Don’t eat that!

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Fasting is awesome.

Everybody can start doing it, there are a lot of health benefits and it significantly boosts focus and performance.

After reading this newsletter you have all information you need to get try out your first fast next week. Enjoy!

Background and benefits

“Fasting” was a constant part of humans’ lives until a very short time ago. Chances are that at least your grandparents experienced some periods without enough food and every generation before definitely was sometimes fighting hard to get them calories. Naturally, our bodies have mechanisms to deal with a restriction in nutrients. We can leverage those to increase our physical health and mental performance.

The potential benefits include reduced body fat, improved digestion, and overall health but more importantly for the topic of this newsletter, we can use fasting to improve our mental performance. It can give us more clarity, more focus, and make us feel awake and attentive for longer. Even when fasting for durations as short as 14 hours.

Different types of fasting

How long we fast and what we consume during a fast both make a big difference in what results to expect.

The 3 main approaches of consumption while fasting are:

  • Nothing Mostly practiced in religious contexts. No food, no water, nothing. Since water is pretty important for performance, not the most recommended variation.
  • No calories The approach that promises the best increase in performance. Making sure not to consume any calories via sweeteners you can have as much water, black coffee and tea as you like.
  • Restricted calories / foods Fasting protocols that include juices, soups, or similar low-calorie foods are mostly used for improving general well-being and health. These are valid and have their place but are not directly relevant to work or mental performance.

Now let’s look at the second important factor: duration.

Short-term fasting

The most practical and common approach to fasting is known as intermittent fasting or time restricted eating. Fasting for 16h a day, half of it in our sleep, and limiting eating to the other 8h takes more intention than effort and is something you can do every day.

Or only on work days if you are only looking for performance. Not eating from 8pm till noon the next day is a great pattern to regularly get some demanding work done in the mid to late morning.

How to get started?

Pick a day, stop eating at 8pm and only consume water, coffee and tea till noon the next day. Done.

It really is that simple for a short-term fast but here are a few more tips:

Don’t stress out about it

If anything “goes wrong” you can just eat and try again another time. No big deal.

Check-in with yourself

Note how you feel during the later stages of the fast. See hunger come and go and your focus rise.

Drink lots of water

It may make you less hungry as well but it definitely makes your stomach feel less weird.

Sprinkle some salt on it

Sometimes not eating can give you a slight headache-like feeling, especially during longer fasts. This might come from a lack of electrolytes and a pinch of sea salt in a glass of water oftentimes makes the feeling disappear in minutes.

Wait 15min

Hunger, like many feelings, does not last very long. If you are intent on finishing your fast but at the moment you feel like you just have to eat, take a breath. Wait 15 minutes. Let the feeling pass and if it doesn’t, remember, don’t stress out about it. Have some food.

Long term fasting

Once you feel comfortable without food for half a day it is worth it to experiment with longer fasts. Not eating for 36-72 hours is an interesting experience and it’s good to see that it’s not as hard as you probably thought.

This is a great tool for weight loss, write me an email if you are interested in more details.

Working out while fasting

Not only can you train without having eaten before, but it may also increase some of the benefits. There’s some evidence that endurance training in a fasted state burns more body fat and improves hormone levels.

You will have to experiment for yourself with how strength or endurance training influences your energy levels and where your sweet spot is. A high-intensity strength session may give you an additional boost in focus and energy but can also leave you drained. While optional during intermittent fasting, resistance training is crucial to prevent muscle loss when abstaining from food for more than 36h.

Bonus: fasting when getting sick

There seems to be no hard evidence for this but I still want to mention a practice many people, including me, follow. We stop eating as soon as we realize some symptoms of an infection like a scratchy throat or those certain types of headaches. The theory behind it is that digestion takes energy away from the immune response and that the increased stress response of not having food helps combat the infection.

As I said, this is more anecdotal than hard science but if you gathered some experience with fasting you might want to give it a try next time you feel an infection.

If it does not work you can go back to last week’s newsletter and try the breathing exercise for unstuffing your nose.


Fasting is one of the simplest tools to make us feel more energetic and productive.

By not eating late the day before (which your sleep schedule does not like anyways) and pushing the breakfast to after your 90min morning deep work block you give yourself the chance to experience a constant and calm focus that gets things done.

Give it a try next week, let me know how it goes!