Let me introduce you to the daringly promised magic pill for fat loss, muscle growth and even longevity. The past year’s new kid on the block of the nutritional trends. Getting this diet public was one of mankind’s greatest recent achievements. Right behind getting Donald Trump elected as POTUS1 and inventing the pet rock.
Just kidding. Right now your bullshit alarm should go wild. Although most of the previous points may not be entirely true, I am a big fan of intermittent fasting, and it can benefit you! There might be many shady promises around, likewise many nutritional and fitness topics, but there are also solid claims out there build on a foundation of evidence, scientific-objective one as well as anecdotic-subjective one. Overall it is a great thing to try and consistent with what our ancestors definitely encountered throughout their daily lives. Contrary to today’s grocery culture, food wasn’t around all the time and came in waves, after a successful hunt plenty was around, maybe in Winter not so much. And that’s what we’re trying to replicate – we’re building the perfect human zoo environment.
Let us therefore dive into the vast realms and talk about the question of what is intermittent fasting, the health benefits of intermittent fasting and explore the most common schedules, and last but not least see how you can easily start with some kind of fasting – right now! Sound interesting, right? Let’s get going!
Many think of intermittent fasting in terms of another diet. Nothing could be farther from the truth! It is not another diet, rather a way of timing your meals. It is a way to incorporate times of feeding with times of fasting on a daily basis. Why is it constructed that way?
While fasting your body’s metabolism undergoes significant changes that are linked to many benefits. We’ll go into those later on. It is constructed that way so that people can reap the health benefits of intermittent fasting and have a handy tool at hand: For most fasting for an extended period of time is nothing they can integrate quite often – I found day for example alternate day fasts, where you skip eating for a day or two a week very taxing combined with loads of calisthenics. My performance tanked. With intermittent fasting on the other hand you get to eat every day – and by throwing a dayfast in on off-days I don’t run into the danger of eating too little or getting overstressed.
Intermittent Fasting is a tool that should make fasting accessible on a daily basis for everyone, except those with grave health conditions. A great book on this is ‘Intuitive Fasting*’ by Dr. Will Cole – he tries to make the mindset behind fasting accessible for everyone. That’s what its about and should let anyone tap into the health benefits of intermittent fasting without the need to restrain from food for days on end. It’s a little fasting on a daily basis.
Time-Restricted Eating, not another Diet
That’s why all these kinds of fasts are also referred to as time-restricted eating. Common intermittent fasting schedules would be the 16-8 one, the TMAD, OMAD schedule. We’re going to talk later about those, too! What all those have in common is a daily window of feeding, the difference is the number of meals and window of feeding time.
In contrast to other methods of fasting like the alternate day fasts, multiday fasts, or extended waterfasts – those span at least 24h sometimes 2-3 days or even more. Those are often done sparingly throughout the year and were for a long time tied to religious practices. But there are also many examples of intermittent fasting schedules that were used throughout history – think about the Christian fasting period after Easter or the Muslim Ramadan, The main difference is that those longer fasts can only be done a few times a year – if you want to do so healthwise and will impact our athletic performance for example. A three-day fast is no time for PRs.
But as you see now – I haven’t noticed once the choice of food. Because intermittent fasting in itself doesn’t care about what you eat – it’s all about timing and planning, rather than the What of nutrition. Fasting is not another diet.
It is not another new diet (that sucks)
Diets suck. Let’s face it. In m opinion, our whole medical and nutritional paradigm is flawed, even broken. Around 1 in 200 diets succeeds long-term. Wow. Great. Not really. That’s because all this dieting got it backwards. We try so hard to lose weight and forget that weight loss is rather the consequence than the goal. The goal is health!
Get healthy, metabolically healthy, and weight loss will follow. Therefore health is a qualitative approach and eating healthy involves a lot of education in our civilized western world full of temptations and unnatural food choices. But diets just want you to ‘eat less and move more’. A purely quantitative approach. Or even worse, they want you to buy all those brain-dead magazines and go each month on a 3-day tomato diet to lose 10lb in 3 days. Shit is broken. A great book addressing the question of quality from a very uncommon point of view – one that woke me up quite roughly – is Dr. Paul Saladino’s ‘Carnivore Code*‘. Albeit the name it does contain a lot more knowledge than ‘eat meat solely’. Highly Recommended Read!
Quality will get you towards health and improve your quantity along the way. Intermittent fasting is one of those tools that helps you improve both:
Quality by helping us rebuild an environment our ancestors lived in, facing the issue of not eating on a regular basis to tap into deep metabolic changes
Quantity by cutting your eating window short – most importantly to not eat at night, because we’re creatures of the day, not nocturnal2
7 enormous Health Benefits of Intermittent Fasting
Alright, let’s get down into the weeds. I always like those scientific fact parts the most, and I hope you can relate! Any ways. There are many claimed health benefits of intermittent fasting, but the 7 down below are the most established ones. If you want to dive deeper into each topic, feel free to follow the links to the science and more in-depth work.
Autophagy is the process of cleaning up within your cells. It gets often switched up with Apoptosis – so let’s first get those two guys right:
Apoptosis is the programmed death of a cell for many reasons. Important to note here is that it’s a process that emerges from the cell, in contrast to necrosis, which is an unwanted cell’s demise. Apoptosis is tightly regulated, and a process once set into action unstoppable. A cell can undergo this suicidal process through internal changes or external signals. As a fun fact aside – 50-70 billion cells undergo this process within your body per day.
Autophagy, on the other hand, is a natural process that removes not functioning or excess components within your cell and is triggered by stress. Kind of like a spring clean-up. This process is there to maintain homeostasis within your cells – to keep everything in a balance. All the excess garbage gets thrown into the autophagosome – a cellular compartment full of enzymes. You can imagine it like a wood shredder – literally. Every substance thrown into it gets cut down into pieces molecularly.
Coming back to fasting, it is true that fasting enhances autophagy at different rates because fasting is a strong stressor for our body. So do many other things, a big one is exercise. Generally the longer the fast the higher the impact on the rates of autophagy. Most sources tell that autophagy starts to rise after 24+ hours of fasting and peaks around 36 hours before staying on that level. I think it’s a highly individual process and depends very much on your metabolic health so that you can also reap benefits, maybe not of that increased rates, but of consistent daily changes throughout a fast of 16 or 18 hours a day. But if you want to reap the benefits of these higher levels, a common practice is to throw in a few multiday fasts every 3-4 months.
Make the Metabolic Switch
Your body can run off fats, carbs, and to a small amount of protein that needs to be converted to carbohydrates. But it is true to say that our two main sources of fuel are either fatty acids or glucose. Plus, there is strong evidence that you should run either on fat or carbs for optimal function at a time. Awhile being able to comfortably switch from burning carbs to a pure ketogenic state is of tremendous importance. This transition is called making the metabolic switch – from carbs to ketones and fatty acids.
The problem is that nowadays in our sugar-fueled society very few know how to run on fatty acids alone, not even to mention ketones.3 Often when people don’t get food on time they get hangry – blood glucose is unstable and drops. The body wants more and uses emotional capacities to hit the message home. The result is a raging girlfriend going totally mayhem because you fucking waste of genetic material served dinner late or forgot to pack the cookies for your trip.
Intermittent Fasting and longer fasts will inevitably push you into ketosis and fat-fueled states. On average your carbs are depleted after 12-16 hours if you’re active or work out even shorter.4 This daily forces ketosis will teach your body quickly to do the switch from carbs to fats without changing your diet. If you’d know even change one meal a day to a keto meal you’d stay in ketosis even longer – but that’s for another post. That said neither permanent ketosis is the goal, nor permanent carb-burning. It’s a balance and depends on the season and your daily endeavours.
Improve your Insulin Sensitivity
Insulin sensitivity is a complex rabbit hole to get into! Some resistance is wanted and physiological for example – like your adipocytes after they’ve taken up enough energy. This is a satiety feedback mechanism. Others are pathological and often occur with metabolic syndrome and diabetes. The full-fledged problem then is called insulin resistance – it is when your cells receptors get resistant to normal levels of insulin and need more to get the same job done.
One great tool to better insulin resistance and therefore also overall insulin sensitivity is intermittent fasting.5 The problem with the prior is high levels of blood glucose and insulin all the time. Your body gets used to it simply stated. Intermittent fasting by definition introduces times of very low, fasted blood glucose. Throughout this time very little insulin and glucose should be in your bloodstream. This is a good thing, for your cells to not get resistant. Of course, it’s only one part of the puzzle. There is a lot of nuance to this discussion than purely demonizing glucose! Another big part is changing habits and the quality of nutrition. This goes for sick individuals, as for healthy ones alike. Healthy folks also get into the benefits of low blood glucose levels and expose their body to a more natural variety of circumstances than high blood glucose all day every day, thanks to doughnuts and Twinkies. Check out Jason Fung’s book ‘Obesity Code*‘ for more information.
Fasting Time = Get Shit Done
Fasting is a stress-inducing activity. Fasting naturally raises the stress hormones like adrenaline and cortisol within your body.6 Your body wants to be active, give you the energy to make you forage for food and eventually eat. That said fasting can be a problem for chronically overstressed, overtrained individuals. For others, this stress is a great tool for increased activity.
Many people feel like they get a lot done when fasted, some like me even like training fasted. This is all tied to those stress hormones that make you active. Plus, growth hormone also gets secreted when fasted.7 This whole cocktail of hormonal changes is beneficial for getting shit done, training and simply having a clear mind while doing so, not torn down by your intestines working hard and drawing blood into them.
Your Gut gets a Rest
One topic that is talked about a lot recently is gut health and microbiome. Righteously so! In my opinion gut health is very important and most chronic disease starts in the gut, or more specifically with what you put in there. What you eat is what you will be. There is a huge amount of life going on in yourself, and it is in a constant flux of giving and taking.
Without the microbes in your gut, you couldn’t use many contents of your foods, one example of that is short-chained fatty acids such as butyrate. By fasting your gut gets a break. A break mechanically by not stuffing more in there, but also lifecycle-wise. What do I mean by that?
By not eating you kill microbes within your gut that otherwise flourish in the presence of foods. Often those tend to be the gram-negative, aka non-beneficial ones – and we clearly know that observing the microbiome of people that participate in Ramadan.8 If you want so, intermittent fasting can be a kind of daily natural gut cleanse. Plus, the mechanical stop of foods will give the inner lining of your intestines, also called the mucus layer, the chance to replenish. In leaky gut for example this layer gets extremely thin and makes the transport in and out of your cells too simple. Many foods containing antinutrients like lectins or tannins damage the gut lining and microbiome. Those foods are for example grains, legumes, and nightshades. Not eating gives your body time to catch up – even better though would be to avoid those completely!9
Distinguish Hunger from Appetite
People nowadays think they need food to function – a pre-workout meal here to fuel your workout, a bit of candy to think better, and breakfast to have enough energy for the day. Unfortunately, all of those claims are wrong. You don’t need energy that frequently and once well fat-adapted even a fasted workout shouldn’t have a huge impact on your overall performance. For me, basic handstand sessions even feel better without food in the stomach.
What intermittent fasting can teach you, the hard way, is to distinguish appetite from sincere hunger. Plus, it shows you that there is absolutely no need to eat that frequently – it’s rather counter everything we humans are metabolically and unless you are competing in a specific sport like bodybuilding or need a ton of calories like a strongman, it’s pretty much useless.
The interesting thing is that your appetite will adjust after 1-2 weeks to the times you eat – this is a hormonal response of ghrelin that is simply anticipating food at certain times and throws on the eating machinery upfront. When fasted then you’ll often not think about eating or feel hungry. Even on longer fasts appetite often seizes, unless you really hit a workout while doing so. Just think about it – at your belly are a lot of calories stored and readily available to be burned. We humans are great at starving. Hunting helped us evolve towards that trend – after a big kill we had plenty to eat, but when the next kill was hunt down wasn’t sure, so we became well adapted to overeating and periods of starvation.
Simplicity planning Meals
Fasting by definition removes meals – sometimes breakfast, other times dinner, or even more if you’re going for the OMAD approach. The need to only prepare one to two good and big meals a day gives you a lot more freedom and time. I seldom spend more than 2h per week preparing all I eat. Mealprep combined with intermittent fasting can free up a lot of your time that you can use towards other things such as working on your passion, training, or caring for your meaningful connections.
This simplicity is definitely one of my favorite benefits – because it is immediate and quickly to grasp. Plus, you are flexible. If you want to eat breakfast a day go for it, you can skip dinner that day. Or just screw it if it is one day – no need to stress yourself about one sole day. It is about what you do 90% of the time and if you miss your fasting window at one day that won’t do any harm.
What changes within my Body when I Fast?
Switch from Carbs to Fatty Acids & Ketones
Probably the biggest change is the metabolic switch from carbohydrates to fatty acids and ketones that will occur once your muscle and liver glycogen stores are depleted. Then most of your body burns an increased amount of fatty acids from your storage. Additionally, your liver, the working house of your body, starts to make ketones from scratch – the most abundant is Beta-Hydroxybutyrate or BHB. Why does it do that? Certain tissues need glucose specifically like your testicles’ Leydig cells or the neurons of your brain. With no glucose available they switch to ketones because fatty acids can’t get into the brain thanks to the genial structure that is the blood-brain-barrier.
This switch normally occurs during sleep, fasting, or when eating a ketogenic diet and has a whole array of metabolic changes10:
Altered Insulin Sensitivity because of low blood-glucose levels, manipulated receptors, and low overall insulin
More mitochondrial cofactors such as Acetyl Co-A, NADH, and FADH that turn on longevity genes
BHB alters Gene expression, acts on DNA molecules and cell membrane transporters
Plus many more!
That said, it is still a lot of unclarity about ketones but those mechanisms are clearly understood. Ketones are impressive and this whole metabolic array of changes seems to be very beneficial – not all the time, but to tap regularly into. Plus, learning to run on fat, to be fat-adapted will teach you a lot about metabolic flexibility and help you to not be a hangry person if food arrives a bit later on your plate a given evening.
Rest for your Gut & Microbiome
By definition, while intermittent fasting no food will enter your intestine for a while and your gut will get a break. This break provides many benefits to your gut and specifically its microbiome. One study found that fasting manipulate the microbiome and gets the bad bugs out. This has effects on the short-chain fatty acid production within your intestines and seems to be very beneficial on the thickness of your mucus layer, as well as the permeability of your gut.
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Easily said, intermittent fasting seems to be a daily gut cleanse, longer fasts even more so. Get rid of bad bugs and promote the growth of better ones by feeding them and yourself well.
Your Stress Hormone levels rise
Fasting is a stressor for your body. This can be good or bad depending on – you. If you’re already overtrained, overworked, underslept, and totally pissed off on a given day fasting might be too much. But generally if you manage your stress well it can be a beneficial habit that might even help you manage time, increase flexibility and therefore indirectly decrease stress.
When fasted your body’s stress hormone levels increase – namely adrenalin, noradrenalin, and cortisol. Sympathetic activity therefore increases – some scientists found this out directly by measuring subjects’ HRV. Why is that so? Cortisol first and foremost releases fatty acids from your storages and gets them into the bloodstream for energy. Moreover, mixed with the other two they provide energy for you, damp hunger, increase alertness, and stress. Simply said, your body wants you to get moving and forage for food. This effect is what makes you feel awake and productive – a great feeling in our modern hunger for productivity. I really like to get work done while fasted, write posts, and think when the head is clear.
Growth Hormone increases
Growth Hormone is an awesome substance – so awesome that many athletes take it. But that comes for a price. Optimizing your growth hormone levels naturally not. One health benefit of intermittent fasting is such.
Growth hormone is linked to a couple of effect, some anti-ageing:
Those get even more interesting in front of the point that growth hormone tends to decrease as we age. Intermittent fasts of up to 24h seemed to improve growth hormone by ~200%. The longer the fast the more growth hormone – a 40-day fast increased growth hormone by 1.200%. But there is always a trade-off, right? What’s 1.200% of GH worth on its own? Going into the sauna can manage this huge growth hormone spike, too.
Nonetheless, this growth hormone effect is one of why many people report bettering of their skin conditions, me included. And it comes for free for not eating for a while without the risks associated with injecting human growth hormone.
16-8 is the most common intermittent fasting schedule nowadays. 16-8 simply refers to the timeframe of fasting and eating: 16 hours of fasting followed by an 8-hour feeding window. Whenever this is, is up to you. Some like to skip breakfast and eat from Noon-8pm. Others like to skip dinner and eat from 9am-5pm.
16-8 fasting is so common because it is simple – it is easily accessible and can be done every day, each day. Nothing fancy needed, no additional planning, just a period of 1-2 weeks to adjust to the new schedule of eating, and you’re good to go. That’s why I think the 16-8 schedule is the one to go for most people – most importantly, it gets people off the very bad habit of eating at odd hours and night that can wreak metabolic havoc onto your system. Moreover, you’ll tap into the health benefits of intermittent fasting regularity, not in its extremes, but daily and reliably.
TMAD – Two Meals a Day
TMAD or often also referred to as the 18-6 schedule compresses your feeding window a bit further. It leaves you with 18 hours of fasting followed by a 6-hour feeding period. Why do people go for the additional 2 hours? Mostly to optimize fasting benefits, or simply because it fits their life better to solely eat from Noon-6pm or 8am-2pm.
Intermittent fasting needs to fit your life and give you more flexibility within your daily schedule. If 6 hours of eating does the trick – go for it. For me, it didn’t work as my portions simply got huge and this feeling of fullness impacted my training. If it works for you, great!
OMAD – One Meal a Day
OMAD takes it even further and leaves people with a daily feeding window of roughly 2 hours while fasting for 22. This leaves you with one meal a day. The health benefits of intermittent fasting you can tap into will be bigger, but the question is always to what degree? I’d rather choose an OMAD schedule if it helps your schedule and fits your lifestyle.
The need to solely prepare one big meal a day – often in the early evening is a big plus of OMAD. A big negative on the other hand could be the size of it. I tried OMAD and couldn’t keep up with my calories. If you don’t need to eat that much OMAD might be worth a try presuming you already gathered a bit of experience with intermittent fasting.
How you can easily start with Intermittent Fasting
Now to the most important part – how can you set this bulk of knowledge into action and start with intermittent fasting within your life? Let’s have a look at that before we wrap up!
16-8 normally is a great starting point, but even that might seem intimidating at first. Start simple is my piece of advice and remove damaging habits first – how do we do that?
The worst thing to do for a human being is to eat when the sun is down – we are not nocturnal. This will have a huge metabolic impact, for worse. Therefore start with 14-10 schedule:
Only eat from roughly 8 am-6 pm
Only eat when the sun is out
With no late-night snacking you already tackled a big obstacle. If that works I’d suggest jumping in and going for the 16-8 period by skipping either breakfast or dinner. Most do best with the breakfast approach and be productive in the morning. Try that out first, but also give the dinner approach a try. I really enjoy going to bed not feeling full.
Give yourself 1-2 Weeks to adjust
The first week of fasting will be a bit of a struggle as your body’s hormones need to adjust to that new schedule, but your satiety should adjust pretty quickly. Within these first weeks be zealously about intermittent fasting and don’t allow any meals out of your window as this will further complicate the adjustment for your body.
Even more important is to not diet. Keep calories up and don’t get into a period of starvation. This will only make it tougher and make you feel miserable, A handy tool to avoid getting into dieting without noticing is tracking your macros for that timeframe to make sure you roughly consume the same as you did as you still ate dinner o breakfast.
Drink a lot of Water
Drinking a lot will definitely help to keep your stomach full, not rumbling around like mad. A tool I used to great success is to add ~5g of salt to my water – this helped me stay hydrated, get enough electrolytes, and eliminated appetite naturally for me. Many people also like to consume tea or coffee that further dampens the feeling of appetite. If you’re into that you can give that a try, just make sure not to abuse coffee for the sake of avoiding this feeling.
Being productive uses the stress response elicited by fasting optimally. Furthermore, by being active you don’t worry about food and get shit done. Actually, this is my main hack to not feel hunger or dream about food, even on longer fasts.
It simply feels good to work fasted or even while in ketosis – there is a feeling of non-foggy headspace attached to it. Especially tasks that require creativity or a huge amount of thinking are the ones I tackle while fasted. This could be something like designing on this site, writing a post, or writing programs for clients. All of those require headspace and a huge amount of high-level thinking. Give it a try and save the more strenuous, repetitive ‘work-work‘ for later on in the day!
We’ve covered a lot of ground – methodically, metabolically, scientifically. Simply a fuckton of ground. Mostly we talked about the health benefits of intermittent fasting. Nonetheless, there are downsides, too. And without those, this post wouldn’t be well-rounded and an incomplete representation of truth. There is nuance to every proper topic, right? And often considering the cons, not-to-do’s, and that’d-be-fuckin-stupid’s helps as much as considering the obvious pros and gains. This article by CarnivoreAurelius does a good job in diving into the downsides – although I’m not convinced and think differently on a few points.
A few downsides worth mentioning are:
Lower Levels of Thyroid Hormones, as your body drives down its metabolism to preserve energy
Increased Stress that might impede reproductive hormones and our immune system
In my opinion, all of those are true, but it’s always a question of – to what extent? And fasting can be a lot of things – one fasts for 16 hours, another one for 3 days. That’s a whole different beast. Plus, it is very individual, too. If you’re already bathed in stress hormones, fasting might be the drop that spills over the imaginary bucket. But that’s a matter of poor stress management, not fasting in itself. And that’s why I’m saying I’m not convinced. Nonetheless, it is a great article listing the possible negative impacts if fasting is done wrong.
I think fasting is an evolutionary consistent approach to health and our enormously good adaption to fasting shows it. Our ancestors did fast, and so should we. It is one part of the human experience and probably why so many cultures and religions valued it or even used fasting as health interventions.
Thanks for staying down here with me – for more information on ancestral health check out my free ebook ‘Pillars of Health‘! Live ancestral and stay health my friend,
as the Simpsons have rightly foreseen 10 years ago…
Ketone bodies are a substance our liver build up, when no glucose is available in the bloodstream. Ketones are the replacement fuel especially for your brain, testicles, and muscles as those are more dependent on glucose. Plus, ketones are the namegivers of the keto diet – because solely running on fats will push you eventually into ketosis.
Glycogen storages are different from person to person keep in mind that that number is a rough estimate. Most people store 300-500g of glycogen within their liver and muscles. Trained individuals more than untrained ones – because of more muscle.