Understanding your unique metabolism [DDF FAQ Part 7]

Your body is a fascinating and complex organism that adapts to the stresses of any new environment to keep you alive. 

In the early days, all you need to do is follow the process without overthinking it.  But a little bit of understanding can be a good thing too. 

This section of the FAQs covers the many questions that often arise as people start tracking and trying to tame their blood sugars. 

7.1  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. 

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 reach a trigger value as low as 3.1 mmol/L or 55 mg/dL.

7.2  What is the optimal blood sugar level for fat burning?

You are constantly 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 must burn through the glucose first (due to oxidative priority), so you won’t be burning as much fat. 

Counterintuitively, when we measure respiratory quotient, we find that people who are obese and insulin-resistant tend to be burning primary glucose at rest, even though they have 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 slowly lower Your Personalised Trigger through repeated cycles of fasting and nutrient-dense feasting, you will be burning more fat and less glucose as you drain the excess glucose that is backed up in storage. 

As glucose levels reduce, your body burns more fat.  So long as you are not supplying excess dietary fat, you will be burning body fat when your glucose levels are lower.

7.3  What is a healthy waking glucose level?

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 glucose is in the optimal range, it means:

  • you are insulin sensitive,
  • your insulin levels are low,
  • your body fat can absorb extra energy from 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 a great goal, while a waist to height ratio of less than 0.5 is ideal for both men and women.  Pushing significantly below these levels may not be healthy or sustainable.  However, your fasting blood glucose is an even better indication of whether you are experiencing ‘energy toxicity’. 

You can track your waking glucose in the DDF app as a marker of your metabolic health.  However, it’s not critical to the DDF process and does not affect your trigger.   Keep in mind, too, that you may see your waking glucose increase initially as your insulin drops, your stored energy is released, and you start to lose weight.  Later, once you switch to Maintenance Mode, you may see your waking glucose stabilise at a lower level.

7.4  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, while 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, ensuring your blood glucose is regulated and doesn’t rise too much.  People with Type 1 Diabetes typically see their insulin requirements the lowest overnight and then start to rise a few hours before they wake up as their liver pushes out glucose, ready to fuel for the day. 

However, people with some insulin resistance may find that their blood glucose increases a lot first thing in the morning due to what is known as the Dawn Phenomenon because the glucose release from your liver is not balanced by adequate insulin to keep blood glucose stable.  This image shows the difference in insulin and glucagon across the day for people who have Type 2 Diabetes vs non-diabetic. 

There is no need to eat immediately if your blood glucose is 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 glucose is 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 glucose is not decreasing because you are waiting too long before your blood glucose drops below Your Personalised Trigger, it may be helpful to have a higher protein meal earlier in the day when you start to feel hungry, even if your blood glucose is above your current trigger. 

Having a blood glucose above Your Personalised Trigger does not necessarily mean you shouldn’t eat.  But if you are hungry enough to eat, you should focus on providing your body with nutrients because you know your body doesn’t need fuel (from fat and/or carbs). 

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

7.5  How does that “time of the month” affect blood glucose for women?

Females of reproductive age should be aware that cravings, blood glucose and insulin sensitivity will vary across the month.  Women with Type 1 Diabetes find that their insulin requirements increase in the days leading up to their period and then drop sharply.  Insulin tends to be lowest in the middle of the cycle around ovulation.   

Cravings and water retention (along with associated water weight gain) also 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 glucose 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.  

7.6  Why does my blood glucose fall after I eat?

Some people find that their blood glucose 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 the glucose and fat stores in your liver are depleted after an overnight fast, many people see their blood glucose drop after their first meal.  Any energy they eat goes to replenish the stores in their liver rather than backing up into their bloodstream.     

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 glucose will remain stable.  Blood glucose 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. 

Testing your glucose response to a high protein meal is a useful measure of insulin resistance vs insulin sensitivity and whether you are above your Personal Fat Threshold.  If you see your blood glucose drop after a high protein meal, then you know you’re reasonably metabolically healthy. 

If you see your blood glucose rise, you know you have some level of insulin resistance.  But the solution is not to avoid protein but rather to reduce carbs and fat to reduce your body fat levels below your Personal Fat Threshold.  

7.7  Why would my blood glucose 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 glucose) may see their blood glucose rise after a high protein meal as glucagon kicks in to tell the liver to release stored glycogen.  Insulin is also released to keep blood glucose stable. 

However, if someone is insulin resistant, their insulin does not work effectively, and their blood glucose is not suppressed.  Therefore, insulin-resistant people can see a rise in blood glucose 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 to maintain stable blood glucose.  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 glucose after a low carb high protein meal, then it may be helpful to talk to your doctor to get your fasting insulin and/or c-peptide measured to understand if your pancreas can produce enough insulin to rule out Type 1 Diabetes or MODY (Maturity Onset Diabetes of the Young).  

Rather than avoiding protein in an attempt to maintain flatline blood glucose, 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.

7.8  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. The excess ‘bad bacteria’ associated with obesity (e.g. Firmicutes) die off as they are not continually overfed with nutrient-poor inflammatory foods. The ‘good bacteria’ associated with healthy body weight can flourish (e.g. Bacteroidetes).  

7.9  How is DDF different from Zoe or Day 2?

There is a technological arms race to create a patented system to provide personalised nutrition recommendations based on the analysis of your poop.

Spearheaded by Professor Tim Spectre, Zoe is a technology start-up company that seeks to provide personalised nutritional advice based on analysis of their gut microbiome.  To get your personalised nutritional prescription, you send your ‘poo in the post’ to their lab for analysis.  Additionally, you also test your glucose (using a CGM) and fat response to standardised low fat and high-fat muffins.  While the well-funded Zoe team are publishing fascinating data powered by complex Artificial Intelligence algorithms, this level of testing and analysis level is potentially excessive for most people. 

Day 2 provides a similar service that provides meal recommendations based on your stool analysis.  Their work is based on a 2015 study Personalized Nutrition by Prediction of Glycemic Responses which identified that people could have markedly different glucose response to the same food.  They hypothesised that they could design a diet to stabilise blood sugars based on a complex (and patented) analysis of your gut bacteria. 

While there is no doubt some interaction between your blood sugars, body weight and microbiome, the reality is, it’s incredibly complex.  The experts haven’t yet been able to define what a ‘good’ vs ‘bad’ microbiome profile looks like, let alone what you should eat to make yours look better.

We may never reach the point that anyone can tell you what to eat by looking at what goes down the toilet, no matter how much data or computer power they bring to the task.  Without an intelligent application of a fundamental understanding of how your body uses energy from your food, particularly how your glucose and fat fuel tanks interact, we risk paralysis by analysis and falling victim to garbage in – garbage out (GIGO)

As shown in the figure below from the Zoe PREDICT 1 study, despite the hype, your gut microbiome is NOT a strong predictor of your glucose or fat response to food. 

What we can see from the PREDICT1 study data is that:

  • the macronutrient composition (i.e. the mixture of carbs, fat and protein) of your food has the most significant impact on your blood glucose response to a meal, while
  • the amount of fat already in your blood has the most significant impact on the rise in the fat in your blood after you eat (i.e. if your system is already full of energy there is nowhere for the extra energy to go). 

This aligns nicely with our understanding of how our glucose and fat fuel tanks work in our body.  If your fat stores are full, any excess fuel cannot be absorbed and backs up in the system and overflows in your bloodstream.  

If you eat in a way that gives your body what it needs (i.e. nutrients from food) and helps you attain a more optimal body composition, your gut bacteria will likely look after itself as it continually adapts to the food you feed it.  And let’s be real, how many people are committed enough to continually analyse their poo today to understand what you should eat tomorrow?

While there will always be some variability in your glucose response to the food you eat, our analysis of the Food Insulin Index data gives us a solid understanding of factors that affect our short term insulin and glucose response to foods.   We have used this to identify foods and meals that will allow you to stabilise your glucose to healthy levels.  Rather than prescribing a meal plan and recipes designed for someone else, the DDF app allows you to track your glucose response to the meals you eat to empower you to create a shortlist of meals that you enjoy eating that work for your unique metabolism (i.e.  Your Personalised Optimal 30/30).   

In the Data-Driven Fasting 30-Day Challenge, we use simpler, less invasive and more cost-effective biometrics to guide your dietary choices. 

  1. If your blood sugars after meals rise by more than 1.6 mmol/L or 30 mg/dL, the DDF app will guide you to reduce your intake of processed carbs until your blood sugars stabilise to healthy levels. 
  2. If your waist:height ratio is > 0.5, and your blood sugars are in the healthy range after dialling back carbs, you likely also need to cut back on your dietary fat intake.  This allows your blood sugars to drop more quickly after meals and eat nutrient-dense meals again more sooner.

Not only will your blood sugars and body composition improve as you stop eating too much too often, but your gut microbiome will become healthier too.

7.10  What is the glucose ketone index (or Dr Boz Ratio)?

The Glucose:Ketone Index (GKI) was developed in 2015 by cancer researcher Professor Thomas Seyfried to track cancer patients’ metabolic health when undergoing long-term fasting.  The GKI is simply your glucose (in mmol/L) divided by your ketones (also in mmol/L).  More recently, Dr Annette Bosworth has also popularised the Dr Boz Ratio, which is simply glucose (in mg/dL) divided by ketones (in mmol/L). 

The GKI is based on the understanding that if glucose is low and ketones are high, then insulin levels will be low, and you’re in good metabolic health.  Conversely, when you fast, if your glucose is high and ketones are low, then your insulin levels are likely high, and you have some level of insulin resistance that you need to attend to. 

The problem, however, comes when people don’t differentiate between endogenous ketones (from your body fat when you’re fasting) and exogenous ketones (from the food you ate, added MCT oil, butter or supplements). 

The vast majority of benefits that often attributed to ketosis come from the energy deficit, so if you are jamming in thousands of empty calories of nutrient-poor fats to raise ketones to get a higher GKI or Dr Boz ratio, then you will be driving up your insulin levels as your pancreas has to work overtime to hold all the added energy in storage.   

If you simply chase a lower premeal blood glucose, you will likely be producing plenty of ketones from your body fat – but you don’t need to measure ketones because they don’t give you any guidance about what or when you should eat.   Hence, we strongly recommend you skip the expense and confusion of testing ketones and simply focus on your premeal blood sugars, which will give you the most actionable data.

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

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 much lower levels.  As you do this, your weight and body fat levels will follow. 

7.12  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 sound sleep based on their quantitative data. 

Don’t be surprised if you find you sleep more soundly as your blood glucose starts to decrease because your body is not working so hard to process excess energy overnight. 

But, it’s also 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.  

Your body prioritises burning off alcohol, which can keep your metabolic rate elevated, so try to avoid too much alcohol later at night.  Similarly, protein requires a lot of energy to metabolise. 

In contrast, carbs and fat are metabolised more easily (i.e. they have a lower Dietary Induced Thermogenesis) and thus will give you a better chance at a sound sleep 

There are many benefits in prioritising protein earlier in the day and backloading carbs and/or fat later to top up with the energy you need (but ideally not too much if you are trying to lose body fat and decrease your blood glucose levels). 

7.13  How much should my blood glucose rise after a meal? 

Data-Driven Fasting Primarily focuses on your blood glucose before meals to ensure you are reducing the excess energy stores in your body.  As your insulin sensitivity improves, your waking blood glucose and post-meal blood glucose should also start to trend down. 

If you see your blood glucose 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.  You should either avoid that meal or eat less of it in the future.  Your glucose tank is already full, so you don’t need more carbs.

Many people find that their blood glucose rises 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 when their glucose and fat fuel tanks are not as full. 

You can use the hourly glucose charts in the DDF app to tailor your meal choices and routine to avoid having post-meal glucose values above the upper limit line (i.e. 1.6 mg/dL or 30 mg/dL) most of the time.  Once you master this, you can get on with focusing primarily on your premeal blood sugars and delay your meals to reduce Your Personalised Trigger.  

The rise in glucose after you eat is more a reflection of what you ate, while your fasting blood glucose and your glucose before meals indicate your metabolic health and whether you are over-fuelling across the day.  Most people won’t need to be too concerned about their post-meal blood glucose if they are focusing on nutrient-dense whole foods, which typically don’t contain refined grains or added sugars.  Once you get below 20-30% of your energy from carbs, less is not necessarily better in terms of nutrient density or satiety. 

7.14  Do I need to worry about insulin toxicity? 

Many people focus on insulin toxicity as the “root cause” of diabetes and metabolic disease.  Hence, they see reducing insulin as the end goal. 

However, if you are part of the 98.5% of the population with a functioning pancreas (i.e. not injecting insulin to manage Type 1 Diabetes), 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 their bloodstream, and their blood glucose will drop.  They will feel ravenously hungry and will eat anything and everything until their blood glucose rises 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’, we should focus on managing energy toxicity, and insulin will look after itself. 

The Carbohydrate – Insulin Hypothesis simplistically assumes:

carbs -> insulin -> fat storage

But it is actually 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 glucose, 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 glucose, you will reduce your body fat, which will reduce your insulin levels.  We designed Data-Driven Fasting to keep things as simple as possible by focusing primarily on your blood glucose before meals.  

7.15  How long will it take to train my hunger?

People with elevated blood glucose tend to have more dysregulated hunger signals and find it harder to judge their true hunger.  Monitoring blood glucose is a great way to train your hunger if you are overweight or have elevated blood glucose. 

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 glucose from their sensations of hunger. 

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

When you log your blood glucose in the DDF app, it’s important to take a moment to observe your hunger.  This self-reflection is critical to help you calibrate your hunger signals


Once you can predict your blood glucose 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. 

7.16  What if my blood glucose rises again before I eat? 

The goal of hunger training is to verify that your hunger based on your blood glucose.  If your blood glucose is 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 your 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 glucose 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 glucose, or
  • if it gets stressed by low blood glucose and hunger. 

The “secret” here is not to test again.  Just go ahead and eat if you are hungry, and your blood glucose has dipped below Your Personalised Trigger.  This is one of the downsides we see with people using a continuous glucose monitor for hunger training, as it can provide more data than necessary.  The goal of Data-Driven Fasting is to leverage the minimum effective dose of measurement to ensure you are moving progressively rather than becoming overwhelmed by data. 

7.17  Why does my blood glucose rise when I don’t eat?

This is perhaps the most common question when people start delaying their meals and chasing a lower premeal trigger.  Many people expect blood glucose to be drained immediately when they don’t eat. 

But it can take time to drain the glycogen from the liver.  Before the days of convenience foods and refrigerators, this rise in blood glucose would fuel you to go in search of food to ensure you don’t starve. 

When you don’t eat, your body will continue to top up your blood glucose from the stored energy.  If your liver is already stuffed full of glycogen, it can take a few weeks to deplete.  Don’t be surprised if your blood glucose rises a little when you don’t eat.  It’s actually a good thing.  

But if you’re patient, over time, you will draw down the stored energy in your liver which will lead to lower blood glucose across the day.  It’s only after your blood glucose lowers that your body will start to burn more of the fat in your blood and the fat stored on your body. 

7.18  Why is my waking blood sugar the highest of the day?

If you have plenty of stored body fat, your body will release that stored energy overnight into your bloodstream, even if you follow a lower-carb diet.  Your body can make glucose from protein and even fat to an extent.  If you have excess energy stored in your body, the glucose will back up in your system and overflow into your blood, especially overnight when insulin levels are lower after not eating for a while.

DDF Index 

4 thoughts on “Understanding your unique metabolism [DDF FAQ Part 7]”

  1. “If your liver is already stuffed full of glycogen, it can take a few weeks to deplete. ” Doesn’t your liver only contain a few hundred kcal of glycogen, something like a few hours supply of energy for your body? Why would it take a few weeks to deplete?

    • because it is constantly refilled from your diet and even GNG from the glycerol backbone of your fat stores. it takes a few weeks to drop in a sustainable manner that doesn’t lead to rebound binging because your glucose plummets to below what you are used to.

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