The Fasting Experiment

In the modern world we live caged like battery hens or lab rats.

As part of this, we are protected from predators, from the weather and we are overfed with (often artificial) food. 

On balance, this beats starving in a cave during the Ice Age but it has the unfortunate side effect of making us soft.

So maybe its time to toughen up a bit?

What doesn’t kill you makes you stronger. So one way to toughen up is to lead a more natural life and experience a little more challenge.

The best challenge does not come from working ever longer hours in the office or playing Call of Duty with the difficulty setting turned up.   The best challenges come from overcoming natural challenges that our ancestors would have dealt with.

We evolved in challenging natural environments.  Imagine living as a hunter gatherer on the African Savannah or as a caveman in France during the Ice Age.  Our ancestors needed to solve problems….getting food, building a shelter, finding friends, conceiving and raising children, escaping predators.  Evolution rewards the activities and experiences that solve these problems.

So maybe we need to find ways to make life a little bit harder and experiment with making life a little bit more natural. As part of this I realised recently that I had never gone a full day without eating any food (except when ill which doesn’t really count).

This called for the 1 Day Fasting Experiment.  So I decided to try eating nothing between going to bed on Friday, skipping all food on Saturday, going to bed and then breaking my fast on Sunday morning.

I’ll say upfront that this is not about penny pinching or cost savings. Good food is one of the great joys of life and we are optimising for happiness around here.

No, the main benefit from fasting is from strengthening your willpower and your ability to defer gratification. The ability to swap instant rewards now for greater payback later is perhaps the ultimate super-power.

And its transferable from one area of your life to another. Not buying shit now and instead saving and investing your money is all about self control and the ability to defer gratification for greater rewards later.

I got up on Saturday as the sun started to rise (since busting out of the Prison Camp earlier this year, I haven’t needed an alarm clock).  I then went out mountain biking with a group of local guys.  I think of this a bit like replicating the environment of paleolithic hunting – an early morning start, a group experience, a mix of guys co-operating surrounded by beautiful countryside.

I get a lot from this.  I get to hang out with guys who do not all work in Finance or Law, who have normal lives.  I get to discover new trails and new aspects to the countryside around where I live, all part of the benefit of living a more local life.

On my return from this, my normal policy would be to reward myself for the exercise with a slap up late breakfast or brunch.  But, as this was the day of the Fasting Experiment, I replicated the experience of an unsuccessful hunt and did not eat.

Living as a hunter gatherer would have been an irregular gig with a lot of volatility in the outcomes. Sometimes you would have got lucky and caught an antelope.   Othertimes you would have struck out and gone hungry or been forced to eat like Bear Grylls when he’s scraping the bottom of the food chain.

In the brilliant book The New Evolution Diet, Arthur De Vany points out that almost every living creature through history would have gone hungry now and again. So our bodies are highly likely to be well evolved not only to cope with periods of intermittent fasting but maybe to thrive on it?

What doesn’t kill you, makes you stronger.  To use Taleb’s phrase, living creatures are anti-fragile. Antifragility is the opposite of fragility:  it means that a certain amount of disorder or variability actually strengthens you.

Volatility in your food intake is just one example of this.  It’s more natural (hence probably better for you) to experience some feast and famine rather than always have 3 regular meals a day and a daily intake of 3,000 calories.

People sometimes say that your body is like an engine…you first have to put fuel in for it to work.  But if you think about our ancestral environment, we hunted to be able to eat….we did not eat to be able to hunt.  Our bodies are infinitely more complex than an engine. They are complex systems with feedback mechanisms honed over millions of years of evolution.

It seems entirely plausible to me that fasting has non-obvious health benefits. De Vany argues that when we experience an environment of food abundance our bodies focus on cell growth.  When we experience an environment of food scarcity, signals triggered by hunger tell our cells to focus on repair rather than new growth. So periodic fasting prompts cells to fix themselves and so is a way to slow ageing and maybe avoid some cancers?

According to De Vany, during times of plentiful nutrition, the most effective way for DNA to propagate itself is through reproduction, since there is enough energy out there to support offspring. When there is no excess, DNA is best served by not reproducing….low levels of food (especially carbohydrate) signal that it is in the DNA’s interest to preserve itself through gene repair and cell maintenance.

There’s no need to email telling me that I’m not an expert in nutritional science. I already know that.  Here’s the thing: I don’t need to know the scientific detail to understand its possible that fasting could have physical benefits.  I just need to understand that evolution is a powerful process and that we are well adapted to the environmental conditions that applied throughout most of our history.

Even though it makes sense that fasting could have physiological benefits, it may be that the mental and emotional benefits of fasting are even more powerful. In a world full of convenience and excess consumption, fasting can be thought of as a spiritual practice. Fasting encourages gratitude when the fast is broken and food is appreciated so much more.

Fasting replicates a more natural world, before shopping malls, convenience food and carbohydrate based profit maximisation.  If you can get used to the idea of skipping the odd meal, you will not go to pieces when deprived of food for a few hours. You are then less likely to be a forced buyer of unhealthy convenience foods.

Fasting helps us avoid becoming like the obese jellybaby humans in Wall-E, driving around in electric chairs sucking on a sugary drink through a straw.

Fasting reminds us that our evolutionary automatic programming can be manually over-ridden. We can use our pre-frontal cortex to override the ancient reptilian parts of our brain that govern greed and the acquisition of food and other “stuff”. 

There is a link to personal finance here. It’s not a big leap from being able to go a few hours without the instant gratification of food to being able to resist spending your money on consumer nonsense.  If you can rewire your basic factory settings in this way, you will get rich over time.

When you first need to get your spending under control it can be very powerful to track every £ / € / $ spent to answer the question: where does it all go? Similarly, if you are overweight, its super-powerful to fast and then keep a food diary (either paper or via a free app like Cronometer or MyFitnessPal).

The fasting experience itself was surprisingly easy.  I continued to function just fine – throughout most of Saturday I felt sharp and alert.  I drank liquids (tea, coffee, water) which distracted from the feeling of hunger. I went to bed slightly early on the Saturday night (and I slept well) so that the fasting would go on whilst asleep – no willpower required.

Waking up on Sunday morning, I felt good and no hungrier than any other day.  Like many things in life, the anticipation of fasting for a full day was much scarier than the actual experience.  This is why we should spend more time experimenting.

After my day of “deprivation”, normal service was resumed this morning when I ate like a King, feasting on food delivered direct to my doorstep by the modern economy. If you think about it, this is the height of luxury. 

Gratitude is a powerful tool for greater happiness.

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  1. I’m quite partial to ‘enjoying the feeling of hunger’ sometimes, though i’ve never gone a full 24 hours without. I fully agree that we have it too good and a little suffering is good for the soul (as well as the body too) now and again. Feeling hungry is kind of nice occasionally and balances out those times when you’re uncomfortably full after a big meal.

    This ‘suffering’ element, and the weird enjoyment aspect to it is probably what draws me to activities like cycling….no matter how hard I train it never gets any easier, I just go faster.

    As for combining the two by fasting for 24 hrs after cycling, that’s something I could never do. When I ride I turn into a calorie consuming machine of epic proportions 😉

    1. “Kind of nice”? Is that phrase not an Americanism!? Quelle horrreur! If you do that again, The Escape Artist will be forced to call the O.E.D. Special Enforcement Branch;-)

      1. lol!
        i think “neat” instead of “nice” would have warranted such measures!

  2. Hi TEA, I’ve been using intermittent fasting for weight control and the health benefits for over 2 years now so it was very interesting to read your take on it.

    Most Mondays I don’t eat until late evening when I will just have some home made soup. If nothing else it seems to re-set my body following what can be sometimes be an over-indulgent weekend and, having read the science, I’m fairly convinced it is doing me some good.

    I’ve never tried combining no food with vigorous exercise although fasting never leaves me feeling tired or lethargic – if anything I feel “sparkier” – so perhaps I should give it a go. As you say our bodies are designed to expect (and need) a challenge now and then.

    1. Exactly…”sparkier” is the perfect description

  3. but what was it like? how did the day go? how did you feel? did you drink? could you sleep sat night? how did you feel sunday morning? there seems to be a fair chunk of this story missing..

    1. Thanks for the comment….I’ve just added answers to those questions into the post.

  4. Hi TEA,

    I love a challenge, especially an ‘old school’* stoic test like fasting.

    I like the concept of being comfortable with being uncomfortable. When you’re able to not only endure, but enjoy or relish a challenge like this, it makes you a different human being to most. Most people seek convenience but I find there’s something particularly satisfying about testing myself in this way. I ditched my car permanently in April, and although I don’t have a long commute, I like the feeling of biking home when it’s pissing down with rain, dark and the wind is blowing. The feeling when I get home is fantastic. I don’t think people driving home experience that.

    I haven’t tried fasting for a day since I was a teenager, but it’s something I must try again soon.


    *Does that violate O.E.D. Special Enforcement Branch?

    1. that’s just about OK…but if you’d written “old skool”, you could have been in real trouble

  5. I’ve never tried fasting before (does not eating for 18 hours because you’re stuck in an airport with no money for food count?) but it’s something that interests me. I might give it a try to see how it goes. I’m the sort of person who can be distracted enough to forget about eating so I don’t think I’ll find it too difficult, just not sure how I’ll feel!

    I can’t do the vigorous exercise + no food, not since I tried a couple of times when I was a teenager (early morning physical education on an empty stomach) and nearly passed out on both occasions – not sure what happened but teacher seemed to think it was because I have pretty low blood pressure.

    Anyway, I’ll give it a go one weekend, when I don’t need to drive anywhere in case I get affected aversely (and my stomach is growling too loudly!)

  6. Hey,

    Found my way here through a link on Monevator.

    Your comment about heading out riding to speak to some normal people, outside of Finance or Law rings true.

    Never tried fasting, like Under The Money Tree I am a calorie machine. Did you honestly not feel knackered at all?

    Awesome blog by the way. Good to see writing about taking FI into your own hands and not blaming the government or someone else for your position!

    Mr Z

    1. Mr Zombie

      Welcome to the site!…I recommend this post for you.


      1. Haha. Yes, the bastards are everywhere at work! I’m working on my cure to freedom right now.

        Mr Z

  7. If you can get used to the idea of skipping the odd meal, you will not go to pieces when deprived of chicken nuggets and chips for more than 3 hours.” – Classic! 🙂

    Fasting is not something I have tried although would be up for the crack. It is a slight worry as I am a calorie burning machine as well though.

    I am pretty sure if I were born 5,000 years ago I would be slightly more than the walking dead right now* whereas those people who say they are jealous of my ability to be able to eat what I want and not gain weight would have lot’s more energy stored up for the leaner periods and would be the ones to survive. Of course there is a small chance that I am just far more active than they are and so my calories in/out equation is much more balanced… barring a double blind medical trial we will never know 😉

    This post is another reminder that I need to watch Wall-E!!!

    *i.e. actually dead

  8. Hi TEA

    Very interesting and thought provoking.

    I hadn’t thought of fasting for a whole day, but I do think there could be something to the possibility that our ancient “core” can benefit from the break from food.

    I will have to look into this some more, not only do you get the potential health benefits, but also save cash which you can use to invest.

    Best Wishes
    FI UK

    1. Thanks….I didn’t do it to save money, although that is a side effect. I did it to become less of a wuss.

  9. Interesting stuff. I’ve never tried a full day fast and while I’m still working I’m reluctant to “spoil” a valuable weekend day by trying it out – though based on your experience it wouldn’t be as bad as I expected, and if I did it on Saturday I’d have the Sunday to do nothing but eat if I so desired. Would it be cheating to pig out on the Friday night before a Saturday fast?

    The closest I get to this at the moment is that for the last few months I’ve been forcing myself to get up in time to eat breakfast before work (I am *not* a morning person), then I just have a few pieces of fruit at my desk during the day and a big meal in the evening back at home. This was primarily motivated by a desire to save the £5/day I was spending on takeout food, but I find it surprisingly un-unpleasant in general. Not having to go out and queue up to spend the £5 is a pleasant side-effect as well.

    (Even if this pseudo-partial-fasting is good for me, I’m probably killing myself with the heavy fructose intake from all that fruit. 🙂 )

    1. No, it wouldn’t be cheating to pig out the night before…replicating a bit of feast and famine is the point. And i dont think a bit of fruit is a problem either…thanks for the comment.

  10. Is this paleo stuff backed up by any actual research? Evolution is great and all, but has evolution really had any time to select for traits that help you live to be 100? It seems to me that we are well evolved to live between about ages 5 and 60, where with modern medicine you will have very few problems regardless of your lifestyle. IMO.

    1. Yes, there is a lot of research that supports the paleo diet….see the Bibliography in the book (page 209 in my copy) which is full of academic studies. Or better still, try it yourself and see whether it works for you.

  11. I’ve found that a combination of intermittent fasting and paleo like approach to diet has dramatically changed my health and energy levels. I used to be the one catching every bug going in the office and my wife and kids would look knowingly and mutter “low blood sugar” at times during the day.

    Since going paleo five years ago (not really paleo but it’s an easy marker – I actually started out following the ideas at I’ve had one day off sick and I can miss a meal without any trouble at all.

    Last year I added in Body by Science training – I now look better than I ever have too.

    Eating along ancestral lines, training along ancestral lines – made such a difference in my life.

  12. Yes, someone besides me gets it that Wall-E was a documentary! A sad & scary one at that!

    1. Thanks Patty – if you liked the Wall-E reference then check out Get Rich…by Watching Films.

  13. I’ve just gone 24 hours without eating, but it was from midday-midday, not midnight-midnight/waking-waking. It was so easy I have to wonder – is this cheating, or is it equally valid to do it this way?

    1. Maybe it is cheating. You can’t eat in your sleep, so ‘not eating from waking Mon morning until waking Tue morning’ is really something like a 32 hour fast, as you didn’t eat during the 8 hours you were asleep Sunday night/Monday morning.

  14. Richard · · Reply

    I’m a big fan of fasting, though I’ve given up on the one or two day fasts now and prefer longer periods of no food or very restricted calorie intake. As a non-obese (it has to be said, otherwise I trigger the Internet trolls) type 2 diabetic, I switch to a low carb diet. Later I read a study (this was about five years ago but the NHS seems to have just caught on to the same study) about restricting calories to 600 per day for 8 weeks curing or reversing T2, so I tried it. I was shocked that on day one I was a little hungry for an hour or so but for the rest of the eight weeks I was not hungry at all. Instead, I was filled with energy I’d never had since being a small child and improved mental clarity. I really recommend fasting, though many people disregard it, probably because it doesn’t fit with the idea of losing their treats.

    1. DaveTMG · · Reply

      The high energy levels sound like you are in ketosis, where your body is burning fat instead of glucose.

      There is evidence to suggest that it is a state in which a lot of body repair happens.

  15. […] in 2014 I posted Get Rich…Fast in which I wrote about the benefits of […]

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