Data-Driven Fasting Challenge: What Did We Learn?

It was a thrill to see people learn as they put the theory into practice in our first Data-Driven Fasting 30-day Challenge.  

It’s fun to see the process through the eyes of people taking the journey, with all their “ah-ha” moments.  

Many of the observations reinforced our previous analysis.  But there were also surprises.  

Check out what we learned! 

Fasting enthusiasts already have very stable blood sugars!

During the first three baselining days, we ask people to check their blood sugars before and after meals.  I was shocked to see how little most people’s blood sugar rises after they eat.  

The average blood sugar rise after meals was only 0.6 mmol/L or 11 mg/dL.  This is well within the normal range for healthy non-diabetic people.  A significant number of people found that their blood sugar dropped after they ate.

As you can see from the chart below, having stable blood sugars doesn’t align with a lower waist:height ratio.  Blood sugar rise after eating doesn’t have any relationship with your BMI or waking blood sugars either.  

This was a surprise to a lot of other people.  The article Want to lose fat? DON’T aim for stable blood sugars! (Why your CGM could be making you fat) got more than 120,000 views in a couple of days!   

Managing your blood sugar data BEFORE you eat takes the guesswork out of the energy balance equation

After baselining, we only required people to track their blood sugars before they ate.  As they tracked their blood sugars, people were empowered to manage their energy balance and make significant progress.  

If their blood sugars were above their trigger point they were to assume that they had enough fuel onboard and could wait a little bit longer before eating.   

If you haven’t yet, you can download our free baselining spreadsheet here to identify your pre-meal trigger.  

The minimum effective dose of learning “on the job”

The daily posts in the challenge delivered bite-sized chunks of knowledge and action at the same time.  

You can read a book on how your metabolism works, but it won’t be any use unless you put it into practice and see how YOUR body responds.

As people act on the information and see how their body responds, the knowledge “sticks”! It all makes sense as new habits are reinforced.

People can predict their blood sugar and train their hunger 

As people learned to listen to their hunger signals, many people found they were able to predict their blood sugar levels.  

The end goal of Data-Driven Fasting is, rather than to make you reliant on your blood sugar meter forever, to put you in touch with your true hunger signals.  

Dropping the trigger slowly is helpful

Our goal is to ensure you get the minimum effective dose of restriction while getting the results you want.  

Slowly ratcheting down your pre-meal trigger is a crucial aspect of the Data-Driven Fasting System.  As you continue to chase a lower trigger value, your weight, blood sugar and waist will follow.  

We initially had the trigger formula set to drop after a full week of logging.  However, while many people were eager to see their trigger drop, they found it hard to keep up with once it fell suddenly.  

Even though they had been really good for the first week of hunger training, they found it hard to keep up with.  Therefore, we refined the trigger formula, so it dropped more gradually after four days.  

Keeping  your inner lizard happy is important 

People learned to respect their inner lizard brain (affectionately known as “Lizzy”).  Your instincts to seek out enough food are critical to keeping you alive.  

After fasting for extended periods, many people find that they end up eating a lot more when they do eat and don’t make the progress they had hoped for.  

By giving our body high-quality food regularly we ensure our lizard brain stays asleep and we can more easily make progress over the longer term.  

People can learn to differentiate true hunger 

Using their blood sugars as a guide, people learned to differentiate real hunger from eating for comfort, pleasure or entertainment.  

Higher protein % leads to lower insulin

Rather than fearing protein, due to its short-term insulin response, people realised that foods with a higher percentage of protein (i.e. less easily accessible energy from fat and carbs) tend to reduce insulin levels across the day.  

A number of the people that had the best weight and fat loss outcomes were pretty much using a Protein Sparing Modified Fast approach that allowed them to minimise hunger, preserve their lean mass and burn fat using their blood glucose as a guide to when they needed to eat.  

Smaller bursts of “fasting” can be more useful than extended fasting 

Not many people enjoy extended fasting.  

While many people believe that they need extended fasting to achieve autophagy or to manage their diabetes, there is no research in humans to tell us how long we need to fast to get benefits. 

What we do know is that achieving optimal blood sugars, weight, body composition and waist to height ratio aligns with health and longevity.  Smaller bursts of fasting over the long term seem to be much more likely to empower people to achieve this, while still getting the nutrients they need when they do eat.  

You can have amazing blood sugars yet still not be losing fat

Managing pre-meal blood sugars is an excellent way for most people to determine whether or not they need to eat.  

But there were several hardcore keto folks who had excellent pre-meal blood sugars but were not losing weight.  

If you are still filling your fat fuel tank, you will not be losing weight, even if carbs are very low.  

You need to dial back your dietary fat intake to allow fat to come from your body.  

Lots of things affect your blood sugar 

People found that many things other than food affect their blood sugars (e.g. stress, sleep, exercise, dehydration, heat, medications and that time of the month for women).  

Once people understood this and had their Main Meal locked in they were better able to manage these blips and get back on track.  

Noticing Increases in blood sugar due to stress or poor sleep is incredibly useful and helps to ensure you manage these other lifestyle factors.  

Front-loading calories and protein seemed to help a lot of people! 

It’s often easier to overeat later at night.  

It’s probably natural that we do this because it would have been a great way for our ancestors to ensure they stored the maximum amount of fat from their food by eating when they were most insulin resistant.  

However, if we want to reduce the amount we eat, lose fat and reverse Type 2 Diabetes, it seems to be helpful to eat more food earlier in the day, or at least when the sun is up.  

DDF helped many people who had stalled  

Data-Driven Fasting proved to be a  useful tool that helped a lot of people dial in their food intake and understand how different foods affected their blood sugar.

Cutting dietary fat is also essential to losing body fat and reducing your blood sugars

Many people found that dialling back their fat intake helped them tap into their blood glucose even more.  

When your body has excess fuel coming in (regardless of the macronutrient) it will prevent you from drawing down on your stored energy.  

It won’t kill you to wait a little longer to eat!

People were reassured by their elevated blood sugar that they didn’t NEED to eat yet, and they could wait a little longer.  

The occasional “treat” won’t kill you

People learned that the occasional indulgence isn’t a sign of failure; that they don’t need to be wracked with guilt because they have “fallen off the wagon”.  They could just follow their blood sugar and get back on with it.  

Two meals can be better than one 

Many people found that two meals a day is better than one.  Our analysis has found that it can be harder to get enough protein and other nutrients when you eat only once, and we tend to gravitate to energy-dense comfort foods.  

Eating window 

Others found the eating window module was helpful to fine-tune their eating routine.  

Works well with the masterclass 

In the end, we found that fasting alone has its limitations.  People realised that food quality is even more critical when they are restricting how much or how often they eat.  While we didn’t plan it that way, we were pleased to see that many people progressed from the Data-Driven Fasting Challenge to our 6-Week Nutritional Optimisation Masterclass to optimise their food choices.  

A CGM isn’t necessarily better 

Continuous Glucose Monitors are becoming more popular.  While these are a godsend for people with Type 1 Diabetes, all the data can be too much for some people and excessive for Data-Driven Fasting.  

It can also lead people to focus too much on minimising their blood sugar rise after meals.  All we are trying to do in Data-Driven Fasting is to verify our hunger with our blood sugars before we eat.  A simple blood sugar meter, with two or three tests a day, is plenty.

Cutting back to less than one or two meals a day doesn’t necessarily help

While it seems intuitive that one meal would be better than two, many people found that they fell into a routine of two meals per day guided by their blood sugars.   

People can do this for the long term

While many people achieved their goal in 30 days, many others decided they want to do Data-Driven Fasting over a longer-term until they achieved their goals.  


Free Data-Driven Fasting 101 Course

Keep reading

Learn more

Data-Driven Fasting Index