WHEN to eat [FAQ Part 4]

Data-Driven Fasting helps you dial in your eating schedule to suit your own unique metabolism and schedule. In this section of the DDF FAQs, you will learn how your body uses the food you eat and how your glucose and fat fuel tanks interact and how to leverage that understanding to achieve your goals.   


4.1  When should I test my blood glucose after eating?

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

The rate your blood glucose rises and falls after a meal will depend on what you are eating and your unique metabolism.  As shown in the chart below, blood glucose rises quickly after a high carb low-fat meal (green line), while it will increase more slowly (and not as much) after a high-fat meal. 

Testing one hour after you finish eating is a good rule of thumb, but you could do some extra testing (e.g. every half hour for two or three hours after a couple of meals) to find out when your glucose levels peak if you’re really 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 glucose 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 glucose rises 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 glucose 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 glucose by more than 1.6 mmol/L or 30 mg/dL AND your blood glucose rises 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. 

While higher fat foods will cause a smaller rise in blood glucose after meals, you need to find the balance between getting adequate nutrition and stable blood glucose.  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 glucose rollercoaster is bad, flatline blood glucose should not be your goal.  Stable blood glucose levels are a symptom of good metabolic health.  While we can achieve stable blood glucose with a low–carb, high-fat diet (i.e. symptom management), diabetes reversal and improved metabolic health require reduced body fat levels. 

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

  • fast-acting carbs will raise your blood glucose quickly, but they may also come down quickly,
  • high-fat meals will help you achieve more stable blood glucose, 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, croissants, milk chocolate, etc.) will fill both your fat and glucose stores and keep your blood glucose 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, so you may even see your blood glucose fall and be able to you can eat again sooner when you are hungry.

4.2  How can I integrate fasting into my 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.

Dinner could then be Your Main Meal, and you can treat the other meals as discretionary.  

4.3  How many meals per day should I eat?  

As you use your blood glucose to guide 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 ravenous, so we often eat more with one meal a day than two meals a day.  It is also easier to meet your vitamin, mineral and 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 glucose) allows them to achieve long term success.  However, if you’re active or 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 one/two or two/three meals per day during Hunger Training. 

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 used to decide between one/two or two/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 meals ensure you get the nutrients you need when you eat and help you feel more satisfied and hence less likely to overeat. 

4.4  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 glucose in the morning and find it is above Your Personalised Trigger, so you will delay eating until your blood glucose come down in the afternoon or before dinner. 

But, later that evening, you find you are even more hungry at night, have less controlled eating and find yourself bingeing again.  This is particularly a concern if you see your waking blood glucose increasing over the long term. 

As you start to lose weight, your insulin levels will drop, and more of your stored energy may be released overnight, so you may actually see your waking glucose rise for a few weeks.  But in time, your waking glucose should start to fall as you decrease the amount of excess stored energy in your body. 

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 more leeway to eat earlier in the day.  Another option is to lock in an earlier meal that you will eat every day.  You can then use your blood glucose 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).  Many people find they alternate between one and two meals per day as their trigger lowers. 

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 low pre-meal triggers who are eating a very high fat “keto” style diet that enables them to consume a lot of calories in just a few meals. 

You can track your food in Cronometer and 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.

Once they get the hang of Hunger Training, many people find it helpful to slowly dial up the percentage of energy from protein (by dialling back fat and carbs).  It’s best not to jump from one extreme to the other, but rather slowly increase your protein percentage towards 40% or more of your calories for maximum satiety and fat loss while minimising loss of precious lean mass. 

4.5  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.  So, 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 glucose is not coming down, it might be worth locking in a protein-focused Main Meal earlier in the day (even if your blood glucose is still above Your Personalised Trigger) so you are less hungry and hence less likely to binge at night.

4.6  If my blood glucose 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 glucose is below Your Personalised Trigger). 

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

Even if your blood glucose is below Your Personalised Trigger when you wake, you should wait until you are actually hungry and your blood glucose is below Your Personalised Trigger. 

If your blood glucose tends to rise through the day, locking in a protein-focused Main Meal earlier and then using your premeal trigger for other discretionary meals may also help.  

4.7  How to interpret your hourly glucose chart

As noted below, your hourly glucose chart can give you a LOT of insights without the hassle of a CGM. 

  1. Think of the trigger line as a sign that you are running LOW and need to refuel. 
  2. You don’t want your BG to go too far below your current trigger, as your hunger will drive you to eat anything and everything (at the expense of food quality).
  3. As you slowly chase a lower trigger, you will continue to deplete your glucose stores sustainably over time.
  4. When you eat, you don’t want to see your BG go above the ‘upper limit’ FULL line. This is a sign that you overfilled your glucose fuel tank and/or your fat fuel tanks are full (i.e. your adipose tissue on your bum and belly), and fuel is backing up in your system. Try to reduce/avoid foods that boost your post-meal above the ‘upper limit’ line. Reducing processed carbs will help here (but don’t simply swap for dietary fat if you want to lose body fat).
  5. If your pre-meal values are higher in the morning than later in the day, you should prioritise protein and nutrients (rather than fuel from fat and/or carbs) in the morning. Higher % protein meals tend to help your BG to go down (rather than up). Conversely, if your pre-meal values are lower earlier in the day, you could add more carbs at your first meal.
  6. If your waking BG is high, you should consider “closing your window” a little earlier and/or eating a little less late at night. However, keep in mind that waking BG can go up initially as insulin lowers and you start to release stored energy.  But in time, it will settle down as you chase your trigger.
  7. If your trigger starts to stabilise at a lower level and weight loss slows, try to dial back dietary fat to allow your body fat to be used. Focusing on protein/nutrients when you eat will help you manage satiety.

4.8  How can I plan ahead with DDF?

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

While your blood glucose 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. 

If your blood glucose is consistently above Your Personalised 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 routine 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. 

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