes.
  • I want to be able to play with my grandkids.

40. What is your end goal?

It’s also valuable to think about where you would like to end up.  How long will you persist with Data-Driven Fasting?  What is your end goal?  For example:

  • I want to maintain a weight below X kg/lb.
  • I want to maintain a body fat of less than X%.
  • I want to maintain a fasting blood sugar less than X mg/dL or Y mmol/L.

Setting a concrete end goal will ensure you continue with the process for the coming weeks and months until you reach it.   We sometimes find that people continue with hunger training for too long to drive their body fat or premeal trigger below a realistic or sustainable point.  While this is a good problem to have, it is important that you transition to maintenance at some point and 

41. How long can I do this for?  

You can follow Data-Driven Fasting until you achieve your goal (e.g. a waist to height ratio of less than 0.5 or a body fat level of less than 15% for men and 25% for women).  

A premeal trigger of 4.5 mmol/L or 80 mg/dL tends to correspond with a waking glucose of around 4.9 mmol/L or 90 mg/dL which aligns with the lowest risk of all-cause mortality.  

Any form of dieting can get hard after weeks or months, so feel free to take a break and maintain your current weight for a while if life gets stressful.  You can always come back to it after a few days or weeks.  

Once you reach your goal, we recommend you transition to Phase 5 – Maintenance in your Data-Driven Fasting tracking spreadsheet where you will track your weight, blood sugar and waist each week.  

If you find you are starting to gain weight or your waking blood sugar is increasing, you can simply jump back into your preferred Data-Driven Fasting protocol and repeat the process until you arrive at your goal again. 

42.  Will Data-Driven Fasting help me lose weight if I don’t have diabetes?

Phase 2 – Hunger Training will work for most people who are trying to lose weight, even if they don’t meet the criteria for diabetes.  

While Type 2 Diabetes is diagnosed when you have a fasting glucose of greater than 7.0 mmol/L or 125 mg/dL, you can use Data-Driven Fasting to drive your premeal trigger down to quite low levels and your weight and body fat levels will follow.  

43.  What if my waking blood sugars are not dropping?

Your waking blood sugar is a key marker of metabolic health and an indication of whether you are holding excess in storage.  We have found that, during the baselining phase, lower premeal blood sugars are highly correlated with lower waking blood sugars.  

If you are achieving a negative energy balance, draining your excess glucose stores from your bloodstream and losing body fat, you should also see your waking blood glucose trending down over the long term.  However, there are a number of reasons that your waking glucose may not be dropping, even if you are doing everything else right.  

Scenario 1 – Eating too late 

We can push our last meal back so late using Hunger Training that we end up overly hungry late at night.  It should not be surprising that your waking blood sugars are still elevated in the morning if you are still digesting the meal from the night before.  

While many people find it easier to eat later in the day, you should work to personalise your fasting approach to suit your lifestyle and preferences.  However, you should be aware that many people find their blood sugars rise more later in the day.  In the second week of the Data-Driven Fasting Challenge, you will see if bringing your last meal forward a little helps to reduce your waking blood sugar.  

Plenty of studies (such as this one) show that people who eat more later in the day tend to have worse metabolic outcomes.  So, while it’s useful to make sure you wait until your blood sugars decrease to below baseline before eating, the best way to manage this may be to finish eating earlier and perhaps have a nutrient and protein-focused meal earlier in the day regardless of your blood sugars.  You can then treat your other meals as Discretionary Meals based on your blood sugar.  

Scenario 3 – Stress and poor sleep 

Poor stress and sleep will have an impact on your waking blood sugars.  High-stress levels can also lead to comfort eating.  Higher waking blood sugars can be an indication that you need to focus on managing your stress levels.  

Scenario 3 – Low protein percentage  

People who have body fat to lose but eat a lower protein percentage may see a minimal variation in their blood sugar during the day after meals.  However, their body is still able to release plenty of stored energy into their bloodstream overnight, which means their blood sugar is still elevated in the morning.  Prioritising a higher protein percentage (i.e. by reducing dietary fat and carbs) will provide greater satiety which will help with fat loss, and, in time, lower waking blood glucose.  

Scenario 3 – Your weight is in freefall! 

As you wait for your premeal blood glucose to drop below Your Personal Trigger, your insulin levels will plummet to allow your stored energy to flow into your bloodstream (i.e. as glucose, ketones and free fatty acids).  This is a good thing if you have fat to lose.  You are using up our stored energy and have plenty of fuel in the bloodstream even though you are eating less.  

So, if your waking blood sugar is higher than you might expect, but your premeal blood sugar, weight, waist and body fat are all heading in the right direction, you just need to be patient.  Insulin levels tend to drop, and ketones rise over the first couple of weeks of weight loss and often start to stabilise and find a new normal from there.  

If all your other markers are moving in the right direction, then you should expect to see lower waking glucose once your weight stabilises and your body has less energy to hold in storage.  If everything else is moving in the right direction, it might be prudent to stop testing your waking blood sugars and just focus on premeal blood sugars for now.

44.  What is Dawn Phenomenon? 

Your body clock (i.e. circadian rhythm) is closely tied to your eating, sleeping, activity and light exposure.  

As your body prepares to wake in the morning melatonin decreases and cortisol and adrenaline start to rise.  Your body releases more glucagon to dump glucose into your bloodstream to ensure you are fuelled and ready to bounce out of bed to start the day.  

This increase in glucose (stimulated by glucagon) is usually balanced by insulin which ensures your blood sugar is regulated and doesn’t rise too much.  However, people with diabetes or insulin resistance often find that their blood sugar increases a lot first thing in the morning due to what is known as the Dawn Phenomenon because the glucose release from your insulin is not balanced by adequate insulin to keep blood sugars stable.  

There is no need to eat immediately if your blood sugars are high, especially if you are not hungry.  Many people find they can push through the first wave of hunger in the morning, particularly if their blood sugars are elevated.  As you draw down on your excess fuel, you will start to see your waking blood glucose levels reduce.  

However, if you are finding that your waking blood sugar is not decreasing because you are waiting too long before your blood sugars drop below your trigger, it may be wise to have a higher protein meal earlier in the day when you start to feel hungry, even if your blood sugars are above your current trigger.  

The small amount of insulin from the protein-rich meal may help stabilise your blood sugars for the rest of the day as well as leave you less hungry and less prone to late-night binging that will cause your blood sugars to be higher in the morning.  

45. What is the best way to measure body fat?  

Tracking your body fat percentage is a useful way to ensure you are losing fat rather than precious lean muscle mass which is highly metabolically active.  The last thing you want to do is lose muscle and end up looking like a fat skeleton with a very low metabolic rate and have to maintain an extremely low-calorie intake to keep the weight off!  

There are many ways to measure body fat.  None of them are perfect.  

  • A DEXA scan is the most accurate but expensive and inconvenient, so most people are unlikely to do it regularly.  
  • The Navy Fat calculator is surprisingly accurate (i.e. aligns with DEXA scans) and is based on a simple measurement of your waist, hip and neck as well as your weight.  
  • The most convenient way tends to be bioimpedance which can be measured with most modern scales.  These may not be as accurate as DEXA, but they can give you a consistent trend to tell you if you are heading in the right direction over the long term (as shown in the example below from one of our 6 Week Nutritional Optimisation Masterclass participants).  

Bioimpedance scales count your water weight “lean mass” and hence it can bounce around from day to day and will also decrease initially as your blood sugars decrease and you lose ‘water weight’.   But over time, you should see a nice downward trend in your body fat levels.

If you look leaner and healthier, you probably are.  In the Nutritional Optimisation Masterclass, we use your body fat and lean mass measurements to dial in your protein intake.  However, body fat measurements are not critical for Data-Driven Fasting.  Your waist measurement and selfies will do the job just fine if you don’t have a bioimpedance scale.   

While we have seen several people manage to gain lean mass while losing fat mass, most people will also see a drop in their lean mass when they lose weight.  The best ways to protect against this are:

  • consuming adequate protein when you eat, 
  • resistance training to tell your body that it needs to keep your muscles, and 
  • good sleep and rest. 

46.  Electrolytes and fasting 

Electrolytes (i.e. sodium, potassium, magnesium, etc.) are critical, especially when you are losing weight.  

One of the many functions of insulin is to help your kidneys recycle electrolytes in your body.  When insulin levels decrease, you will lose excess water as well as more electrolytes.  You may feel light-headed or experience muscle cramps if you do not have adequate electrolytes on board.  Much of what we experience as “hunger” is a craving for minerals.  

While many people find adding mineral salt to their water, drinking bone broth or even pickle juice is helpful, it’s also critical to ensure you are getting all the essential minerals, not just sodium.   We have created an Optimised Electrolyte Mix with the optimal amounts and ratios of sodium, potassium and magnesium that you can try.  

The problem with mineral salts is that you can quickly reach your ‘gut tolerance’ so you still may not be able to get the amount you need from supplements.  As always, it’s best to get your nutrients (including minerals) from food first and supplement only if necessary.  

To find out whether you need more minerals in your typical diet (and which foods and meals you need more of), you can track your usual food intake using our Free 7 Day Food Discovery Challenge

47.  How can I optimise my sleep with intermittent fasting?

Not eating too late in the day also seems to help us sleep better.  According to Professor Matthew Walker in his book Why We Sleep, we don’t enter REM sleep while we are burning off a lot of energy from a late dinner.  This survey of Oura Ring users shows that not eating too late is by far the most beneficial “hack” to ensure good sleep based on their quantitative data.  

Don’t be surprised if you find you sleep more soundly as your blood sugars start to decrease because your body is not working so hard to process excess energy overnight.  But at the same time, it’s good not to be too hungry when you go to bed.  If you find you are waking up through the night because you are hungry, then you may need to eat something a bit closer to bedtime. 

48.  Do I have to check my blood sugars before every meal?

No.  You don’t have to check your blood sugar before every meal of the day.  In time, you should identify one Main Meal that you know you eat well at a regular time each day (e.g. dinner with your family or your protein-packed breakfast) and use your blood sugar to decide whether you eat at other times through the day (i.e. Discretionary Meals).   

49. Eat “breakfast” like a king 

While you don’t have to have ‘breakfast’ first thing in the morning, it appears to be ideal, if possible, to front-load your calories towards your first meal of the day rather than eating your biggest meal right before you go to bed.   This is known as early time-restricted feeding (eTRF).  

Not only are you more insulin sensitive earlier in the day, but you are also more likely to use the food you just ate to fuel your activity rather than storing it while you sleep.  If your schedule allows it, you should try to eat most of your food when the sun is up to synchronise your circadian rhythm with your eating patterns.  

If you are finding you are overeating at night and your waking blood sugars are not coming down, it might be worth locking in a protein-focused Main Meal earlier in the day (even if your blood sugars are still above your trigger point) so you are less hungry and hence less likely to binge at night. 

50.  How much should my blood sugars rise after a meal?  

Data-Driven Fasting focuses on your blood sugar before meals to ensure you are reducing your body fat.  As your insulin sensitivity improves, your waking blood sugars and post-meal blood sugars should also start to fall in time.  

Be careful not to try to achieve flatline blood sugars by avoiding protein and all carbs (especially non-starchy vegetables which can be nutritious and satiating).  However, if you see your blood sugar rise by more than 1.6 mmol/L or 30 mg/dL in the one to two hours after you eat, it means that you likely ate too much or too many carbohydrates at that meal.  

Many people find that their blood sugars rise more after dinner, which is an indication that their energy stores are being overfilled and they may benefit by reducing the size of their dinner and prioritise larger meals earlier in the day.  

So long as your blood glucose is staying within the ‘normal range’, a larger rise in glucose after you eat is more a reflection of what you ate (i.e. too much fast-acting carbs), while your fasting blood sugars and your glucose before meals is an indication of your metabolic health and whether you are over-fuelling across the day.  

During Phase 1 – Baselining, you will get an idea of how your blood sugars respond to your current diet and whether you need to be concerned about reducing your carbohydrate intake.  

It’s not that we are promoting more carbs, but have found that most people won’t need to be too concerned about their post-meal blood sugar if they are focusing on nutrient-dense whole foods which typically don’t contain refined grains or added sugars.  

Of the more than six hundred people that have completed the baselining stage of Data-Driven Fasting, the average rise after meals is 0.56 mmol/L or 10 mg/dL (i.e. well within the healthy non-diabetic range).  Hence, it appears that the vast majority of people would be best served by managing their pre-meal blood sugars by delaying meals rather than trying to control the amount their blood sugars rise.

51.  Can I edit my spreadsheet on my phone?

The Data-Driven Fasting spreadsheet works best on a PC browser.  However, you can save it to OneDrive and use the Excel app on your phone.  Alternative, you can save it to Google Drive and edit it using the Google Sheets app.   

52.  How is Data-Driven Fasting different from calorie counting?

Managing calories in vs calories out sounds simple, but it is incredibly difficult to implement over the long term.  The reality is that all calories count, but only if you can accurately count ALL the calories (which we can’t).

Tracking is inaccurate, our energy needs change over time, and our lizard brain often finds a way to trick us into eating more.  Our subconscious survival instincts also don’t like to be controlled by an external force for too long, and psychological disorders can develop.  

Data-Driven Fasting respects the law of conservation of energy but uses your blood sugar or your body weight as a fuel gauge to guide your meal timing to ensure that you are in a negative energy balance and moving towards your goals.  This excellent video from Optimsing Nutrition advisor Dr Ted Naiman gives a great overview of the challenges with tracking calories to lose weight.  

53.  How is Data-Driven Fasting different from other popular approaches? 

Most approaches to fasting encourage you to not eat for days at a time in the hope of reducing insulin and driving autophagy.  By contrast, Data-Driven Fasting focuses on the long term trend with shorter bursts of restriction to ensure your blood sugars and weight are moving in the right direction.  

Just like any smart fitness training routine balances exercise and recovery to ensure positive adaptation, Data-Driven Fasting ensures that your short periods of energy deficit are balanced with nutrient-dense feeding to achieve long term progress.

By doing this, we ensure that diet quality is maximised (i.e. adequate protein and nutrients) during feeding rather than the energy-dense bingeing that often follows multi-day fasts.  By achieving a balance of adequate duration of fasting and quality feeding, we optimise the long-term trend to move towards our goals.  

54.  Will ‘too much protein’ raise my insulin levels and stop me losing fat?  

Refined carbohydrates raise insulin more over the short term, protein raises insulin over the medium term, while fat raises insulin over the longer term.  

However, while we typically focus on the change in insulin levels due to our food, our overall insulin production across the day is more closely related to our total calorie intake and our body fat levels.  

We require insulin to keep our body fat in storage while we eat.  Insulin regulates the release of stored energy from storage via our liver while we have energy coming in from our mouth.  Someone with Type 1 Diabetes will essentially disintegrate, with all their stored energy flowing into their bloodstream, if they do not inject enough insulin.  However, for someone who has a functioning pancreas, the insulin produced by their pancreas will be proportional to their body fat levels and how much energy they need to keep in storage.  

While protein does elicit a short-term insulin response, it is the also most satiating macronutrient.  Prioritising adequate protein when we eat allows us to eat less over the long term, reduce body fat levels and hence require less insulin across the day.  Again, satiety is about getting a higher percentage of protein rather than necessarily consuming more protein.  This is achieved by progressively dialling back the energy in your diet from fat and carbs.  

55.  Do I need to worry about insulin?  

Many people focus on insulin as the “root problem” and lowering insulin as the end goal.  However, if you are part of the 99.99% of the population that has a functioning pancreas, your body won’t produce more insulin than you need to keep your body fat in storage while food is coming in from your mouth.  

When someone with Type 1 Diabetes injects excess insulin, their liver will reduce the release of energy into your bloodstream, and their blood sugars will drop.  They will feel ravenously hungry and will eat anything and everything until your blood sugars rise again.  

However, unless you are injecting insulin (i.e. Type 1 or insulin-dependent Type 2 Diabetes), high insulin levels do not cause overeating or obesity.  The reverse is true.  High insulin levels are caused by overeating and obesity.  Rather than worrying about ‘insulin toxicity’, should focus on managing energy toxicity and insulin will look after itself.  

The Carbohydrate – Insulin Hypothesis simplistically assumes:

carbs -> insulin ->  fat storage 

But in reality, it is a little bit more complex. It’s critical to understand the true cause and effect relationship.  Rather than addressing the symptom, we need to focus our effort and attention on addressing the root cause.  A rise in insulin is simply the response to increased body fat (not the cause).  That is:

low satiety nutrient-poor foods -> increased cravings and appetite -> increased energy intake -> fat storage -> increased insulin

Hence, the solution to managing your diabetes, blood sugar, insulin levels and avoiding the complications of metabolic syndrome is:

high satiety nutrient-dense foods and meals -> decreased cravings and appetite -> decreased energy intake -> fat loss -> lower insulin levels

By managing blood sugar, you will reduce your body fat which will, in turn, reduce your insulin levels.  Sadly, focusing too much on maintaining flatline blood sugar and insulin levels can lead us to consume energy-dense high fat low satiety foods that lead to weight gain and increasing insulin resistance over the long term.  This is why, with Data-Driven Fasting, we encourage you to keep it as simple as possible and just focus on your blood sugars before meals.   

56.  Will I be getting enough autophagy with Data-Driven Fasting?  

While there is a lot of talk about autophagy (i.e. self-eating) when we don’t eat, there is very little understanding of the actual length of fasting required to achieve an optimal amount of autophagy.  

Even the smartest fasting gurus admit that we don’t know what length of fasting is required to achieve benefits or the minimum effective dose of fasting to achieve meaningful results.  Do you need 24 hours, 36 hours, 3 days, 7 days or maybe 14 days to get the full benefits of autophagy?  

Unfortunately, studies done on yeast and worms in a Petri dish aren’t really relevant to humans living in the real world who also need to be robust and resilient to survive into old age.  Valter Longo has shown that cycles of 48-hour fasting produce benefits in mice.   But mice aren’t tiny humans.  One day for a mouse is equivalent to 40 human days.  So the equivalent of a 48 hour fast in a mouse (i.e. 80 days) could kill many humans.  

While people often refer to Angus Barbieri who fasted for 382 days and came out thin and healthy, they don’t talk about the ten young men in their 20s that died after not eating for between 46 and 71 days in the 1981 Irish Hunger Strike

Autophagy is occurring to some extent all the time, particularly when we are not overfed.  Too much autophagy can be harmful if you are losing precious lean muscle mass when you fast and don’t get enough protein when you eat.  

What we do know is that achieving a more optimal body composition, body fat, fasting blood sugars and waist to height are highly correlated with reduced risk of dying of any cause.  

Too much autophagy can actually be harmful if you are losing precious lean muscle mass when you fast and don’t get enough protein when you eat.  Data-driven fasting ensures you get regular small episodes of autophagy as your critical markers (i.e. body fat, blood sugars, insulin, etc.) move towards optimal.  

These cumulative smaller bursts of autophagy followed by nutrient dense refeeding are much more likely to be beneficial than occasional multi-day fasts followed by energy-dense nutrient-poor binging.  

57.  How is Data-Driven Fasting different from the Fast Mimicking Diet?  

The Fast Mimicking Diet attempts to provide a small amount of nutrients and reduced protein during a multi-day fast.  Developed by Valter Longo, the FMD stems from a plant-based belief system where animal protein is bad.  Data-Driven Fasting is more like a Protein Sparing Modified Fast, which prioritises adequate bioavailable protein and more nutrients per calorie during the limited feeding opportunities.  

By maximising nutrient density, you will ensure that your body gets what it needs during weight loss to optimise mitochondrial function, prevent loss of metabolically active lean muscle mass and minimise cravings. 

58.  Do you need MCT oil or butter during a fast (aka “Fat Fasting”)?

Adding refined oils or fats will be counterproductive if your goal is fat loss, insulin sensitivity, improved body composition, nutrient density or diabetes reversal.  

59.  Should I exercise?

Resistance training is critical to send a signal to tell your body that you need to maintain your muscle during weight loss.  But be aware that your blood sugars may go up or down when you exercise, so you should only use your blood glucose as an indicator of when you should eat after your blood glucose has settled down (i.e. an hour or two after exercise).  

If you feel hungry around your workout, you could choose to eat your Main Meal in the morning just before or after your workout (regardless of blood sugars).  Ideally, this should be protein-rich to support recovery.  You can then treat the other meals and snacks across the day as Discretionary Meals and only eat if your blood glucose is below your trigger.  

60.  Can I fast when I’m stressed?

The extra adrenaline and cortisol from stress can cause your blood glucose to rise, regardless of what you eat (or don’t eat).  Stress can also cause your lizard brain to become troubled, so you will comfort eat to prepare for an emergency (e.g. famine or to run away from a predator).  

As well as waiting to eat, you can lower your blood glucose by doing whatever works for you to relax and de-stress (e.g. breathing exercises, meditation, a walk in the sun, sleep in, relaxation, etc.).  Don’t be surprised if actively managing your stress also helps you lose weight.  

61.  How should you break a fast?

Many people find they experience gut distress and diarrhea when they eat again after fasting for days at a time and have to eat special foods to acclimatise their digestive system to eating again.  However, this is not the intent of Data-Driven Fasting.  We want to optimise your day to day eating routine so you can consume good food to satiety without digestive issues or bingeing when you refeed.  

62.  What is an “extended fast”?  How long is too long?

While you can go for weeks without food, it may not be optimal.  However, for the many people who eat all day, a couple of hours may feel “extended”.  While Data-Driven Fasting is designed to enable you to dial in your daily eating routine (most people land on a regular eating schedule of three/two or two/one meals per day) there is nothing wrong with going 24 or 36 hours without food so long as you are making good choices when you refeed to ensure you are getting the nutrients you need over the longer term.  But you find yourself reaching for the peanut butter, nuts, cream, pizza etc. after fasting, chances are you’ll do better if you are a little less ambitious next time.

63.  Would Data-Driven Fasting be appropriate if I’m active or a bodybuilder?  

One of the challenges for active people is getting enough fuel to recover and grow without eating so much that they add excess body fat.  Our hunger and energy requirements can vary radically from day to day based on the amount and type of activity you do.  

Intermittent fasting can be a valuable tool for active people to manage their body composition, and we have seen a number of very lean people have great results with Data-Driven Fasting to reach their goals.  Data-Driven Fasting is not just for people who are overweight or who have Type 2 Diabetes.  

It’s valuable to refuel if your blood sugars are low so you don’t get too hungry and will be more susceptible to binge later on.  However, given that your blood sugars are closely tied to body fat levels, using your blood glucose as a fuel gauge also enables you to kerb your appetite rather than feeling entitled to eat unlimited amounts of energy that will leave you gaining fat despite all your hard work.

When you are active, your body will crave more energy for recovery and build muscle, and your blood sugars will be affected for a while after exercise.  After a heavy workout, your muscles can become more inflamed and demand more glucose to help with the recovery process, so don’t be too concerned if you see elevated blood sugars after a heavy workout.  However, if your blood sugars are trending up rather than down when you’re well-rested and recovered, it’s a sign you are over-fuelling.   

64.  Can you drink alcohol while fasting?

Alcohol tends to decrease your blood sugars.  Alcoholics often have very low HbA1cs.  However, this is not necessarily a good thing.  

  • Due to oxidative priority, your body has to burn off the alcohol before glucose and fat, so you will downregulate the release of glucose (and fat) into your bloodstream until your body clears the alcohol that it cannot store.   
  • We tend to make poorer food choices after drinking a significant amount of alcohol that will keep your blood sugars elevated for longer.  
  • At seven calories per gram, alcohol is energy-dense (compared to fat which is nine calories per gram and carbs and protein which contain four calories per gram).  
  • Alcohol often comes with plenty of carbs and other yummy things that are easy to overdo.  
  • While alcohol knocks you out and some people think they fall asleep faster, you don’t get into REM sleep as quickly because your metabolic rate is elevated while you burn off all the high-octane energy from the alcohol.  So, not only will you feel dehydrated and have a hangover, you won’t have slept as well either.  
  • Alcohol is effectively empty calories (similar to sugar, refined grains or oils).  It contains lots of energy with very few nutrients, so it won’t help you on your quest to maximise nutrient density.  

65.  Will I lose weight more easily if I’m insulin sensitive?  

There is a common misconception that being insulin resistant or having Type 2 Diabetes makes it harder to lose weight.  However, the opposite is true.  We become insulin resistant because we are obese, not obese because we are insulin resistant.   This distinction is critical.  

People who can gain a massive amount of weight are often highly insulin-sensitive, with normal blood sugars, even with much higher levels of body fat before they develop diabetes.  People who are lean are typically much more “insulin sensitive”, meaning that they can quickly gain weight (both muscle and fat) when they eat.  Weight loss generally slows as someone becomes leaner, and hunger increases to prevent starvation.  

It takes a massive amount of discipline and self-restraint for bodybuilders to diet down for a bodybuilding show, and many of them regain it extremely quickly afterwards due to their uncontrollable appetite.

As a general rule, someone who is obese is more likely to be insulin resistant and have elevated blood sugars, with excess energy overflowing into their bloodstream.  It’s hard for them to gain more body fat because their adipose tissue is already full.  However, once they drain the excess energy from their bloodstream, they will be able to lose body fat.  Their pancreas is likely struggling to continue to produce enough insulin to keep their excess energy in storage.  As they lose body fat, their insulin levels will reduce, and they will become more sensitive to the effects of insulin.  

66.  Could extended fasting harm your healthy appetite signals?  

Your body LOVES routine.  While daily intermittent fasting can be useful to compress your eating window to give your metabolism and digestion time to rest, repair and use up your glucose and fat stores without continually being topped up, there is a risk that your lizard brain will get confused if you subject it to extended periods of fasting or irregular meal timings that are out of sync with your healthy appetite signals.

If you go out and eat a big meal late on Friday night, sleep on Saturday and Sunday and eat then go back to work on Monday with an early breakfast your body gets metabolic jet lag.  Your circadian rhythm is tied to not only the sun and light signals but also your activity and eating patterns.  

As a general rule, it is ideal to eat the majority of your calories when the sun is up, and if possible, earlier in the day when your body is primed to use the energy rather than store it.  But regardless of whether you practice early time-restricted feeding (eTRF) or one meal a day (OMAD) at dinner, your body prefers a regular eating schedule.  

Similarly, your healthy appetite signals can become confused when you skip eating for days at a time and then eat to satiety on other days.  As you push through hunger on some days, you tell your lizard brain that food is scarce, so next time you eat, you will likely eat more than you need to to ensure that you have enough food for the next self-inflicted famine.  Hence, we strongly recommend you develop a regular eating routine guided by your blood sugar or weight.  

67.  Is my thyroid stopping me from losing weight?   

Many people who are over fat and have metabolic syndrome have some level of thyroid dysfunction.  However, similar to insulin, this is often a result of obesity rather than the cause.  

If you are taking medication for your thyroid, you should continue to have your thyroid-stimulating hormone (TSH) monitored by your health care team and adjust your medications as required.  

Your thyroid is a central governor for your metabolism.  Similar to insulin, your pituitary gland will ramp up its production of thyroid-stimulating hormone to rev up your metabolic rate if you have more energy to burn off.  As you lose weight and reduce your blood sugars, your body won’t need as much thyroid-stimulating hormone to keep your metabolism elevated, and your levels may decrease.  

It’s also worth noting that nutrient density is critical to healthy thyroid function (particularly selenium, iodine, niacin, histidine and tyrosine), so prioritising whole-food nutrient-dense meals is also a crucial part of the equation.  

68.  Fasting is stressful 

A little bit of stress can be beneficial (i.e. hormesis or eustress).  Our body likes consistency and routine, but complete stagnation and monotony lead to weakness and atrophy.  So, you want a little bit of stress to continue to grow, but not too much all at once.  

The seasons (e.g. autumn, winter, spring and summer) naturally forced our body to go through cycles of different food availability and bulking and cutting.  Any good workout routine involves periods of progressive overload interspersed with rest and recovery.  

However, too much stress beyond the point that we can adapt and recover (i.e. distress) is not good and forces our body to take evasive action.  Data-Driven Fasting ensures that our eating routine is punctuated by just enough stress to keep our body moving forward towards our goals.  As we incrementally lower blood sugar, weight, fat, insulin resistance and improved metabolic health will follow.  

69.  Should I fast when I’m sick?

Sickness, infection and inflammation can affect your blood sugar.  You may need more food for recovery, or you may lose your appetite while your body takes some downtime to heal when you are unwell.  

When you’re sick, you can take a break from testing your blood sugars and follow your regular eating routine or just listen to your healthy appetite signals and eat when hungry.  You can always pick back up where you left of with Data-Driven Fasting once you recover.  

70.  How to “build your fasting muscle”

Lots of people talk about “building their fasting muscle” as if they just need to do it longer and harder to get more benefit.  Sadly, when it comes to fasting or exercise, the majority of people go too hard too early and burn themselves out before they experience the real benefits or develop a sustainable routine that will provide significant benefits over the long term.

You need to make sure you are doing the right exercise, not overdoing it, getting adequate recovery (i.e. nutrient-dense refeeding) and getting the minimum effective dose by measuring your progress.  

Data-Driven Fasting provides a systematised approach to ensure you are covering all these critical elements to ensure long term sustainable success.  

  • By measuring your waking and after-meal blood sugars, you can make sure you are doing the right exercise (i.e. finding the right balance between delaying your first meal and finishing eating earlier).
  • By prioritising high satiety nutrient-dense food, you maximize your recovery from fasting, so you are ready to go ahead sooner.
  • By waiting to eat when your glucose is below your trigger point ensures you are getting the minimum effective dose without overdoing it.
  • By tracking your blood sugars, weight and waist, you will ensure you are making progress and being rewarded for your effort as you progressively lower your premeal trigger.

71.  Do I need to track before every meal or every day?

No.  You don’t need to log every meal for Data-Driven Fasting to work.  However, when you start out, you will get the maximal benefit from measuring more often to guide your routine and learn about your unique metabolism.  After a while, you will build new habits and get a better appreciation for your real hunger.  

You may lock in your Main Meal and only test before your Discretionary Meals.  If you are on holidays or can’t test for a few days, you can pick up where you left off without feeling like a failure.  You will quickly find if you have overfilled your fuel tanks while you weren’t tracking.  If you have already drained a little bit of your excess fat stores, it won’t take too long to catch up to Your Personalised Trigger value.

72.  How long will it take to train my hunger? 

People with elevated blood sugars tend to have more dysregulated hunger signals and find it harder to judge their true hunger, hence monitoring blood sugars is a great way to train your hunger if you are overweight or have elevated blood sugars.  A number of fascinating studies (e.g. Training to estimate blood glucose and to form associations with initial hunger) have shown that people can learn to predict their blood sugars from their feeling of hunger.  

After several weeks of testing blood sugars, people can get a good feel for their blood sugars when they are actually hungry based on their symptoms (e.g. gastric symptoms, abdominal sensations or mental fatigue).  

Once you can predict your blood sugar and rate your hunger based on your symptoms and wait until you are actually hungry to eat you will be ready to wean yourself off the measuring and rely on your hunger signals.  

73. What if my blood sugars rise again before I eat?  

The goal of hunger training is simply to verify that your hunger is real based on your blood sugars.  If your blood sugars are below Your Personalised Trigger when you feel hungry, then it means you have successfully depleted the glycogen in your liver and have started to burn our body fat.   You have validated your hunger, you have used up the energy in your system from your last meal and are ready to refuel again.  

Some people have found when they test again before they eat that their blood sugars may have risen while they prepare their meal.  It is perfectly normal for your body to release glucose into your bloodstream:

  • when it anticipates food is coming, 
  • as part of the normal process of maintaining stable blood sugars, or 
  • if it gets stressed by low blood sugars and hunger.  

The “secret” here is not to test again.  Just go ahead and eat if you are hungry and your blood sugar has dipped below your trigger.  This is one of the downsides to using a continuous glucose monitor for hunger training as it can provide more data than necessary.  The goal is to leverage the minimum effective dose of measurement to ensure you are moving progress rather than becoming overwhelmed by data.  

74.  Can I reset my trigger?

Your “current trigger” will progressively ratchet down (not up).  If you have a big weekend where you eat too much or a party, you will likely need to fast longer or more often to catch up and reach your trigger point.  Before long, you will learn to think twice before overfilling your fuel tank again.  

If you backslide for a couple of weeks and you find you can’t catch up to your trigger without excessive hunger that leads to bingeing, you can overwrite your calculated trigger value with a slightly higher value.  Still, consistency is the secret to long-term success.  Ideally, there won’t be too many times that you have to reset your trigger.  

75.  Should I eat less protein if I have diabetes?

Some people mistakenly try to achieve perfectly flatline blood sugars by reducing both their protein and carbohydrates.  Unfortunately, this often ends in overeating low satiety nutrient-poor high-fat foods which in turn leads to increased energy intake, weight gain and insulin resistance!   

If you are insulin resistant or have elevated blood sugars, there will be more dietary protein ‘lost’ in the conversion to glucose via gluconeogenesis and hence not available for muscle protein synthesis.   To make up for the protein that has been lost to glucose, your appetite will increase, and you will consume extra energy to get the protein you need.  

Hence, rather than avoiding protein, it is crucial for people with Type 2 Diabetes or any degree of insulin resistance to emphasise a higher protein percentage (by reducing easily accessible energy from carbohydrates and fat) until they can optimise their body composition and become more insulin sensitive.  

79.  Is there a certain number that indicates I am “in fat-burning mode”?   

You are always burning a combination of fat and glucose.  When you’re active, you burn more glucose and more fat at rest.  If you have a lot of glucose in your system, your body has to burn through the glucose first (due to oxidative priority), so you won’t be burning as much fat.  

Counterintuitively, when we measure their respiratory quotient, we find that people who are obese and insulin resistant tend to be burning primary glucose at rest, even though they are a LOT of fat in storage.  

As you wait until your glucose is dropping below your personalised trigger before you eat, you will ensure that you are burning more fat at the end of each fasting period.  As you progressively lower your trigger, you will be burning more fat and less glucose as you drain the excess glucose that is backed up in storage.  

As your premeal blood glucose levels reduce, your body will progressively burn more fat, particularly at rest.  As your fasting glucose trends towards more optimal levels, you will be burning more fat.  So long as you are not supplying excess dietary fat, you will be burning body fat when your glucose levels are low.

80.  Tips for blood sugar testing

If you’re new to testing your blood sugars, here are some tips to make it easier.

  • While most people use their fingers, they are very sensitive.  You can get blood from anywhere.  You can use the sides of your finger or the outside of your forearm where there is less fat and less sensitive. There may be slight differences in values with your finger, but that doesn’t really matter as long as it’s consistent.
  • If you do use your fingers, make sure you rotate between then to stop one finger getting too sore.  
  • Make sure you have a sharp lancet (they hurt less). You don’t have to change it all the time, but if you feel it’s hurting more than usual, try a new lancet.
  • Some meters (like the Contour Next One) will allow you to add a bit more blood if you don’t get enough the first time without wasting a strip.
  • You only need enough blood to get a test result, so dial back the lancet depth to minimise pain but still get enough blood.  
  • Make sure you don’t have food on your fingers when you test. We’re not trying to measure the sugar on the outside of your body.
  • It will also help if you have warm hands, are well hydrated.  You can try shaking your hands to bring more blood to your fingers first.
  • Before you prick your skin, it’s a good idea to rub your skin a little bit first to mobilise the blood.  This allows you to have a lower setting on your lancet and potentially less pain.
  • Some people find the first few tests difficult, but it quickly becomes easier.  

81.  If my blood sugar is below my trigger when I wake should I eat?

No.  The goal of Data-Driven Fasting is to eat when you are hungry and require fuel, not just when your blood sugars are below your trigger.  

If you are above your Personal Fat Threshold, you will likely see more elevated blood sugars in the morning.  However, some people find that their blood sugars are below their trigger when they wake and wonder if they should eat. 

Even if your blood sugar is below your trigger when you wake, you should wait until later when you would normally eat when you are hungry, and your blood sugar is below your trigger.  If your blood sugar tends to rise through the day, locking in a protein-focused Main Meal earlier in the day and then using your premeal trigger for other discretionary meals may also work well.   

82.  How do I get my Data-Driven Fasting Spreadsheet?  

We’re eager for people to find their initial trigger value.  To get started you can download the free baselining spreadsheet here.  The full spreadsheet with Hunger Training and all the other phases is available with the Data-Driven Fasting 30 Day Challenge or the Program.

83.  Is my blood sugar meter really accurate? 

Some people take multiple tests and find that they are slightly different and wonder how accurate their meter is.  Others take multiple tests with multiple meters and get confused when they get different readings.  

If the number you see on your meter isn’t what you expected, there’s no harm in taking another measurement, particularly if you didn’t get enough blood initially and had to add more to get a result.  At the same time, keep in mind that no measurement is perfectly accurate.  We recommend that you don’t continue to take multiple measurements and second guess the numbers.  

While there will always be variability with any measurement, you can still use the data to force the trend in the direction you want.   If you feel particularly hungry, you are free to override the blood glucose trigger (but make sure you record the value that you see on your meter in the spreadsheet).  Remember, you only need to see premeal glucose below your trigger more often than not to see progress.  

84.  What if my blood sugar doesn’t drop below my trigger point for a whole day?  

As you start to make progress and burn through your excess glucose stored in your liver and your muscle, your body will start to find a new normal.  You should be aware that once you have lost your initial water weight (stored with the higher levels of glucose in your body), the initial progress may slow.  Some days you may not see your blood sugar fall below your trigger point and wonder if you’re allowed to eat at all today?  

This is where you should fall back to your Main Meal and Discretionary Meals.  If your blood sugars are above your trigger but you are still hungry you can choose to eat one less meal than normal today.  

  • If you usually have three meals, you can choose to have two.  
  • If you usually have two meals, you can drop back to only Your Main Meal.  
  • We don’t recommend you try to skip full days of eating as you may risk becoming overly hungry and binging on less optimal foods when you refeed.

As you do this, you should continue to see your body weight, body fat and waist measurements continue to trend down.  In time your blood sugars (which can vary due to a range of other factors) should follow.   

85.  Aren’t meal choices important too?

Yes.  What you eat is arguably more important than WHEN you eat.  But food choices also play a big role in how long your blood sugars will take to return to baseline.  

  • High-fat foods and meals will keep your blood sugars stable after meals.  However, high-fat foods and meals tend to provide fewer nutrients and satiety per calorie.
  • Meals with more fast-digesting non-fibre carbohydrates will raise your blood sugars quickly, but they may also return to below baseline more quickly.
  • Foods that contain both fat and carbs with low protein will fill both your fat and glucose fuel tanks and allow you to eat more.  Hence, they will keep your blood sugars elevated for longer.  
  • Foods with a higher percentage of protein are harder to overeat and won’t raise your blood sugars significantly (in fact, they may reduce them).  Your blood glucose will return to below target more quickly.

Data-Driven Fasting always works best when paired with nutrient-dense high satiety foods.  

86.  Why do my blood sugars rise when I don’t eat?

This is perhaps the most common question when people start delaying their meals.  They expect blood sugar to be drained immediately.  But the reality is that it can take time to drain the glycogen from the liver.  When you don’t eat, your body will continue to refill your blood glucose from the stored energy.  

Before the days of convenience foods and refrigerators, this rise in blood sugars would usually fuel you to go in search of food to ensure you don’t starve.  But if you’re patient, over time, you will draw down the stored energy in your liver which will lead to lower blood sugars.  It will also pave the way for a reduction of the fat in your blood and the fat stored on your body.  

Slightly higher blood sugars in the early stages are not a bad thing as it is better than having all your stored energy remain in storage, so you feel lousy and tired and more compelled to eat.  

87.  Protein requirements in fasting

As shown in the chart below from Quantitative Physiology of Human Starvation: Adaptations of Energy Expenditure, Macronutrient Metabolism and Body Composition (Hall, 2012), in the early stages of extended fasting your body will use approximately 400 calories (100 g of stored protein). Over time, this decreases to 250 calories (60 g of protein).

While protein requirements do tend to decrease during extended fasting, the amount you still use is not insignificant. If you fast for a couple of days every week, you will need to make up for that protein across the week to prevent loss of lean muscle over the long term.

When you refeed, your body will seek out food to replenish calories and nutrients, especially protein. If you do not prioritise protein when you refeed, your appetite will step in and ensure you consume enough calories to get the protein your body needs.  In Data-Driven Fasting, we recommend people track their weight and body fat levels to ensure that they are losing fat and not lean mass over the long term.  

This is likely the main reason that so many people find themselves losing and regaining the same weight when they attempt extended fasting without attention to food quality when they refeed.  It can be challenging to get adequate protein over the long term without excess energy when we gravitate to energy-dense food when we refeed after fasting for more extended periods.  

Our analysis suggests that two meals a day with an emphasis on protein at the first meal is ideal for long term weight loss without losing lean mass.  Regardless of how long you chose to fast, nutrient focused refeeding (especially protein) is critical to your long-term success.

88.  How low can I go? 

Some people see their blood sugar start to fall quite quickly when they begin with Data-Driven Fasting and wonder how low is too low.  

The first thing to understand is, if you feel at all unwell (e.g. overly lightheaded, weak, etc.), you should eat.  However, because Data-Driven Fasting simply encourages people to delay or skip their meals (i.e. not extended fasting), we don’t tend to see people having the issues with Data-Driven Fasting that you tend to see with more prolonged or extended fasting.  

These charts show a compilation of pre-meal vs waking glucose values (in mmol/L and mg/dL) from people who have completed the Data-Driven Fasting Challenge.  We do see trigger values down as low as 3.1 mmol/L (56 mg/dL).  However, 4.0 mmol/L (72 mg/dL) is probably a reasonable lower limit for a premeal trigger.     

At the lower end, the trigger value of 3.5 mmol/L was from Mark who lost 9.4 % of his body weight in the first 30 Day Challenge (see Mark’s magnificent DDF mass loss!) while eating a high percentage protein on a carnivore style diet.  The lowest value of 3.1 mmol/L is from Resh, who is quickly reversing her diabetes while also prioritising protein.  Her other markers of insulin resistance are improving rapidly!  

While these values are much lower than what passes for ‘normal’ in a world that is awash with diabetes, there is no issue so long as you are not taking medications that drive your blood sugar lower (e.g. insulin) and you feel OK.  

People generally feel fine with lower stable blood sugars so long as they are not dropping rapidly.  However, as your blood sugar lower slowly over time, your body will gradually transition to more burning fat, so you will be getting the energy you need from your stores.  If the fat in your diet is not too high, this will be predominantly fat from your body.  

In addition to your trigger value, you should also keep an eye on your other markers (e.g. weight, waist to height, body fat, how you look and feel) and transition to Phase 5 – Maintenance, when you feel you have reached a point that you are comfortable with an, is sustainable to maintain over the long term.  

89.  How quickly will I make progress with Data-Driven Fasting?  

While fasting typically leads to people to lose and regain the same weight over and over, we have seen people make excellent progress in the Data-Driven Fasting Challenges as people as they fine-tune their eating schedule.  Using your blood sugar as a precise guide as to when you need to refuel vs when you can wait a little longer seems to provide much better results than other methods of weight loss and blood sugar control.   

As shown in the chart below, DDF challenge participants lost an average of 5.1% (up to a maximum of 12.2%) of their body weight.  The average weight loss was 4.1 kg (or 9.0 lbs) at a rate of 1.3% per week as people chased a lower premeal blood sugar value.  

More importantly, with a focus on nutrient-dense refeeding, participants in the 30-Day Challenge were able to lose an average of 14.4% of their body fat in 30 days at a super impressive rate of 3.6% per week.  On average, participants who completed the challenge lost 3.9 kg of body fat (8.7 lbs).  

Waking glucose dropped by an average of 16% from 5.7 mg/dL (102 mg/dL) to 5.1 mmol/L (92 mg/dL).  As you can see from the chart of before and after waking glucose, the people who had the highest blood sugar dropped the most.  In some cases, waking blood sugar rose during the challenge as people were losing weight rapidly. However, waking blood sugars will likely stabilise at a lower level once they stop losing weight.    

Premeal blood glucose trigger dropped by 15% on average.  Participants started with an average premeal trigger of 5.4 mmol/L (or 98 mg/dL) and ended with a premeal trigger of 4.7 mmol/L (or 85 mg/dL).  

It seems that waiting until your blood sugar returns to below your personalised trigger value is a powerful way to ensure a negative energy balance for sustainable long-term fat loss and diabetes reversal!  

90.  Will I lose too much lean mass when I fast?

While many people simply focus on weight loss, loss of metabolically active lean mass (i.e. your muscles, organs etc.) is an unfortunate reality for most people when they maintain an energy deficit over the long term.  

Some people invoke the magical powers of hormones that supposedly stop you losing any strength or muscle or say that you grow muscle by using it (even if you avoid eating protein and focus on high fat ‘ketogenic’ foods when you refeed. 

Encouraging people to fast for extended periods, telling them that nutrients/protein doesn’t matter and then saying that they shouldn’t binge when they refeed is like taking someone to the top of a mountain (where the air is thin), making them hold their breath for longer than they ever have and telling them to not gasp when they take another breath.

If you want to build strength and resilience in anything, you need progressive overload, ideally with some form of measurement to make sure you are making incremental progress and adapting.

Prioritising nutrient-dense foods and meals (that happen to have a higher protein %) is similar to practising breath holds and then putting an oxygen mask on when you breathe again.

In Data-Driven Fasting, we encourage people to track their body fat in their tracking spreadsheet using at home bioimpedance scales to understand their long-term trend in loss of fat vs lean mass.  While bioimpedance scales care not as accurate as a DEXA scan (or an autopsy), tracking changes in your body composition over time can still be useful and cost-effective.  

If your lean mass is trending down faster than you would like it to or your body fat percentage is increasing, you can review your diet to ensure you are consuming adequate protein when you eat.  Some form of resistance training to tell your body that you want to grow and even keep the muscle in spite of the fat loss is also ideal.

In the Data-Driven Fasting Challenge, we saw people lose an average of 0.31 kg (or 0.68 lbs) of lean mass over the 30 days.  While most people lose some lean mass, some people gained a moderate amount of lean mass during the challenge despite the weight loss.  

However, this is in the context of an average fat loss of 3.9 kg (8.7 lbs) and a reduction in body fat percentage of 7.8% over the four weeks.  As shown in this next chart, the average body fat percentage decreased from 37.4% to 34.5% over the four weeks.  

91.  Are my blood sugars before or after I eat more important?

Most people focus on reducing their blood sugar rise after they eat by reducing carbohydrates and sometimes even protein.  However, it’s the average of your blood sugar across the day that is really important.  

The period after you eat is only a small portion of the day.  High-fat meals that cause a smaller after you eat can also keep your blood sugars elevated for longer.  So may not actually help you achieve a long-term reduction in your average blood sugars across the day or help with fat loss and reduction of your insulin levels.

As outlined in the sequence below, modifying your diet to reduce the rise in blood sugars after you eat is only one step in the journey.  Delaying your meals until your blood sugars are below your trigger is critical to ensure your average blood sugars are decreasing and you are losing body fat.  And, finally what you eat is also important.

Data-Driven Fasting uses the following process to help you control your blood glucose and body fat.  

  1. First, dial back refined carbs to achieve non-diabetic blood sugar variability.  Your blood sugar should not rise more than 30 mg/dL or 1.6 mmol/L after meals.  Most people following a low carb or keto diet are already achieving this.   
  2. Next, we fine-tune your timing using Data-Driven Fasting to continue the fat loss journey.  This is typically two or three meals for more active people or one or two meals for people who are less active.  However, the limit here should be one Main Meal per day with a single Discretionary Meal on days you are meeting your blood sugar target (i.e. OMAD+).  
  3. If you are not achieving weight loss or your waking blood sugar is not decreasing with a Main Meal and a Discretionary Meal, look to increase your protein percentage, food quality and nutrient density by reducing the foods that provide the most fat in your diet.   

This table gives some guidance as to when you should consider changing your focus.  

StepLimit DescriptionWhen to progress 
1. Stabilise blood sugars< 30 mg/dL or 1.6 mmol/L rise after mealsReduce processed carbs to achieve healthy blood sugar stability. When BG rise after meals is < 1.6 mmol/L or 30 mg/dL
2. Meal timing/intermittent fasting One Main Meal with one Discretionary Meal (OMAD+) Reduce the number of times you eat per day.   When average meals per day is less than 1.5.  
3.  Increase protein % by dialling back fatWork up to 40-50% protein.Slowly increase protein % (by reducing dietary fat) until weight loss re-commences. When you have reached goal weight, body fat, waist:height or waking glucose.  

92.  How can I plan ahead with DDF?

In the first few days of Hunger Training, you will use your blood sugar to delay your meals and decide when to eat.  Later you lock in your Main Meal with Discretionary Meals based on your blood sugar.  

However, while your blood sugar right now is an excellent indicator of your hunger and whether you need to refuel, the reality is that it can take a number of days or even weeks to drain your fuel tanks once they are overfull.  

So, if you find your blood sugar is about your trigger today, then it will be a safe bet that you should plan for one less meal tomorrow.  Before long, you should fall into a new route that you can follow most of the time, regardless of your testing.  You can use your testing to ensure what you are doing is continuing to work for you and decide if you need to refine it further.  

94.  How will fasting affect my sleep?

Many people find their sleep improves when their blood sugars start to stabilise with Data-Driven Fasting.   

Not eating too much or too late enables your body to rest, repair and recover rather than working all night to store all the food you ate just before you head off to bed.  Getting adequate protein is critical to provide the amino acids that form the precursors to melatonin which promotes healthy sleep cycles (e.g. tyrosine, tryptophan, etc.).

However, at the other end of the spectrum, as you get leaner, your sleep may also become worse.  Your body sees starvation as a threat to survival and releases cortisol and ketones to keep you alert so you can go out and hunt (rather than lay down and starve).

Most people who have dieted down to very lean levels find their sleep deteriorates.  Not sleeping well is not sustainable, and your cravings for energy-dense food will increase as your body does whatever it can to get to a level of body fat that it is more comfortable with.

So, if you find you are not sleeping well, it might be wise to back off for a little while and be more gracious with yourself.  Try maintaining your weight for a little while until you feel OK again.  You can always come back to Data-Driven Fasting when the time is right.  

While we may have dreams of being lean and looking like fitness models, it’s hard to achieve and even harder to sustain.  So, if you are approaching healthy blood sugar levels, BMI, body fat or waist to height and your sleep is in the toilet, it might be a sign that you need to practice maintaining your weight for a few weeks or months.

95.  What should I log if I’m only eating my Main Meal and a single Discretionary Meal or OMAD?

If you get to the point where you’re eating a Main Meal and a Discretionary Meal (if your premeal glucose is below your trigger) you only need to log your blood sugar before your Discretionary Meal if you eat it.  This means you may not log a blood sugar every day.  This will work perfectly fine, and Your Personalised Trigger will continue to update if your blood sugar before Your Discretionary Meal continues to drop.  

While we usually find people settle on a schedule of three/two or two/one meal per day, DDF will also work with one meal a day (OMAD).  For OMAD, treat your one meal a day as your Discretionary Meal and simply log your premeal blood sugar when you eat it.  If you can’t reach your trigger for a day at your usual mealtime you could choose to skip it and wait for your blood sugar to come down tomorrow.  Keep in mind though, with OMAD, food quality becomes even more important, so you should do what you can to maximise food quality and nutrient density to ensure you get what your body needs from food over the long term.

96.  What if my waking blood sugars aren’t dropping?

While we find most people see their waking blood sugars drop over time, they don’t always fall in line, and sometimes they increase despite weight loss, reduction in waist measurements and a falling Personalised Trigger.  

As your insulin levels start to drop and your weight is in free fall, your liver will release more stored energy into your system for use as fuel (which is a good thing).  You don’t need to be concerned if all the other measurements are falling into line.  This is sometimes known as physiological insulin resistance or adaptive glucose sparing.  

One method of testing insulin resistance is the HOMA-IR which is a function of your fasting glucose and fasting insulin levels.  If your glucose is high and your insulin is high, you’re in trouble.  But if your waking glucose is moderate and your insulin is low, then you’re fine.  Best of all, if your fasting glucose and insulin is low, then you are definitely insulin sensitive.   

97.  Does DDF work best with a particular diet (e.g. low carb, keto, vegan, plant-based)

DDF will work perfectly fine with a low carb or low-fat diet.  Low-fat foods may raise your blood sugar quickly, but they will also return to baseline more rapidly than with a high-fat meal.  Foods high in starch such as potatoes are hard to overeat so long as they are not combined with added fat.  Some people find that they get the lowest premeal blood sugars on a low-fat diet with whole foods.  Conversely, low carb foods will cause a smaller rise in your blood sugars after you eat but may stay elevated for longer.   

The problem comes when we consume foods that are a combination of fat and carbs together (with low protein).  These foods tend to be easy to overeat (hyperpalatable) and will keep your blood sugar and insulin levels elevated for much longer, so it will take longer for your blood sugars to drop back below Your Personalised Trigger.  

If you wanted to mix it up and get more variety in your diet, you could even alternate between low carb and low-fat meals (particularly if you are insulin sensitive and do not see a significant rise in glucose after you eat).  Allowing your blood sugars return to below baselining before you eat ensures that you are not filling both your fat and glucose fuel tanks at the same time.  

The Data-Driven Fasting 30 Day Challenge 

The Data-Driven Fasting 30 Day-Challenge is a structured approach to optimise your intermittent fasting to align with your goals, preferences and routine.

Over the 30 days, you will learn to optimise your health, gain control of your blood sugars and ensure healthy body fat levels to give you the best chance for a long, healthy and vibrant life!

The Data-Driven Fasting 30-Day Challenge will guide you through the process of optimising your fasting routine, including:

  • Baselining – Identify Your Current Trigger that you will use to identify genuine hunger and when you need to eat to refuel.
  • Your current foods/meals – Learn how the foods you currently eat affect your blood sugar – which ones leave you satisfied and which ones lead you to eat more than your body requires.
  • Hunger training – Learn to delay eating until your blood sugar is below Your Current Trigger to make sure that you eat only when you need to refuel. This will ensure that you are lowering your blood sugars and burning body fat.
  • Curb your late-night binging – Use your waking blood sugars to identify if you are eating too late.
  • Main Meal vs Discretionary Meals – Identify the Main Meal you will use to anchor your eating routine and ensure you get enough nutrients. Based on Your Current Trigger, you can then treat the others as Discretionary Meals to meet your energy needs as required.
  • Optimise your eating routine – Lock in your new habits to guarantee you are moving towards your goals.

What you will get:

  • 30-day program to guide you to optimise YOUR fasting routine to ensure you achieve your goals.
  • The Data-Driven Fasting app to track your progress and fine-tune your intermittent fasting routine.
  • 130-page manual complete with detailed instructions and answers to 99 frequently asked questions.
  • A workbook that you can use to reflect on your learning during the challenge.
  • Weekly Live Q&A sessions where you can ask all your questions and get extra support.

Best of all, we get to do this in an interactive community forum where you can share your journey and ask lots of questions.  

Sign up for the next challenge at

88 thoughts on “How to use your blood sugar as a fuel gauge for weight loss and blood sugar control”

    • That’s the point of using your current average blood glucose level. You start from where you are currently at. By eating only when your blood glucose us less than YOUR average you will make sure you are not over eating,

      • I just use the average on my meter. I was also entering it into a spreadsheet for a while but it’s hard to do every day and takes time. Using the blood glucose meter is instant and current.

      • If insulin is perpetually elevated the blood sugar would still appear relatively low. For people with metabolic syndrome a blood sugar of 90-100 might appear “not too bad” for them but could just be suppressed by their high basal insulin levels. This is why I think testing ketones is more useful. Higher ketones I think means low basal insulin levels in your body. Sometimes a slightly higher blood sugar of 100-120ish for a person with the metabolic syndrome who is attempting to improve via IF is more showing that basal insulin is coming down. The trouble with BG is that it could be high for many reasons, low for many reasons and it could be in flux either rising or falling. Insulin is the real issue and a BG meter does not tell you anything about insulin as most obese people although chronically hyperinsulinemic (they have body fat so they have too much insulin in their system) are not always diabetic! They may get T2 later in their lives but young obese people maintain normal or very close to normal Bs. Doesn’t mean they are healthy. They are insulin resistant and produce ever more insulin to maintain relatively normal BG. This is pre-pre-diabetic. It is my opinion that anyone obese is pre-pre-diabetic, even if they have normal blood sugars. I am not fat shaming. I am post obese myself. All the people who said “you are not unhealthy” and “you are the way God made you” and “we are all different” were totally wrong.

      • I agree Danyelle. If you do have high blood glucose levels I think it’s useful to use IF or LCHF to get those down to normal levels. I mentioned in the article, once you get your BGs to normal you can add ketones or better yet track your glucose : ketone ratio which is a really useful estimation of your insulin levels, not just blood glucose.

  1. This comment from Raymund Edwards is worth repeating:

    “I FAST two days most weeks (last week I did 4) I consider up till 7 DAYS an intermittent FAST , over 7 days I consider a Therapeutic FAST ( I have done three of these , 12 DAYS , 21 DAYS and 43 DAYS – you get good at it by doing it)

    I do the short fasts every week mostly and longer fasts twice a year (that is 7 days or over)

    FASTING DAY = no breakfast go to bed FASTED
    FEEDING DAY = protein rich breakfast

    I FAST WELL (no breakfast go to bed FASTED)
    and I FEED WELL (focus on proteins and nutrients)

    FAST is about ketones and their signalling (get them HIGH) in context of LOW BG and INSULIN.

    FEEDING is about amino acids and their signaling .

    imv FASTING is FASTING (what people call IF is just skipping meals) in consecutive days fast – ketones very soon go over 5 /6 ( and even 7 – 8+)

    THAT is FASTING !!

  2. Great article! Thanks Marty and all responders.

    I finally got a ketone/glucose metre (but only the ketone strips at this point).. I have just “fed” after a 3 day fast but my ketones only got up to .8mml even though I’ve been low carb for several months. 30min after my meal my ketones were at .5mml still.. I thought it would have been better than that whilst fasting and worse after eating.. Look forward to getting some glucose strips for my next fast..

  3. Deb–I’ve been keto-adapted for a couple of years, and when a snow storm blew over our town, my ketones DROPPED into the non-therapeutic range! We’re talkin’ .2 and .1–it happens sometimes, and without explanation. My only excuse was weather-related, which is backed up by Dr. Bernstein, who says that low pressure fronts cause the blood vessels to expand, leading to more total blood volume (and more sugar in that blood). I no longer sweat the weather–instead, I just keep on chugging with my meter, cooking and eating the foods that don’t cause much rise, fall reliably back to baseline, and give me the ketone levels I expect (usually 1.0 and above).

    Now Marty’s given me another use for my meter. If you were to combine Marty’s method above with his low-insulinogenic recipes, you’re sure to come out a winner!

    My problem: I fall asleep around 8 each evening, so delaying dinner is problematic, since I check my blood 1 hr. and 2 hrs. post-meal. The final blood check (and ketone check) would have to happen while I was asleep. I choose to delay (or skip) breakfast instead. Now I can put Marty’s method in place as another tool in my arsenal.

    • The weather thing is interesting. There’s been lots of talk lately about cold thermogenesis etc on metabolism.
      I also wouldn’t use this approach to delay your meal late into the night. Maybe skip dinner or breakfast and see how it goes.

  4. Marty, you know from my comments on FB that I’m concerned that this approach, when not used by diabetics (who it seems to be designed around) may be, or cause, disordered eating.
    And maybe I’m just prejudiced against it for that reason, but for me, I usually eat “lunch” (first meal of the day) after exercising. Exercising always affects my BG the same – BG stays stable or even goes up a few points (no surprise, glucose demand from exercising). I usually eat my first meal after exercising each day, and I am hungry to very hungry at that time. My BG meter tells me I have “adequate” BG, but so what? I’m physically hungry at that point. And, I’m in my eating window, coming off a 16-hour fast with exercise at the back end of it. It seems to me that waiting an hour or two (or -?), at great personal discomfort, is questionable value. This is especially true considering that, for me, eating at this point (LCHF) then always makes my BG go DOWN in the subsequent hours.
    Strong physical hunger to me simply trumps this approach, at least in the context of being LCHF long-term.
    So maybe this approach is not for everyone. Just sharing my own experience here. But, cheers and more power to those people empowered to improve their health with this approach.

    • Thanks Wendy. Fasting is certainly not for everyone. And the idea of this approach is to slowly and incrementally bring glucose levels down rather launching into a dramatic long fast that may be unrealistic. As noted in the article exercise will affect your blood glucose levels as will stress, sleep and a bunch of other things that are more important than intermittent fasting. Definitely important not to use it as an approach to starvation, but I do think paying attention to the blood glucose meter makes more sense than calories or scale weight.

  5. Marty, is there a recommended protocol for when to do BG readings? Should it be fasting, before each meal, after each meal (how long?).

    • Depends what your goal in doing the blood glucose measurements is. Taking your waking blood glucose is a good way to keep track of your overall insulin sensitivity. If you’re following this protocol you’d be taking glucose readings before your meals. If you wanted to find out whether what you just ate worked for you you would take a measurement an hour or two after your meal (obviously the lower the better). If you’re gunning for this approach the aim is for the overall average to be coming down over time.

  6. Today on LC Conversations over at JM’s, they discussed hunger as a mood. I struggle with hunger out of boredom, but remind myself to go find something to do instead of standing in front of the open fridge looking for something to eat. Am I really hungry? My stomach says no, my meter says no, but my head says YES! So I go scrub, vacuum, or iron something…

  7. Anyone in Aus – went to buy Glucose strips for my Optium Neo the other day and was asked for Medicare card.. was a bit confused, guess there is a “diabetes database” or something.. anyway, they were too expensive, so didn’t’ get them.. Do you have a fav place to buy the strips on line as I’m in a Regional Area. Will be in Adelaide in a few weeks if there is a chemist anyone there..

    • I get mine off ebay. $70 at chemist too dear, $27 ebay for 100 much better. Shop around and they usually post free.

    • Deb, there is a Govt. subsidised scheme called National Diabetes Services Scheme which provides strips etc for diabetics at a cheaper price. So that would have been why they asked for a Medicare card or there is a NDSS card which has to be presented to get the cheaper price. The ketone strips are not subsidised and they are nearly a dollar each!

  8. I’ve come across this new product called keyasmart. Blood glucose plus keytone both from same strip.
    Check it out at

      • I understand breath ketones is the most accurate form of monitoring ketones is it not? Ketonix is a device I purchased a couple of years ago out of Europe….Diet Doctor now recommends this and I have found it to be excellent. An initial outlay of not a lot from memory, but once purchased, that’s it…no strips to buy!!

  9. Marty, following on from our comments exchange just now on Reversing Diabetes, I didn’t want to totally hijack that thread so continuing here..😊

    I’m told by my (progressive) GP here that I am not T2DM …..yet.
    Looking at the work of Kraft which Ivor Cummins has so wonderfully brought to light, I would say I am definitely diabetic… what say you please looking at these my latest path results?
    HbA1c: 5.6
    Glucose fasting: 6.3
    Insulin fasting: 18.0 (down from all time high 35.3 July 2014)
    Trig: 3.25
    Cholesterol also problematic.

    TIA,thanks kindly
    Eileen Janeke

    • Eileen, no you haven’t 🙂 My mom is 75 and she brought her blood sugar under control (HbA1c from 11 to 6.3, still a bit to go) with LCHF and a little bit of fasting within 3 months. She’s feeling so much better, more energy, clearer thinking. We thought she was going senile when she really suffered from glucose-induced brain fog!

  10. Hi Marty, I’m so pleased to have come across your blog. This is such interesting information. Awesome stuff. A question: when you’re talking about your ‘average’ blood glucose level; what time of the day or how many hours before or after food are you measuring this? Thanks for clarifying. Katrin, Canberra.

    • For me it’s just the average on my meter. I test a few times a day. It’s useful to eating in the morning and before or after meals. No need to get caught up on the number or timing though, just make sure the trend is in the right direction. So glad you like the blog and it resonates with people!

      • Hi Marty….just found you! This is a terrific blog and site! I have been following LCHF and IF for a couple of years now and lost about 18kgs a couple of years ago….but am really having a problem shifting the final ten or so kgs. I was diagnosed with T2D four or so years ago and cured that very quickly by cutting carbs and reducing my weight….(early LCHF methinks!). My problem is that my oestrogen levels are high and I think that is what has me still be insulin resistant,which I am sure is what is preventing further weight loss – this from further research! I have been following IF for a couple of years now – 16 8 hour window protocol and have just now begun undertaking longer fasts – I’ve only done two so far – one 60 hours, the other 40 with the 16 8 hour on the other days. It was one of the first times my BSs got into the 4s! Question: should I just keep on with this protocol to get my BSs down lower? I guess it takes time? And given BS levels are not a real indication of insulin resistance,how do I check if I have overcome hypernsulinemia…or indeed if this is even possible? Many thanks….and GREAT blog!!

  11. Just discovered this post and although I’m not diabetic I just started taking my wake up blood glucose reading to determine how much my body is healing. I typically do a 3-4 day fat fast (~350 calories per day) every other week. I alternate those weeks with weeks that have two 24 hour fasts and one 42 hour fast. If I changed things based on my BG reading, how would it work exactly? I only do a reading once a day. If my reading is higher than my average I don’t eat for that whole day? Then I’d assume the next day I’d likely be below my average so I’d eat two meals that day? Am I understanding that correctly? I’d assume this method then wouldn’t have me doing multi-day fasts, correct?

    • I don’t think the exact routine matters as long as your glucose or weight at the end of the fasting period is lower than the period before. If you are not going in the right direction you would try to eat less when you do eat, extend the fasting period or fast more frequently. That way you can find the routine that suits you best. If you only want to test once per day you would make the decision to fast based on your glucose or weight at the same time each morning.

  12. Thank you for this information. FYI: There is a typo “….People with Type 1 Diabetes following Dr Bernstein’s protocol try to keep heir…”

  13. Dear Marty
    I’m doing an experiment to get into ketosis. But I’m finding it hard to lower blood glucose. Even following a ketogenic and doing intermittent fasting diet.
    Dinner 8:00 pm
    –Gorduras: 95,60g (74%)
    –Carbohydrates: 8,75g (3%)
    –Proteínas: 68,63g (23%)
    After 26 hours of fasting Flashing: glucose 98 mg / dL
    After 42 hours of intermittent fasting: glucose 107 mg / dL
    After 48 hours of intermittent fasting: glucose 91 mg / dL (0.6 mmol ketones / L)
    End of fasting.
    I ask:
    – Will I have to increase the fast time to go into ketosis?
    – Where does this blood glucose, even fasting?
    – The liver or my own body fat?
    – Blood glucose is related to the circadian cycle, increases during the day and decreases at night?
    Thanks for listening.
    (This post was translated from Brazilian Portuguese by Google, sorry errors)

    • It can just take longer to drain your body’s glucose stores, so keep at it as much as feels good. Intense exercise will also help. Yes, the body can make some glucose from protein or fat if it really needs to.

  14. this is great Marty…but im still confused on what time I would use to establish my 7 day average. If i use wakiing BG, that is dawn elevated, then that number will have me eating all the time as by 9 am the dawn thing has worn off. Should I use a number later in the morning but before eating to find a more accurate BG average?

  15. ok thanks Marty…I wonder is it too much to ask to have a copy of the spreadsheet you used…Im hoping to do this and track my results. Im a cyclist and would like to fast and this approach seems it would better align with the energy requirements.

    • without worrying about spreadsheet the simplest way might be to just look at the average glucose level on your blood sugar meter for the past 7 days and then simply wait to eat until you BG is below that average. if that average every did drift up you could maintain the lowest levels your eating trigger if you wanted to be particularly disciplined.

  16. The chart you reference from was done on rats. In vivo metabolism in humans shows that glucose is very rarely stored as fat; it only occurs in extreme (abnormal) carb overfeeding conditions. So the chart is misleading in that respect.

    Also, the statement above the chart (“Insulin keeps fat stores locked in storage”) is misleading. The whole theory by Taubes/etc of insulin being the enemy is wrongheaded. An energy deficit is the only absolute requirement for weight loss.

    In humans, insulin’s significant role is as a brake, so yes, it inhibits lipolysis. However, that also means that if insulin is not doing its job (whether due to lack of insulin, or insulin resistance), then lipolysis is really high and available to be burned off. In that sense, a diabetic person is actually in a prime position for weight loss. All they really need is a calorie deficit. (I just think too many people think losing weight is all about insulin, when it’s really not.)

    • David,
      The insulin hypothesis lowers my weight and insulin. It explains the way my body works.
      The calories model just doesn’t seem to work for me and many others. It sounds good, but the results are not there.
      What should work is not something I think about. What does work gets my vote. Jim

  17. Hi there,

    I’ve been doing IF since the beginning of this year for 5 days a week. I’m following the 16:8 methodology. After listening to a podcast by Robb Wolf, I’m curious in testing my glucose levels. How should I go about this since I’m already doing IF?

  18. Hi there,

    I’ve been doing IF since the beginning of this year for 5 days a week. I’m following the 16:8 methodology. After listening to a podcast by Robb Wolf, I’m curious in testing my glucose levels. How should I go about this since I’m already doing IF?

  19. Marty, what would you suggest, (for this method to be most effective) the frequency of testing BG levels? I’ve been only testing first thing in the morning (I’m not diabetic, although I think I may have insulin resistence and dawn phenomenon), not testing on days when I know I had too many carbs the day before and on fast days my readings are lower. So I see how I can Infuence my 7 day average depending on how often/when I test. I like the concept of this approach and really want to give it a try.

    • Just testing in the morning makes sense if you are going to skip eating for the day. You just need to keep winding down your target so you have as much fasting as you can reasonably tolerate.

      • What about the days I eat? Record the BG testings that I use to see if I can eat? For example, yesterday after getting out of bed, I tested and the number was higher than my 7 day average, so I didn’t eat. I tested two hours later and it was lower than my 7 day average, so I ate. I should record all tests? and test every morning minimum? (normally I wouldn’t test this morning because I had some dessert with dinner last night, so I’m sure the number won’t be great). Sorry for the questions…

  20. I have been eating LCHF for 3 months now, doing IF for most of it (because I am not hungry in the morning, it just happened without effort My first meal is usually between 12:00 – 14:00, with my last being around 19:00 – 20:00).

    I have been losing steadily (started with 25 kg to loose, and have lost 10 in 3 months).

    I eat 20-25 g carbs and keep my protein around 70-80 g and the rest of my calories from fat, to satiety (usually around 100g – it fluctuates). And my food sources are green veggies, meats and eggs. I have gone dairy free, and use olive oil, coconut oil, ghee (so not 100% dairy free) and coconut cream in my coffee.

    Anyway, my question is about my blood sugar.

    When I go to bed my blood glucose is 90-92, and when I wake up it is 96-99 (once it was 107, but that was after very little sleep and I was exhausted). And I don’t understand where the rise is coming from.

    After 3 months of eating LCHF surely my glycogen stores are reduced? If I am understanding what is quoted here from Dr. Fung, the rise is blood sugar in the morning is related to released glucose from glycogen stores).

    What am I am not understanding?

  21. Hello Marty – Thank you very much for this article. I have been disappointed to have elevated FBG (Dawn Phenomenon?) and A1c. I have been a long time IF (19:5) devotee. It was suggested to me to incorporate an earlier eating “window” which I did, and not eating after approx. 3 pm. Upon implementing this, I immediately experienced dramatic improvement, (i.e., lower avg. BG numbers and lower morning FBG as well), but these beneficial effects started to fade after a few weeks as the numbers began going upward. It was then suggested to me that follow the “glucometer as fuel gauge” protocol you have pioneered. My first serveral days of doing this were productive. Whereas in the past I might have eaten after X hours of my initial eating, (but still within my admittedly arbitrary time-duration eating-window) I now found myself waiting until my BG would drop below my 14 day avg or to some more desirable number. When I was wanting to eat hunger-wise, my BG might have been ~100 mg/dl, but waiting another 1-2 hours, it would drop to the mid or high 80s which, again, were numbers I had not typically seen for years. I have some issues I hope you will please be so kind as to opine on: 1) When I exercise my numbers go up, even if I’ve been fasting and the numbers were dropping before the exercise. I love to exercise and believe it is beneficial, but this effect results in me needing to fast so much longer. What to do about scheduling exercise? 2) I want to continue my early eating window “experiment” but with high morning readings and a tendency for those reading to ascend unless and until I eat, what would you suggest as far as the “conflict” between eating early and waiting for the BG to drop? 3) Finally, 🙂 eating this way ultimately creates timing where my window’s are much shorter even though I’d like to continue enjoying the non-BG benefits of IFing. Any thoughts on that? The courtesy of your time, attention and wisdom are greatly appreciated! Eddie

  22. I would greatly appreciate thoughts on how to incorporate fasted exercise into this “glucometer as fuel gauge” approach. Is it suggested to wait until BG is below recent average to exercise? I tend to exercise fasted in the a.m. I have elevated BG in the a.m. but exercise seems to either elevate it further or prolong the period before it begins to descend. However, “skipping” morning exercise and waiting until evening, (after I’ve broken fast) is much more difficult for me on a practical level. (i.e., work, family, etc.) Thank you!

    • It’s more that you don’t want to be doing really strenuous exercise if your blood sugar is really low. You don’t have to be low do excercose.

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