Since we started the Data-Driven Fasting Facebook Group in May 2020 and throughout the Data-Driven Fasting 30-Day Challenges since then, we have received a LOT of questions from people trying to make sense of their blood glucose.
As people hesitantly began learning the hows? and whys? of blood sugar testing, we fielded the same questions so often that we developed an extensive array of Frequently Asked Questions (FAQs).
The essence of Data-Driven Fasting is simple and works best when you don’t overthink and second-guess it. All you need to do is follow the guidance from your blood sugar meter.
But tracking their blood glucose tends to make people curious and full of questions. As a result, we’ve worked hard to answer them to provide a deeper understanding to empower you to comprehend your fascinating metabolism and tweak the process once you have mastered the basics.
Feel free to use this exhaustive compendium as a searchable reference (Ctrl+F) as you chase your trigger in the Data-Driven Fasting 30-Day Challenge.
Once you understand the various things that can affect your blood sugars, you’ll be able to ‘hear’ the signal from your blood glucose and ignore all the noise. While the details may appear complex, our ultimate end goal is simplicity.
Once you become acquainted with your true hunger signals and make peace with your survival instincts, you will no longer need to rely on your blood sugar meter as a crutch.
Be patient! It’s allowed to take some time. You will reach your goal much faster if you follow the process and don’t stress or try too hard.
- 1.1 How Is Data-Driven Fasting Different from Other Popular Fasting Methods?
- 1.2 How Is Data-Driven Fasting Different from Calorie Counting?
- 1.3 Are There Any Added Benefits from Extended Fasting?
- 1.4 How Is Chasing Your Trigger Different from A Fasting Window?
- 1.5 What Is An ‘Extended Fast’? How Long is Too Long?
- 1.6 How Is Data-Driven Fasting Different from The Fast-Mimicking Diet?
- 1.7 Would Waiting a Little Longer Be Better?
- 1.8 Could Extended Fasting Harm Your Healthy Appetite Signals?
- 1.9 Will I Be Getting Enough Autophagy with Data-Driven Fasting?
- 1.10 Why Do People Do More Than One Challenge?
Most approaches to fasting encourage you to not eat for days at a time in the hope of reducing insulin and driving autophagy.
In contrast, Data-Driven Fasting focuses on the long-term trend with shorter bursts of restriction driven by personal intuition to ensure your blood glucose and weight are moving in the right direction.
Like any intelligent fitness training routine that balances exercise and recovery to ensure beneficial adaptations, Data-Driven Fasting ensures that short periods of energy deficit are balanced with nutrient-dense feeding to achieve long-term progress. It’s much easier to maintain your diet quality if you don’t push to the point that you are ravenously hungry. By balancing bouts of fasting and nutrient-dense feeding, we optimise the long-term trend to move towards our goals.
Rather than adopting an arbitrary eating window that may (or may not) work for someone else, Data-Driven Fasting enables you to fine-tune your eating routine to your unique metabolism, schedule, and activity levels, which vary from day to day.
Rather than focusing on open-ended deprivation, DDF shows you precisely when you need to eat. Rather than “Data-Driven Fasting”, many people have suggested it should be called Data-Driven Eating Using Your Blood Glucose as a Fuel Gauge.
Managing calories in vs calories out sounds simple, but it is incredibly difficult to implement successfully over the long term. The reality is that all calories count, but only if you can accurately count ALL the calories (which we can’t!).
Tracking is inaccurate, our energy needs change over time, and our lizard brain often finds a way to trick us into eating more. Our subconscious survival instincts also don’t like to be controlled by an external force for too long which can prompt psychological disorders to develop.
Data-Driven Fasting respects the conservation of energy by using your blood glucose as a fuel gauge to guide your meal timing to ensure that you are in a negative energy balance and moving towards your goals.
Data-Driven Fasting not only uses your blood sugars to ensure you are achieving a negative long-term energy balance while still getting the nutrients you need when you eat. This practice helps improve satiety and avoid overeating when you don’t need fuel.
While there may be benefits of extended fasting, there are also potential downsides. Not many people enjoy abstaining from food for days on end, and it can be hard to fit into a regular family routine.
Even the most respected fasting gurus admit we don’t know what length of fasting is required to achieve the theoretical benefits or the minimum effective dose to produce meaningful results. Is it 24 hours? Or 36 hours? Three days? Seven days? Or maybe 14 days to get the full benefits of autophagy?
Unfortunately, extended fasting does little to teach you to eat well when you do eat and may lead to reduced diet quality, increased fat gain, and muscle loss over the long term. If you cannot control your food quality when you eat again after fasting, you are trying to fast for too long and are unlikely to be making sustainable long-term improvements.
The good news is that most of the benefits of extended fasting can be achieved by dialling in your daily meal routine by prioritising nutrient-dense food choices when you eat to ensure a long-term energy deficit that leads to optimal body composition. Data-Driven Fasting guides you through optimising meal timing and enables you to focus on getting the nutrients you need with a sustainable routine over the long term.
While there is plenty of talk about the benefits of fasting for autophagy, cancer, and Alzheimer’s disease, very few studies are available on humans to validate these theories. There is some research on autophagy in rodents.
However, mice aren’t tiny humans. One day for mice is equivalent to around 40 days for humans. Therefore, the equivalent of a 24- or 36-hour fast in a mouse would kill many people as they starve to death. Another key difference is that, while rats get the same chow no matter how often they eat, humans have the liberty to eat whatever we want when we’re hungry to replenish our energy stores quickly.
You will see plenty of posts on social media detailing the specific times you need to fast to get certain benefits. Meanwhile, the experts in the field still don’t understand the optimal length of fasting to achieve the benefits of autophagy. What we do know, however, is that all the conditions we are most concerned about are vastly improved by achieving and maintaining more optimal body composition.
As shown in the charts below, the relative risk of a range of cancers increases with Body Mass Index (from Quantitative association between Body Mass Index and the risk of cancer: A global Meta-analysis of prospective cohort studies: Obesity and cancer risk).
The images below (from Waist-to-height Ratio Is More Predictive of Years of Life Lost Than Body Mass Index) show that our overall mortality risk increases with a higher BMI.
Many people ask, “How many days should I fast?” But what you really need to know is, “How can I optimise my normal eating to ensure that I am moving towards an ideal body composition and staying below my Personal Fat Threshold over the long term?”
For more details, see:
- Nutrient-Dense Foods and Recipes for Cancer Patients, and
- Can Longevity Be Bought in a Bottle? Thoughts on David Sinclair’s Lifespan.
1.4 How Is Chasing Your Trigger Different from A Fasting Window?
Rather than a rigid window of time where you eat whatever and as much as you want (or can), Data-Driven Fasting guides you to eat when you are hungry and refuel only when your body needs it.
If you eat more than you require, you will simply need to wait longer until you can eat next. You quickly learn not to overeat so you can eat again sooner. While limiting the amount of time spent eating is beneficial, many people manage to consume a lot of energy in a short window, especially if they choose energy-dense lower protein foods.
When guided by their blood sugar, most people progress with Data-Driven Fasting with two separate meals per day. In addition, most people find it much easier to get the protein and nutrients they need with two meals a day compared to one meal a day (OMAD) or more extended fasting regimes.
We see many people who transition from OMAD to two meals a day in DDF find they have increased energy levels, greater satiety and their weight loss restarts after stalling out.
With DDF, we encourage you to ensure your meals are truly ‘window worthy’, so they provide you with the nutrients you need to maximise satiety. Meals with less fat and carbs will help you return to your trigger and increase satiety per calorie.
1.5 What Is An ‘Extended Fast’? How Long is Too Long?
While you may be able to go for weeks without food, it may not be the best way to achieve your long–term goals (e.g., weight loss and improving your metabolic health).
For the many people who eat all day, a couple of hours may feel relatively ‘extended’. Data-Driven Fasting will guide you to dial in your daily eating routine. Most people land on a regular eating schedule with multiple meals each day.
There is nothing wrong with going 24 or 36 hours without food so long as you make good choices when you refuel to ensure you are getting the nutrients you require. Nevertheless, if you find yourself reaching for the peanut butter, nuts, cream, pizza, or other goods, after fasting, chances are you’ll do better if you are a little less ambitious next time.
1.6 How Is Data-Driven Fasting Different from The Fast-Mimicking Diet?
The Fast Mimicking Diet attempts to provide a small amount of nutrients while reducing protein during a multi-day fast. Developed by Valter Longo, the Fast-Mimicking Diet stems from a plant-based belief system that animal protein is bad.
Maximising nutrient density (i.e., getting all the essential amino acids, vitamins, minerals and essential fatty acids you need with fewer calories) will ensure that your body gets what it needs during weight loss to optimise mitochondrial function, prevent the loss of metabolically active lean muscle mass and minimise cravings.
For more details, see Secrets of the Nutrient-Dense Protein Sparing Modified Fast (PSMF) Diet.
1.7 Would Waiting a Little Longer Be Better?
When they start with DDF, some people wonder if waiting a little longer to get a value that’s a few extra points below their trigger would be better. If a little deprivation is good, then more must be better, right?
However, the aim of DDF is simply to validate your hunger and induce an incremental progressive overload on your metabolism by stretching it a little bit further each time to ensure adaptation and recovery.
Recovery is a critical but often undervalued component of any beneficial (hermetic) stress. In DDF, the recovery component is nutrient-dense, high-satiety eating. You don’t want to push your hunger too far to the point that you sacrifice diet quality when you eat again.
We’re all impatient and want rapid results but pushing too hard too early tends to wake your lizard brain, and you end up eating more than you need to and making poorer food choices. Trying too hard in the first week will make it much harder to make consistent progress in the final weeks of the challenge.
In the first few days of the Data-Driven Fasting Challenge, all you need to do is to learn to wait until your blood sugar is below what is typical for you. We want you to get into the habit of testing when you feel hungry and to record it in the DDF App. Once you master the basics, the intensity ramps up as your trigger drops to push you a little more each day, building on your new skills that you developed in the first week.
So, if you’re hungry and your blood glucose is below your trigger, you’re good to eat—there’s no need to be in a hurry or try too hard! In the first few days you will learn to eliminate unnecessary snacking and find an eating routine that works for your life and metabolism. It’s important that you get into the habit of testing your blood sugar to validate your hunger before it gets more challenging.
As you log more pre-meal glucose values below your current trigger, your trigger will decrease to ensure you are continually moving towards your goals of fat loss and optimised blood glucose. If you do this consistently, your trigger will continue to drop. Don’t be in a hurry!
1.8 Could Extended Fasting Harm Your Healthy Appetite Signals?
Many people who have tried extended fasting have reported resultant challenges after losing touch with their healthy appetite signals.
Although we can push through hunger, this often leaves us unable to stop eating when we have had enough food. Your survival instincts are on the alert for starvation again, so your appetite ramps up to make sure you eat more to ensure you never run out of fuel again.
Your body LOVES routine. It can be useful to compress your eating window to give your metabolism and digestion time to rest while repairing and using up your energy stores without continually being topped up. However, there is a risk that your lizard brain will get confused if you subject it to extended periods of fasting or irregular meal timings that are out of sync with your healthy appetite signals and need for food.
If you go out and eat a big meal late on Friday night, sleep on Saturday and Sunday, and then go back to work on Monday with an early breakfast, your body gets metabolic jet lag. Your circadian rhythm is affected by exposure to light and your activity and eating patterns. This rhythm helps to calibrate the schedule that your body follows to regulate its sleep/wake cycle, release hormones, and cue hunger.
It is ideal to eat most of your calories earlier in the day when the sun is up and your body is primed to use the energy. Regardless of whether you practice early time-restricted feeding (eTRF) or one meal a day (OMAD) at dinner, your body prefers a regular eating schedule.
Similarly, your healthy appetite signals can become confused when you skip eating for days on end and then eat to satiety on others. As you push through hunger on some days, you tell your lizard brain that food is scarce and to eat more than you need to the next time you eat to ensure that you have enough food for the next self-inflicted famine.
Hence, we strongly recommend you develop a regular eating routine guided by your blood glucose, not by some arbitrary time on the clock that may have worked for someone else’s lifestyle.
1.9 Will I Be Getting Enough Autophagy with Data-Driven Fasting?
While there is much talk about autophagy (i.e., self-eating or the body’s way of cleaning out old and damaged cells), when we don’t eat, there is very little understanding of the actual length of fasting required to achieve an optimal amount of autophagy.
Even the most brilliant fasting gurus admit that we don’t know the length of fasting required to achieve benefits or the minimum effective dose of fasting to achieve meaningful results. Do you need 24 hours, 36 hours, three days, seven days or even 14 days to get the full benefits of autophagy?
Unfortunately, studies on yeast and worms in a Petri dish aren’t the same as humans living in the real world, who also need to be robust and resilient to survive into old age.
Research by Valter Longo has shown that cycles of 48-hour fasting produce benefits in mice. However, mice aren’t tiny humans. One day for a mouse is equivalent to 40 human days. The equivalent of a 48-hour fast in a mouse (i.e., 80 days) would kill most humans.
We don’t see any fasting studies on autophagy in humans because they would be impossible to do. The reality is that we know very little about autophagy in humans!
People often refer to the case study of Angus Barbieri, who fasted for 392 days and came out thin and healthy. However, they fail to mention the ten young men in their 20s who died after not eating between 46 and 71 days in the 1981 Irish Hunger Strike.
Autophagy occurs all the time, to some extent. However, it is particularly active when we are not overfed and in a negative energy balance over the long term. Too much autophagy can be harmful if you lose precious lean muscle mass when you fast and don’t get enough dietary protein.
Over time, this cycle can worsen metabolic health. Common symptoms of extended fasting without adequate nutrition that can lead to weight loss plateaus include:
- loss of lean mass,
- hair loss,
- dysregulation of healthy hunger signals,
- adrenal dysfunction,
- thyroid disorders, and
- an inherently lower metabolic rate.
While we know little about the benefits of autophagy in humans, we know that achieving a more optimal body composition, body fat percentage, fasting blood glucose, and waist to height ratio are highly correlated with a reduced risk of dying of any cause.
Cumulative small bursts of autophagy followed by nutrient-dense refeeds are more beneficial than occasional multi-day fasts followed by energy-dense, nutrient-poor bingeing that immediately reverses all the benefits of your self-inflicted deprivation. Data-Driven Fasting ensures you get regular doses of autophagy as your critical metabolic markers (i.e., body fat, blood glucose, insulin, etc.) move towards optimal.
Some people join their first Data-Driven Fasting 30-Day Challenge and wonder why there are so many people repeating the process. If it works, why do people need to come back again and again?
Here are a few responses to this question from people who have done more than one challenge:
- To continue to lower my trigger. (Katie)
- When the momentum of the challenge ends, you can slip back without support and interaction. Emotional eating is still a problem for me. (Hazel)
- I’m still working on the mental aspect of accepting the inevitable if I don’t start working on it and improving blood sugars. I purchased the Unlimited Membership with the second round, so all the future challenges are free – so I keep coming back. (Linda).
- It’s not that it’s not enough, but that one learns more with each subsequent challenge. (Trish)
- There’s so much to learn about myself and how my body responds to different foods, meal timings, and exercise that I am still iterating. This is my third DDF challenge and won’t be my last. I seem to have an easier time with DDF than I ever had with WeightWatchers, keto, or any other time I’ve attempted to make lasting lifestyle changes. Probably because it gives me a window into my unique self. (Tim)
- I’ve lost thousands of dollars chasing my weight-loss dreams with programs that don’t work for me. With DDF, I have no excuse. I’ve never known personal data about myself. Now I feel in control of my weight loss. (Tara)
- I like the accountability to myself. It’s easier to slip up when I don’t acknowledge that. I have made good progress with both DDF and the Nutritional Optimisation Masterclasses. I still have a little way to reach my goal, and then I must learn how to maintain it. Maintenance is the hardest part for me. So, I will be back to progress, learn and consolidate. (Tammy)
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