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I Stopped Eating for 72 Hours and This Is What Happened

My experience with a 3 day fast: the good, the bad and the improvable

Photo by Simon Migaj on Unsplash

Over almost 3 years ago I started my fasting journey by doing a 16 hour daily fast. This meant that I would have dinner, then skip breakfast, and have a late lunch. Not eating breakfast was super easy for me, and as I continued to research about the benefits of fasting, I decided to extend my fast to 20h per day (check this article). The reasons I got hooked up on fasting are numerous: It promotes health, I can stick easily to my optimal weight and I gain time and productivity throughout the day. There are many different fasting regimes and different benefits are associated with each one of them. More extended fasts (48hours and above) expose our body cells to stress which triggers the process of autophagy. This process consists of the ability of cells to remove unnecessary or dysfunctional components.

In the last years' research showed that autophagy contributes to longevity which made fasting go mainstream. There is a lot of work being done recently to understand how different fasting protocols affect autophagy, but generally speaking, scientists agree that longer fasts are the best to target this mechanism and promote the longevity genes. But as pointed out by Peter Attia (health and longevity expert) we know how potent fasting can be, but we still don’t know what is the optimal dosage of it. This is why, in early July 2019, I decided that over the next 12 months period, I would self-experiment and do a 3 day fast every three months. I did my first one in July, and it was not easy. Motivated by the Pre Thanksgiving “Fast Before the Feast” initiated by the Zero Fasting App, I just completed my second 72 hours fast and here is how it went.

Why I did this:

  • For the health benefits

  • To get out of my comfort zone

  • As a mental strengthening exercise

Getting ready

As I mentioned, I fast between 18 and 20 hours per day on average. I think it is very important that you’re used to some form of fasting before you start any fast longer than 24h since your body needs to be used to restricted time eating and manage to cope with the hunger. Before the fast, I tried to make my meals extra healthy and to eat a little bit fewer carbs. On top of that one week before the fast, I started with Magnesium supplementation (read here why) to make sure I wasn’t going to be deficient during the fast.

Now, let’s get into the interesting parts

The Fast

As I was mainly fasting for metabolic health I decided to include black coffee, tea, and bouillon cubes to my fast.

First day

I started fasting on a Saturday night at 8:30 pm. The first day was not really different from any other day of time-restricted eating. As always I trained in the morning but I noticed more hunger than usual. It was almost as if knowing that I wasn’t going to eat for 72 hours was making me more hungry than I would normally be. The rest of the day went perfectly fine, and the real hunger started 20 hours into the fast. At this moment, the hard part is making your body understand that this hunger is not going to be fixed with food anytime soon. To overcome it I took a bouillon cube (also important for the Sodium intake during periods of fasting) and I drank herbal infusions. I really found that having a lot of fluids and staying hydrated made hunger easier to bear. It was hard to fall asleep, but then the night was restful.

How my table looked like for three days…!

Second day

The second day I woke up not feeling hungry at all. But I had a headache and felt dizzy after one hour. I started the day with a coffee and Magnesium. But the headache was not going away so I took a bouillon cube to get some sodium as the lack of electrolytes in the body can often cause dizziness during a fast. I felt better within a few minutes. During the rest of the day, the hunger was manageable and the productivity was acceptable: I am not going to pretend that I felt awesome during the whole day, but you can get stuff done. The appreciable thing was that it was easier for me to fall asleep that day, maybe because I was more tired than usual, and the night was also good. I supplemented again with Magnesium before going to sleep.

Third day

On the third day, I had an important meeting in the morning. I had to wake up early and it was really challenging to find energy. Again I had a headache and took another bouillon cube. Fortunately, around 9 am I started to feel very good and my energy levels were on point, even better than on the second day. I wasn’t hungry for a good part of the day. Then around 4 pm, my energy started to drop significantly. Climbing stairs, for example, felt weird — my legs were very weak as if I didn’t have strength. With a few hours left to fast, I already started imagining myself eating again and that was what kept me going…

Almost finished…!

Then came the time to break the fast.

Breaking the fast

After 72 hours without food, it was time to eat! It may sound counter-intuitive, but for me, this part is when the actual challenge began. I am pretty good at dealing with hunger, but when I start to eat, I am really bad at controlling myself. I knew that after not having eaten for 3 days I had to reintroduce food slowly so as to not shock my body. I started with some berries, fruits and a few veggies. The first pieces of food tasted like the best thing I have ever eaten and the sensations were multiple times better than with a regular meal. An hour later, after I had eaten only some fruits, my body was begging me for some real food, so I listened to it and I had a full meal.

Benefits of the fast

What I really liked about this experience is that it gave me time to reflect on many things. When you cut food out of your life for a few days, the first thing that becomes obvious is how lucky you are. This may sound cliché, but when you’re hungry for a longer period of time it becomes very clear to you of what hunger really is. For me, this three-day fasting represented a moment of self-inflicted adversity that made me grateful far beyond the end of the fast. It is also an excellent tool to get you out of your comfort zone and make you test your mental strength because you will need some!

Another thing that I realized is that our bodies are actually much stronger and much resilient than we think. If at some point you feel like you’re super weak and having zero energy, think again because chances are that your body can deal with much more. I also understood that hunger comes in waves. Most of the time when you’re hungry and you want to overcome the hunger just wait and let the wave pass. You will see that hunger can disappear without food.

Meditation has gained a lot of traction these days, and that’s a great practice to find peace of mind. I found that during an extended period of fasting, the experience of meditation is even more powerful, and my mental clarity was also very good.

This fast was better than the first one, but some things could still be improved.

What could be improved

It’s been more than a week that I completed the fast, and I can now draw my conclusion on what needs improvement for the next time.

First, I noticed that my hunger increased substantially after the fast. I had the feeling that no amount of food was enough. It needed almost a week for my appetite to get back to normal. This made me understand that for 48h+ fasting, it would really be better for me to create a full fasting protocol composed of:

  • Before the fast

  • During the fast

  • After the fast

Without a proper fasting protocol, people with a tendency to overeat, like me, and that can consume substantial amounts of food, can really go overboard after the fast is ended and struggle to get back in track. So for my next 3 day fast, I will follow a method described by Peter Attia. It consists of including a Ketogenic diet before and after your fast for a period that is equivalent to the fasting period (i.e. 3 day fast: Ketogenic diet 3 days before and 3 days after the fast, also called the Keto Sandwich!). The reason for this is that starting your fast while you’re already in Ketosis is likely to help you with some of the side-effects. The other undesirable side effects that I experienced during this fast are unusual dark circles, yellowish skin color and a swollen face for a few days. I don’t know if it was linked to the fast or if it was just because of a general lack of energy caused by something else. I will try to learn more about that during the next fast.

Next steps

Overall I am more than happy with this experiment. It was far from being a perfect period, but definitely an intense one. In adversity, you create deep connections between your mind and your body, and you learn to be extremely grateful for the simple things you have. The side effects are part of the game of self-experimentation and of the pursuit of self-knowledge. Thanks to this experience, I’ve learned more about myself and about what I can do to make my next 3 day fasts more beneficial and with fewer side-effects. It’s only by being mindful and listening to our bodies that we can truly get a good understanding of it.


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