Getting Ready for the DDF 30-Day Challenge [Data Driven Fasting FAQ Part 2]

This section addresses many of the most frequently asked questions about preparing for the Data-Driven Fasting 30-Day Challenge.

2.1 When Is the Next DDF Challenge? 

We run eight 30-Day Data-Driven Fasting Challenges per year in our Optimising Nutrition Community.  The dates for the upcoming challenges in 2022 are:

  • 1 October 2022
  • 5 November 2022
  • 7 January 2023
  • 25 February 2023
  • 8 April 2023
  • 20 May 2023
  • 1 July 2023
  • 12 August 2023
  • 7 August 2023
  • 7 October 2023
  • 25 November 2023

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

2.2 How Do I Join The DDF Challenge? 

You can join the next round of the Data-Driven Fasting Challenge here.  Once you do, you’ll be invited to join the next DDF Challenge and get access to all the materials, so you’re ready to start. 

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.  If you don’t already have one, some nifty high-tech yet cost-effective blood glucose meter options are available. Accuracy is important because you will be using your glucose to guide your meal timing.  

A great option in terms of features and accuracy is 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 initially squeamish about measuring their blood sugars initially, but once they start, they love seeing the data and want to test more!  This is great initially, but 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 the 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. 

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 in terms of 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 you to swipe the reader (or your phone) across your sensor.  A CGM is great if you already have one, but not necessary for Data-Driven Fasting.

Keep in mind that CGM sensors are not painless to insert, and you will have to change them every week or so.  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 Libre reads significantly lower than an accurate glucometer by around 10 mg/dL.  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 checking blood glucose when you feel hungry and 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 has dropped below Your trigger. 

Excessive focus on minimising the rise of blood glucose after meals often lead people to low satiety, high-fat foods that will slow fat loss from their body. Unfortunately, more stable blood glucose does not align with lower body weight or healthier waking blood glucose. That’s why we focus on reducing your pre-meal blood sugars in Data-Driven Fasting, which 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 eat 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.  Some 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 meal and are ready to eat.  

Remember, the goal 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.  Taking a moment to check your blood sugars works as a pattern interrupt to ensure you are hungry enough to eat.  After a couple of weeks, you will only need to check your blood glucose a couple of times a day.  

A CGM is great if you already have one or you’re a cashed-up biohacker data geek, but it’s not necessarily better for Data-Driven Fasting. We’d rather you avoid the confusion that seeing your blood glucose in real-time often causes.     

If you’re interested in learning more, check out:

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

As a general rule, you should continue taking your medications throughout the DDF Challenge. 

Many people are on metformin (or berberine), which can help reduce blood sugars, which is a symptom of Type 2 Diabetes or insulin resistance).   However, In 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.  However, this needs to be done progressively and carefully. 

Work with your healthcare team to adjust your dosing to ensure that 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 hold body fat and glycogen in storage, injecting insulin to reduce blood sugars can make it harder to lose unwanted body fat.  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 your excess body fat stores, you may need to dial back your basal and bolus insulin.

A predictable routine is critical, even more so if you take diabetes medications. If you radically change your eating pattern by skipping a whole day of eating or engaging in a multi-day fast, your insulin needs will plummet, and you will risk low blood glucose (hypoglycaemia).   In contrast, 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.

2.6 Will DDF Work If I Have Type 1 Diabetes?

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

Many people with Type 1 Diabetes have great success with the Data-Driven Fasting approach, with significant reductions in weight and 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, you can ‘cheat the system’ and rapidly bring your blood glucose down with injected insulin.  

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. 

2.7 Should I Check My Ketones When Fasting?

As you fast for longer, your blood glucose will tend to decrease. This is because your blood ketones (BHB) increase as your body starts to burn 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 be measuring ketones to check that you are burning body fat.  If your blood glucose is progressively decreasing, you will be using more fat for fuel.  

It’s also important to note that, over the longer term, you don’t need high ketones to be burning body fat!   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. 

As shown in the chart below from Optimisers in our Masterclass, people tend to see their blood ketone values increase for a few weeks.  But after that, they continue to decrease as they continue to lose weight. 

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 cycleVirta’s study results also show blood ketones are initially elevated in the first few weeks before returning to baseline as people lose weight and reverse their diabetes.

As with many things, more is not necessarily better when it comes to ketones.  Blood ketones (BHB) that we measure are the storage and transport form of ketones. On the other hand, 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. If your goal is to understand if you use ketones for energy rather than storing them, 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. 

While there has been plenty of excitement over keto in recent years, tracking your blood ketones is unnecessary and doesn’t provide you with 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 because everyone else is doing it or you have some excess cash to burn, save your money and skip the blood ketone testing! 

2.8 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 protein requirements in one meal, it is not easy. 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. 

As a minimum, we recommend hitting the minimum daily protein shown in the table below in the lead-up to the Data-Driven Fasting 30-Day Challenge.  You can track your intake in Cronometer to check.  If you want to dial in your macros, you may find our Macros Masterclass useful once you’ve completed one round of Data-Driven Fasting. 

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

If you have been undereating protein for a while, don’t be surprised if your body weight goes up a little until your muscles hoover up the protein they need. However, if you look at your waist or body fat, you may find that they’re decreasing in number.

Remember, metabolic health is not just about having a lower body weight. This is demonstrated by the before and after photos of the same person at the same weight but with vastly different body compositions. 

2.9 Tips for Blood Sugar Testing

  • While most people use their fingertips to test blood sugar, they can be very sensitive. You can get blood from any less sensitive location, including the sides of your finger or the outside of your forearm, which is less sensitive. You may get slightly different values when you test on different fingers or parts of your body. This is not an issue so long as you are consistent. 
  • Make sure you have a sharp lancet (they hurt less). You don’t have to change it all the time, but try a new lancet if you feel it’s hurting more after a few weeks.
  • Some meters like the Contour Next One will allow you to add more blood if you don’t get enough the first time to avoid wasting a strip.
  • You only need enough blood to get a test result, so dial back the lancet depth to minimise discomfort but still get enough blood. 
  • Make sure you don’t have food on your fingers when you test. 
  • Having warm hands and being well hydrated will also help. Try shaking your hands to bring more blood to your fingers first.
  • Before you prick yourself, it’s a good idea to rub your skin a little bit to mobilise the blood. This allows you to have a lower setting on your lancet and potentially less discomfort.
  • If you get a blood glucose reading significantly different from what you expected, you can retest again. After that, just accept it and move on.
  • There are many other places where you can test your blood sugars (e.g., forearm, side of your finger etc.) that are less sensitive than your fingertips. 
  • If you don’t initially get enough blood, you can push down with the lancet to get a little more blood without pricking again. 


4 thoughts on “Getting Ready for the DDF 30-Day Challenge [Data Driven Fasting FAQ Part 2]”

  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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