Preparing for Success with Data-Driven Fasting

Get ready to embark on an incredible transformation with answers to your most pressing questions about the Data-Driven Fasting 30-Day Challenge. We’re here to guide you through the essential steps and preparations, ensuring you’re fully equipped.

We dive into the critical aspects of the Data-Driven Fasting 30-Day Challenge preparation. Get ready to unleash your full potential with DDF. 

This section of the DDF Manual holds the answers to your burning questions about the DDF 30-Day Challenge preparation. We’re here to guide you through each step, ensuring you’re fully equipped for the transformative journey ahead.

2.1 When Is the Next DDF Challenge? 

We run eight 30-day Data-Driven Fasting Challenges annually in our Optimising Nutrition Community.  

The dates for the upcoming challenges are listed below.   Click here to join the next challenge to access all the materials immediately. 

  • 6 April 2024
  • 18 May 2024
  • 29 June 2024
  • 10 August 2024
  • 5 October 2024
  • 23 November 2024

See the full events schedule in our Optimising Nutrition Community here (including our Macros Masterclass and Micros Masterclass). 

2.3 What Do I Need to Buy?

Blood glucose meter 

In the Data-Driven Fasting 30-Day Challenge, you will use your blood glucose to optimise your intermittent fasting routine. 

Accuracy is crucial because you will use glucose to guide your meal timing.   If you don’t already have one, some accurate, cost-effective blood glucose meter options are available.  

A great option in terms of features and accuracy is the Contour Next or Contour Next One, which comes with a smartphone app to help you analyse your data. It’s everything you’d hope a modern blood glucose meter would be!  

You can even program the app to give you a happy flashing green light when you are below your trigger.  You’ll get a nice dopamine hit from the green light rather than those less-than-optimal comfort foods!

Test Strips

Test strips are often sold separately.  You will need at least 100 test strips for the Data-Driven Fasting 30-Day Challenge and up to 200 if you want to test more regularly.  

Many people are squeamish about measuring their blood sugars initially, but once they start, they love seeing the data and want to test more!  After the first week or two, we encourage people to use the minimum dose of testing required to validate their hunger and live their lives rather than worrying about minor fluctuations in their blood glucose. 

Bioimpedance Scales 

To get the most out of the Data-Driven Fasting 30-Day Challenge, we recommend using a bioimpedance body weight scale that tracks your body fat and lean mass.  Most modern digital scales will do this. There is a range of options that have various features. Many people find the Renpho a great option for consistency and value for money.   

For more info, see What do the numbers on my bioimpedance scale mean (and how can I manage them)?

Tape Measure 

Your waist-to-height ratio is an excellent indicator of your overall metabolic health.  We recommend measuring your waist each week.  A simple tape measure is an excellent investment.

2.4 Would A Continuous Glucose Monitor Be Better? 

Continuous glucose monitors (CGM) are quickly becoming the most sought-after biohacker toy, and here are a few options available. 

The Dexcom is the gold standard for Type-1 Diabetes management, and it sends a reading to your phone or other devices every five minutes. The Freestyle Libre (used by NutriSense and Levels Health) is cheaper but requires swiping the reader (or your phone) across your sensor.  A CGM is fine if you already have one, but it is unnecessary for Data-Driven Fasting.

Remember that CGM sensors are not painless to insert, and you must change them every 10 – 14 days.  CGMs are also not cheap over the long term, especially if you don’t have insurance coverage!

While you can calibrate the Dexcom with your glucometer, you can’t calibrate the Freestyle Libre.  Most people find that the Freestyle Libre reads lower than an accurate glucometer.  People also often see different readings when they change sensors, which throws out the consistency and accuracy of the data, which is important for Data-Driven Fasting.   

The ultimate goal of Data-Driven Fasting is to retrain your appetite by using your glucose to validate your hunger before you eat.  If you can see your current blood glucose all the time, you’re more likely to eat even if you’re not hungry because your blood glucose dropped below your trigger. 

Excessive focus on minimising the rise of blood glucose after meals leads many to swap carbs for low-satiety, higher-fat foods that will slow fat loss from their bodies.  Focusing on reducing your pre-meal blood sugars in Data-Driven Fasting allows you to reduce your insulin and blood sugar across the whole day.

Focusing excessively on your blood glucose rise after meals can drive people to opt for more low-satiety, nutrient-poor, high-fat foods.  While fat does not raise your blood glucose much in the short term, excessive dietary fat will stop your blood glucose from returning to below your trigger as quickly. 

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

Remember, the goal of DDF is to verify your hunger with your blood glucose. If you can see your blood glucose in real-time, you may be tempted to refuel because your blood glucose dropped below your trigger — even if you’re not hungry. 

There are also benefits in the slight hassle of doing the finger prick and recording your blood glucose before eating.  Checking your glucose before you eat functions as a pattern interrupt to ensure you are hungry enough to eat.  After a couple of weeks, most people find they only need to check their blood glucose twice daily.  

If you’re interested in learning more about the pros and cons of CGMs, check out:

2.5 How Do I Test My Blood Glucose? 

While it might seem a little scary the first time, testing your blood sugar is pretty straightforward and painless. 

  1. Insert the test strip into the glucometer.
  2. Use the lancet to draw a small amount of blood. 
  3. Move the test strip to the tiny drop of blood.  The strip will suck up the blood.
  4. Wait a few seconds to get a reading on your meter.  During this time, you can wipe off any excess blood and close the test strip container.
  5. Record the value in the DDF App.

Because you’ll be taking regular measurements, you want to keep it as simple as possible.

  • Most people use their fingers, but other areas (like your forearm) can be much less painful.  While locations can give slightly different glucose readings, you only need to be consistent for DDF. 
  • There is no need to worry about calibration solutions outside a clinical setting. 
  • So long as you’re not testing on your hands after eating or cooking, there’s no real need to wash your hands before every test.  But you should ensure you don’t have food on your fingers when you test. 
  • Remove the end of the lancing device the first time to insert a lancet.  So long as you are not sharing your lancing device, you don’t need to change the lancet after each test.  However, after a few weeks, they can get a bit blunt and, hence, a little more painful, so it is helpful to change the lancet then. 
  • You can dial the depth of the lancet up or down to get just enough blood to fill the test strip while minimising the pain.    
  • Meters like the Contour Next will allow you to add a little more blood if you don’t initially get enough the first time.  You can push down with the lancing device (without pricking again) to get a little more blood.
  • Having warm hands and being well-hydrated will help. Try shaking your hands to bring more blood to your fingers first.
  • Before you prick yourself, you can rub your skin a little bit to mobilise the blood.   
  • If you get a blood glucose reading significantly different from what you expected, you can retest again.  After that, accept it, record the one that makes the most sense, and move on.  Don’t keep testing or second-guessing. 

2.6 How Should I Adjust My Medications When I Start Fasting?

Continue taking your regular medications throughout the DDF Challenge. 

Many people are on metformin (or berberine), which can help reduce blood sugars.   However, during the DDF Challenge, we focus on your pre-meal blood sugars to address the root cause (excess body fat). 

Medications such as injected insulin will help manage the symptoms of Type 2-Diabetes, like elevated blood glucose, but will do little to reverse the underlying cause (energy toxicity).

If you take any diabetes-related medications (e.g., injected insulin, sulfonylureas or glipizide that encourage your pancreas to produce more insulin), you should pay particular attention to your blood glucose as you extend the time between meals.

Many people find they can progressively dial back their diabetes medications as they continue with Data-Driven Fasting.   Work with your healthcare team to adjust your dosing to ensure your blood glucose doesn’t go lower than you feel comfortable (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 glucose returns to normal. 

Because insulin works in your body to store body fat and glycogen, injecting insulin to reduce blood sugars can make it harder to lose unwanted body fat because it pushes your glucose lower, and you feel hungrier earlier. 

Excess injected insulin causes your body to hold fat and glycogen in storage, making you hungrier.  As your blood sugar reduces and your body starts to burn off excess body fat stores, you may need to dial back your basal and bolus insulin.

A predictable routine is critical, especially if you take diabetes medications. If you radically change your eating pattern, your insulin needs will plummet, and you will risk low blood glucose (hypoglycaemia).   However, Data-Driven Fasting will guide you to make incremental changes to your eating routine, allowing you to dial back your medications slowly. 

During this transition period, it may be prudent to dial back your insulin dosing and allow your average blood glucose to run a little higher to avoid lows.  Once your glucose variability reduces, you can tweak your insulin dosing to maintain lower average blood glucose.  

For more details, see:       

2.7 Will DDF Work If I Have Type 1 Diabetes?

Data-Driven Fasting has been heavily inspired by watching my wife and son’s closed-loop CGM-insulin pump system that adjusts insulin dosing based on blood sugar data from their CGMs.  

Many people with Type 1 Diabetes successfully use the Data-Driven Fasting approach, significantly reducing weight and daily insulin requirements.   It doesn’t make sense to eat if your blood sugar is high and if you have plenty of energy already in your bloodstream.  

However, the one caveat is that you ‘cheat the system’ and rapidly bring your blood glucose down with injected insulin.  Unfortunately, this will be counterproductive.  Rather than injecting more insulin to bring your blood sugars below your trigger, Data-Driven Fasting will encourage you to wait a little longer to eat. This will lead to lower daily insulin requirements and improved insulin sensitivity. 

For more on Type 1 Diabetes, see How to Optimise Type-1 Diabetes Management (Without Losing Your Mind).

2.8 Should I Check My Ketones When Fasting?

As you fast for longer, your blood glucose will tend to decrease.  Ketones (BHB) increase as your body burns stored fat for fuel.  The chart below shows how blood glucose and ketones change during a seven-day fast – blood glucose trends downward as ketones rise. 

However, you don’t need to measure ketones to verify you are burning body fat.  As your blood glucose reduces, your body will use less glucose and more fat for fuel.  If you are not overdoing your dietary fat intake, more of that fat will be from your body. 

Ketosis is simply an alternative pathway to fuel your brain and vital organs when you don’t have enough oxaloacetate from carbohydrates and protein to burn the fat in the Krebs cycle.  However, ketosis is less efficient, so after a few weeks or months, your body adapts to a lower-carb diet, and you will see lower blood ketone levels.  Virta’s study results show blood ketones are initially elevated in the first few weeks before returning to baseline as people lose weight and reverse their diabetes.

Over the longer term, elevated ketones are not a valuable indication of your fat burning!   People who carry more muscle and are metabolically healthy have more efficient monocarboxylate transporters, meaning they can more effectively clear lactate and ketones from the blood.  So, as your metabolic health improves, you will likely see your ketone levels decrease as the energy in your bloodstream from fat, glucose, and ketones all decrease. 

The chart below shows that people tend to see their blood ketone values increase for a few weeks.  But after that, ketones continue to decrease as they lose weight. 

More is not necessarily better when it comes to ketones.  The blood ketones (BHB) we measure are the storage and transport form of ketones.  Your level of breath ketones (i.e., breath acetone or BrAce) is a better indicator of whether you are burning ketones rather than forcing them to build up in your bloodstream.  Tracking your breath acetone may be more helpful.  But again, you don’t need to worry about ketones to confirm you are using body fat if you are chasing a lower premeal blood sugar

Tracking your blood ketones is unnecessary and doesn’t provide actionable data because there is no way of knowing if the ketones are from your body fat or the fat in your diet. Sadly, tracking ketones often leads people to consume more fat than they require in the pursuit of ‘optimal ketosis’.  Ketone test strips are also expensive.  So, unless you are curious or you have some excess cash to burn, save your money and skip the blood ketone testing! 

2.9 I’ve Been Doing OMAD/ADF/EF. What Should I Do in Baselining?

There are some nuances to the DDF process depending on previous eating habits.

Some people come to Data-Driven Fasting because their One Meal a Day (OMAD), Alternate Day Fasting (ADF), or Extended Fasting (EF) routine has stopped working for them.

Stalling out on longer fasting routines is common due to a slowed metabolic rate and a loss of muscle mass due to inadequate protein intake.  

While it is possible to get your daily protein requirements in one meal, it is not easy, and few people achieve it.  More frequent eating is less stressful for your body (i.e., less cortisol and less digestive hassle).  Many people find their weight loss restarts when they get more than one meal a day in our Data-Driven Fasting Challenges

We recommend hitting the minimum daily protein shown in the table below in the lead-up to the Data-Driven Fasting 30-Day Challenge (based on 1.4 g/kg LBM).  

height (cm)height (inches)female protein (g)male protein (g)

You can track your current protein intake in an app like Cronometer.  If you want to dial in your macros, you may find our Macros Masterclass

If you have been undereating protein for a while, don’t be surprised if your body weight goes up while your muscles hoover up the protein they need.   However, you may find your clothes fit better, your waist circumference is dropping, and your body fat is dropping.  Remember, metabolic health is not just about having a lower body weight.  


4 thoughts on “Preparing for Success with Data-Driven Fasting”

  1. Question – is the suggested protein per meal? Day? Per week??? – I’m 5’7” or 67”, female – so by this chart I think the suggestion is for 72 grams…per day?

    I purchased a mojo meter and have been trying to get in the habit of charting my BG (& ketones) in the AM and when I get hungry in the afternoon. I typically eat between 3 – 7 pm each day. I’m hoping the challenge will include suggestion for meal prep and what to eat. I struggle with planning. But execute pretty well if I have a clean plan.

    • suggested protein is per day. you should try to hit it on average across the week (even if you’re skipping full days). you will find a bunch of our NutriBooster recipe books and meal plans in the challenge group when you join.

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