Tracking your progress [DDF FAQ Part 3]

As challengers start to train their lizard brain (e.g. Lizzy or your amygdala) with external data (your blood glucose levels), lots of questions arise.

This section of the FAQs guides you through the most common questions that come up when people start tracking in pursuit of goal weight, body fat, blood sugar or body composition in the Data-Driven Fasting 30-Day Challenge.

3.1  Are my blood glucose levels before or after I eat more important?

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

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

As outlined in the sequence below, modifying your diet to reduce the rise in blood glucose after you eat is only one step in the journey.  Delaying your meals until your blood glucose is below Your Personalised Trigger is critical to ensure your average blood glucose is decreasing and you are losing body fat. 

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 glucose variability.  Your blood glucose should not rise more than 30 mg/dL or 1.6 mmol/L after meals.   
  2. Next, tune your meal 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 glucose target (i.e. OMAD+). 
  3. If you are not achieving weight loss or your waking blood glucose 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 (note: you should have already dialled back your carbs in step 1 above).  

This table summarises when you should consider changing your focus. 

StepLimitDescriptionWhen to progress
1. Stabilise blood glucose< 30 mg/dL or 1.6 mmol/L rise after mealsReduce processed carbs to achieve healthy blood glucose stability.When typical BG rise after meals is < 1.6 mmol/L or 30 mg/dL
2. Meal timing/intermittent fastingOne 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 at least 40% 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. 

3.2  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 December 2020 Data-Driven Fasting 30-Day Challenge lost an average of 5.1% of their body weight over four weeks.  The average weight loss was 4.1 kg (or 9.0 lbs) at a rate of 1.3% per week.

The table below shows the weight loss leader board from the January 2021 DDF Challenge. 

NameStart (lbs)Finish (lbs)Difference (lbs)% change% per week

More importantly, with a focus on nutrient-dense refeeding, participants 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 lost 3.9 kg of body fat (8.7 lbs). 

The table below shows the fat loss leader board from the January 2021 Data-Driven Fasting 30-Day Challenge

NameStart (lbs)Finish (lbs)Difference% change

Greater compliance will lead to faster weight loss.  However, it’s critical to find a sustainable routine rather than pushing so hard that you find yourself bingeing due to excessive hunger, which will derail your long-term progress.   

As your blood glucose decreases in the first week or so, you will also lose a lot of water weight (note: every gram of glycogen is stored with four grams of water).  After this initial loss of water weight and glucose depletion, you will start to burn through your body fat, potentially at a slower rate. 

3.3  Should I track my weight when fasting?

You don’t have to track your weight every day during Hunger Training

Due to water and food changes 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 glucose at the same time will be a struggle mentally. 

Some people love all the data, and daily weighing 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 burnout.  

If you can, it’s ideal to track your weight each morning so you can see the trends.  But if you find it challenging, 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 glucose decreases.  This may be mainly “water weight” (which is stored with the glucose in your liver and muscles). 

3.4  How often should I track my waist?

We recommend that you track your waist circumference each week on Sundays. 

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 above your belly button at the narrowest point of your abdomen in line with your elbows.  The precise 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.  

3.5  What are optimal body fat levels?

During Hunger Training, your pre-meal blood glucose will continue to decrease as you reduce your body fat levels to below your Personal Fat Threshold.  Your blood glucose meter can provide an insight into 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 glucose 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 glucose also starts 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”.  Like a fuel-efficient race car or sprinter, resistant training will help you increase your power to weight ratio so you will use the energy from your food more efficiently. 

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 must maintain a VERY low-calorie intake to avoid rebound weight gain. 

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. 

3.6  What is the best blood sugar level for weight loss?

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

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

3.7  How do I find my Personal Fat Threshold? 

The only way to find your Personal Fat Threshold is to lower your weight to the point that your waking glucose is in the normal healthy range when you are weight stable.   For some people, this may be at a waist to height ratio of 0.5, while others may need to go a little bit lower.   If you regain weight in the future, you can re-start the Hunger Training process to get your waist and glucose levels back in this range.      

3.8  What is the best way to measure body fat? 

Tracking your body fat percentage helps ensure you are losing fat rather than precious metabolically active lean muscle mass.  The last thing you want is to 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 is perfect, but they’re still useful to track your progress. 

  • A DEXA scan is the most accurate but expensive and inconvenient, so you are unlikely to do it regularly. 
  • The Navy Fat calculator is surprisingly accurate (i.e. aligns with DEXA scans) and is based on multiple measurements (i.e. waist, hip and neck, as well as your weight). 
  • The most convenient way to measure your body fat is using bioimpedance which can be measured with most modern scales.  These may not be as accurate as DEXA, but they ensure you heading in the right direction over the long term.  

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 using our Smart Macros Algorithm.  However, body fat measurements are not critical for Data-Driven Fasting.  Your waist measurement and selfies will be adequate if you don’t already have a bioimpedance scale.  

3.9  Can I lose fat and gain lean mass at the same time?

While we have seen several people manage to gain lean mass while losing fat mass (especially if they increase their protein intake), most people will also see a drop in their lean mass when they lose weight. 

The best ways to minimise the loss of lean mass while losing weight is:

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

3.10  Do I have to check my blood glucose before every meal?


While some people love ALL the data, we have designed Data-Driven Fasting to allow people to use the minimum effective dose of testing and tracking to maximise the chance of long-term sustainability. 

In the Data-Driven Fasting 30-Day Challenge, you will identify your Main Meal that you know you eat at a regular time each day (e.g. dinner with your family or your protein-packed breakfast).  You can then use your blood glucose to decide whether you eat at other times throughout the day (i.e. Discretionary Meals).  

3.11 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 developing 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.  It’s critical to build Tiny Habits and celebrate the small successes that will lead to a sustainable change in lifestyle that will, in turn, lead to you achieving your ultimate goal. 

Data-Driven Fasting provides a systematic approach to ensure you address these critical elements to ensure long term sustainable success. 

  • By measuring your waking and pre-meal blood glucose across the day, you ensure 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.
  • Waiting to eat when your glucose is below Your Personalised Trigger ensures you are getting the minimum effective dose (without overdoing it to the point that you will binge due to rebound hunger).
  • By tracking your blood glucose, weight, and waist, you will ensure you are making progress and being rewarded for your effort as you progressively lower Your Personalised Trigger.

3.12  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, you will get the most benefit from measuring more often to guide your routine and learn about your unique metabolism, especially as you start out.  After a while, you will build new habits and get a better appreciation for your true hunger signals. 

You may want to 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 out 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 as long to catch up to Your Personalised Trigger.

3.13  What are the ideal blood sugar levels for weight loss? 

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

If you feel at all unwell (e.g. overly lightheaded, weak, etc.), you should eat.  However, because Data-Driven Fasting only encourages people to delay or skip their meals (i.e. not fast for days at a time), we don’t tend to see people having the same issues that tend to occur with more prolonged styles of 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 30-Day 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.    

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 glucose lower (e.g. injected insulin) and you feel OK. 

Because they have transitioned to burning primarily fat from their bodies, people generally feel fine with a lower blood glucose (so long as they are not dropping rapidly).  

As your blood glucose lower slowly over time, your body will gradually transition to burning more 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 Personalised Trigger, you should also keep an eye on your other markers (e.g. weight, waist to height, body fat, how you look and feel).

If Hunger Training is getting hard, we recommend transitioning to Maintenance until your lizard brain settles down, you are no longer food-focused and are ready for another round of Hunger Training.  

3.14  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 from losing any strength or muscle or say that you grow more muscle 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 not to 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 percentage of protein) is similar to practising extended 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 the DDF app, using at home bioimpedance scales to understand their long-term trend in loss of fat vs lean mass.  While bioimpedance scales are not as accurate as a DEXA scan (or an autopsy), tracking changes in your body composition over time can still be helpful and cost-effective. 

If your lean mass is trending down faster than you would like it to or your body fat percentage increases, 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 despite the fat loss is ideal.

In the Data-Driven Fasting 30-Day 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. 

3.15  Should I record my premeal blood sugars when I don’t eat?

Ideally no.

Your Personalised Trigger is based on the average of your premeal blood sugars over the past seven days.

You may find you take a few extra blood glucose readings as you wait for your blood glucose to drop below your current trigger, especially in the first few days of Hunger Training.

Ideally, you shouldn’t log these in the DDF app to keep Your Personalised Trigger higher than it needs to be.  In time, you will learn how your hunger symptoms align with your blood glucose and not go to the effort of testing until you are actually hungry. 

3.16  What is the ‘upper limit’ on the hourly glucose chart?

The upper limit line on the hourly glucose chart in the DDF app is set at 30 mg/dL or 1.6 mmol/L above your current trigger.

The primary goal of DDF is to wait until your blood glucose is below your trigger before you eat.  However, it’s also useful to dial in what and how much you eat so your blood glucose returns to below baseline quicker.  If your post-meal blood glucose (during baselining) goes above the ‘upper limit’ line, it’s a sign that you overfilled your glucose tank.  If it goes up and stays elevated for longer, it’s a sign that you overfilled your fat fuel tank as well.   You can think of the upper limit and your trigger as ‘lane lines’ to guide you:

  • not over the upper limit after you eat, and
  • just below your trigger more often than not before you eat.

3.17  When should I take my waking blood glucose?

While you can track your waking glucose every day in the DDF app, you only really need to do it:

  • during baselining,
  • in the final three days, and
  • during the eating window stage (i.e. days 11 – 17).

Other than these times, feel free to skip checking your waking glucose if it’s a hassle or you are finding it confusing.

In terms of the time of the day, it should before you eat or drink anything.  Some people like to take it before they get out of bed, but you don’t have to.  You can integrate it with your morning routine of going to the toilet, weighing yourself, taking your blood sugar, coffee/tea.  Again, consistency is key to tracking your progress. 

3.18 How often do I have to test my blood glucose?

For the most part, you only have to test your blood glucose to validate your hunger before you eat.  This could be as little as twice a day and even less if you identify your Main Meal when you eat, regardless of your blood sugar.  We also like you to test your post-meal glucose during baselining and your waking glucose at the start, end and during the eating window stage. 

The table below shows the recommended minimum effective dose of testing and tracking that we recommend during the Data-Driven Fasting 30-Day Challenge.  Additional blood sugars are optional.  Some people like all the data, but eventually, we recommend adopting the minimum effective dose of testing to guide your eating schedule. 

3.19 What are the milestones?

Celebrating small wins along the way is important.  The milestones in the DDF app highlight the successes of small steps along the journey to your goal.

3.20  What should I log if I’m only eating my Main Meal and a single Discretionary Meal?

If you get to the point where you’re eating a Main Meal and a Discretionary Meal (if your pre-meal glucose is below Your Personalised Trigger), you only need to log your blood glucose before your Discretionary Meal if you eat it. 

This means you may not log blood glucose every day.  Your Personalised Trigger will continue to update if your blood glucose before Your Discretionary Meal continues to drop.   

3.21  Will DDF work with OMAD?

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). 

If you are comfortable skipping full days of eating, treat your one meal a day as your Discretionary Meal and simply log your pre-meal blood glucose when you eat it.  If you can’t reach Your Personalised Trigger for a day at your usual mealtime, you could choose to skip it and wait for your blood glucose to come down tomorrow. 

Keep in mind, though, with OMAD, food quality becomes even more critical, so you should do what you can to maximise food quality and nutrient density to ensure you get what your body needs over the long term.  Before resorting to skipping full days of eating, you should try to increase your protein % to 40% or more.

3.22  Can I edit my data in the app if I made a mistake?

Yes.  Go to navigate -> history and edit/delete any of your entries. 

3.23  What if blood glucose testing is getting too expensive or painful?

While using your blood glucose is the most powerful way to understand if you need to refuel, 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 glucose is 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 glucose, it’s ideal to have regular meal times.  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, we guide people to lock in their Main Meal (that you eat regardless of your blood glucose) and treat other meals as discretionary based on your blood glucose. 
  • If you typically have three or four meals per day and find your blood glucose elevated before eating one of those meals, skip that meal and don’t test until the next meal.
  • While tracking your waking glucose is useful to help ensure that you are not eating too late, it can also be confusing when your insulin levels drop and you are losing weight, so your waking blood glucose rises.  So 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.