Since we started the Data-Driven Fasting Facebook Group in May 2020, and throughout six previous Data-Driven Fasting 30-Day Challenges, 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 (“Genius!”) tagged them–wait for it!–FAQs, Frequently Asked Questions.
Feel free to use this exhaustive compendium as a searchable reference (Ctrl+F) as you chase your Personalised Trigger in your own Data-Driven Fasting 30-Day Challenge. Once you understand the various things that can affect your blood sugars, you’ll be able to ‘hear’ your blood glucose’s signals and ignore all the static. (Just as a friendly aside, if it isn’t in the FAQs, it probably isn’t worth knowing. Cheers!)
- 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 to ensure your blood glucose and weight are moving in the right direction.
Just like any intelligent fitness training routine balances exercise and recovery to ensure positive adaptation, Data-Driven Fasting ensures that short periods of energy deficit are balanced with nutrient-dense feeding to achieve long term progress.
By doing this, we ensure that diet quality is maximised (i.e. adequate protein and nutrients) during feeding rather than the energy-dense bingeing that often follows multi-day fasts. By achieving a balance of adequate bouts of fasting and quality feeding, we optimise the long-term trend to move towards our goals.
Rather than adopting an arbitrary eating window that may work for someone else, Data-Driven Fasting enables you to fine-tune your eating routine to your unique metabolism, schedule and activity levels (which can vary from day to day).
Managing calories in vs calories out sounds simple, but it is incredibly difficult to implement successfully in practice 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, and psychological disorders can develop.
Data-Driven Fasting respects the law of conservation of energy but uses 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 balance over the long term but in the short term, it ensures you are only refilling your fuel tanks when you need to, which helps improve satiety and avoid overeating when you don’t need fuel.
This video from Optimising Nutrition advisor Dr Ted Naiman gives an excellent overview of the challenges with tracking calories to lose weight.
While there may be benefits of extended fasting (e.g. no food for three or more days), there are also potential downsides. Not many people enjoy not eating for days on end, and it can be hard to fit into a regular family routine.
Even the fasting gurus admit that we don’t know what length of fasting is required to achieve the theoretical benefits or the minimum effective dose and meaningful results.
Is it 24 hours? 36 hours? Three days? Seven days? Or maybe fourteen 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, fat gain and muscle loss over the long term. If you are not able to control your food quality when you refeed, 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 (with nutrient-dense food when you eat) to ensure a long-term energy deficit that leads to optimal body composition. Data-Driven Fasting guides you to optimise your meal timing and enables you to focus on getting the nutrients you need within 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, there is very little data in humans to validate these theories. There is some research on autophagy in rodents. But mice aren’t tiny humans. One day is equivalent to forty days for humans, so the equivalent of a 24 or 36 hour fast in a mouse would kill many people as they starve to death.
You will see plenty of memes on social media detailing the required time you need to fast to get certain benefits. Meanwhile, experts (like Peter Attia and Eileen White) admit that we know very little about autophagy in humans, let alone the optimal time to get a particular benefit.
What we do know, however, is that all these conditions are vastly improved by achieving and maintaining a 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 for?” 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?”
Rather than thinking in terms of a window (when you can eat whatever and as much as you want), Data-Driven Fasting will guide you to thinking in terms of eating when you are hungry and fuelling only when your body requires it. If you eat more, you will need to wait longer until you can eat next.
While limiting the amount of time you have to eat is beneficial, some people still manage to cram a lot of energy into a short window. Some people in our Data-Driven Fasting 30-Day Challenge have described their ‘fasting window’ as an all-out four-course feast with little regard for what they were eating within their set window.
Many people make significant progress with DDF, with two distinct meals per day separated by 6 to 10 hours (with no snacks in between). 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. If you eat more, you will need to wait longer until you can eat next. Meals with less fat and carbs will help you return to your trigger and increase your satiety.
While you may be able to go for weeks without food, it may not be the best way to achieve your goals over the long term. For the many people who eat all day, a couple of hours may feel “extended”. Data-Driven Fasting will guide you to dial in your daily eating routine. Most people land on a regular eating schedule of three/two or two/one meals per day.
There is nothing wrong with going 24 or 36 hours without food so long as you are making good choices when you refeed to ensure you are getting the nutrients you require. But if you find yourself reaching for the peanut butter, nuts, cream, pizza etc., after fasting, chances are you’ll do better if you are a little less ambitious next time.
The Fast Mimicking Diet attempts to provide a small amount of nutrients and reduced protein during a multi-day fast. Developed by Valter Longo, the Fast-Mimicking Diet stems from a plant-based belief system where animal protein is bad. In contrast, Data-Driven Fasting is more like a Protein Sparing Modified Fast, which prioritises adequate bioavailable protein and more nutrients per calorie during the limited feeding opportunities.
By maximising nutrient density (i.e. getting all the essential amino acids, vitamins, minerals and essential fatty acids you need with fewer calories), you will ensure that your body gets what it needs during weight loss to optimise mitochondrial function, prevent loss of metabolically active lean muscle mass and minimise cravings.
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.
Eating less often and with fewer calories makes it harder to get the nutrients your body needs. You need to find the right balance that suits you to continue making steady progress toward your goals.
So, if you’re hungry and your blood glucose is below Your Personalised Trigger, you’re good to eat — there’s no need to be in a hurry. In the first few days of Hunger Training, you will learn to eliminate unnecessary snacks and find an eating routine that works for your life and your metabolism. It’s essential to find this rhythm in the initial stages before it gets more difficult.
Before long, as you log more premeal glucose values below your current trigger, Your Personalised Trigger will ratchet down to ensure you are continually stretched and move towards your goals of fat loss and optimised blood glucose. If you do this consistently, Your Personalised Trigger will continue to drop. Don’t be in a hurry!. The degree of difficulty will ramp up soon enough to ensure you move toward your goal of optimised blood glucose and metabolic health.
We have heard many reports from people in the Data-Driven Fasting Facebook Group and challenges from people who have tried extended fasting and have lost touch with their healthy appetite signals. Although they can push through hunger, this often leaves them less able to stop eating when they have had enough food. Hence, their progress slows and often reverses, despite their deprivation.
Your body LOVES routine. While daily intermittent fasting can be useful to compress your eating window to give your metabolism and digestion time to rest, repair and use up your glucose and fat stores without continually being topped up, 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.
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 tied to not only light but also your activity and eating patterns.
Generally, it is ideal to eat most of your calories when the sun is up, and if possible, earlier in the day when your body is primed to use the energy rather than store it. But 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 other days. As you push through hunger on some days, you tell your lizard brain that food is scarce, so next time you eat, you will likely eat more than you need to in order 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.
While there is a lot of talk about autophagy (i.e. self-eating) 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 smartest fasting gurus admit that we don’t know what length of fasting is 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 maybe 14 days to get the full benefits of autophagy?
Unfortunately, studies done on yeast and worms in a Petri dish aren’t relevant to humans living in the real world who also need to be robust and resilient to survive into old age.
Valter Longo has shown that cycles of 48-hour fasting produce benefits in mice. But 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) could kill many humans.
While people often refer to Angus Barbieri, who fasted for 382 days and came out thin and healthy, they don’t talk about the ten young men in their 20s that died after not eating for between 46 and 71 days in the 1981 Irish Hunger Strike.
Autophagy is occurring to some extent all the time, particularly when we are not overfed and thus in a negative energy balance over the long term. Too much autophagy can be harmful if you are losing precious lean muscle mass when you fast and don’t get enough protein when you eat.
When we fast for extended periods, not only do we miss out on the nutrients on the days we fast, we tend to gravitate to energy-dense, nutrient-poor, low-satiety foods when we refeed. Over time, this cycle can worsen metabolic health with a loss of lean mass and nutrient deficiencies. Common symptoms of extended fasting without adequate nutrition can be loss of lean mass, hair loss, fatigue, disconnection from normal hunger signals, fatigue and lower metabolic rate, leading to weight loss plateaus.
What we do know for sure is that achieving a more optimal body composition, body fat, fasting blood glucose and waist to height are highly correlated with a reduced risk of dying of any cause.
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. Cumulative smaller bursts of autophagy followed by nutrient dense refeeding are more likely to be beneficial than occasional multi-day fasts followed by energy-dense nutrient-poor binging.
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 the trigger. (Katie)
- When the momentum of the challenge ends and the support and interaction, you can slip back. 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 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)
- I got very stuck in looking at different foods and analysing my habits for quite some time before even focussing on what to do. I knew it, the challenge was over, and I felt I had barely scratched the surface. It was the same with the Nutritional Optimisation Masterclass. (Rowena)
- 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. Also, I seem to have an easier time with DDF than I ever had with weight watchers, 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 learn how to maintain it. Maintenance is the hardest part for me. So, I will be back to progress, learn and consolidate. (Tammy)
- All of the above. (Maureen, Sue, Katie).
- Data-Driven Fasting
- Download the manual (PDF)
- Facebook Group
- QuickStart Guide
- Success stories & results
- FAQ #1 – What makes DDF different?
- FAQ #2 – Getting ready
- FAQ #3 – Tracking your progress
- FAQ #4 – WHEN to eat
- FAQ #5 – WHAT to eat
- FAQ #6 – Winning the mind game
- FAQ #7 – Understanding your unique metabolism
- FAQ #8 – Troubleshooting
- FAQ #9 – Things that affect your blood sugars (other than food)
- FAQ #10 – Moving on…
- Join the next 30-Day Challenge