Insights into an 86-hour Fast

I’ve been fasting a lot over past couple of months…

I first started practicing intermittent fasting in 2014. It was about the same time when I started doing the ketogenic diet. Keto+IF are a killer combination. I wrote about my experience with this combo.

The protocol that I began with was 16/8 but since this was really easy with keto, I continue with 18/6 for a long time. I would also do 20/4 and OMAD (one meal a day every now and then). This led me to researching prolonged fasting and after reading more than 230 studies and books on the topic I wrote a book on the subject. In the book I also document a prolonged fast I did in 2014 — a 5-day water fast.

Then around 2016 I stopped being strict keto and was more sort of low-carb with 3 meals a day. I would frequently be out of ketosis — and I learned that was no fun because hunger pangs and irritability would creep up throughout the day. Mind was not as clear, sleep was not as good and energy levels weren’t top either — compared to formerly being strict keto. I would be eating loads of plant foods — and that was far from optimal for me.

December 2017 was my comeback to keto — in full force. That’s when I bought a blood glucose ketone meter and I started measuring ketones every day. I still do to this day. I wrote about my keto experiences on my personal blog. I also started experimenting with the carnivore diet in August 2018 and I was on the carnivore keto diet very strict for 6 months. More about these experiences on my Youtube channel. At the same time, I would begin doing IF, usually 16/8 with 2 meals a day.

Early in 2019 I started having at least 2 days of 24-hour fasts per week, usually on Wednesdays and Fridays. Aside from that, I would be doing 24+ hour fast quite frequently — when traveling intercontinentally. I usually don’t eat when I fly. But I start the fast a day before the flight and prolong it until next day after reaching my destination. So, this almost always led to 40+ hour fasts. That’s was really easy for me due to keto-adaptation — I suspect.

Long story short, a trip to England made me think of doing a 60 hour fast. That would not be difficult. I started on Sunday evening, after my last meal — around 10 o’clock. The flight was on Tuesday evening — a breezy 2-hour and 40 minutes flight. Since I would be arriving late night in London, I would continue my fast until Wednesday. But I ended up prolonging it until Thursday morning at 11 AM. So, a total of 86+ hours. Now, there are a couple of points that I want to make…

The purpose of my fast was simply health. I learned that food restriction is good for the body and for the mind. Plus, as one of my friends say, any kind of prolonged fasting (that’s more than 48 hours) resets your entire relationship with food and makes you rethink the deeply ingrained concept of the necessity of eating multiple times a day at regular time intervals.

I don’t need to lose weight. In fact, I want to regain some pounds, which is one of the reasons I stopped the fast at 86 hours.

Ok, one of the points that I need to make is about what I allowed into my mouth throughout this fast. So, water and coffee (black — americano — once or twice a day), supplements (magnesium, D3, omega-3, zinc and vitamin C), and a bouillon cube dissolved into a cup of hot water (for salt). I would also chew orbit-gum a couple of times a day. So, this was pretty much flexible so to speak. That’s probably one of the reasons why it was so extremely easy for me.

I am still pretty much mind-boggled by the fact that at no point during the fast I had thoughts about food or I felt hungry. It might have been because of my body being used to fasting and also to burning fat as per the combination of keto+IF. Ketone levels about 24 hours into the fast were around 1mmol/L while BG was into the low 70s mg/dL. At 60+ hours they were:

Another thing that I want to mention is about my energy levels which were quite high throughout the whole time. My mood was very stable and elevated and I did not have energy crashes or low energy moments. Coffee might have helped. I need to mention as a coffee drinker my entire life, I went cold turkey in 2017 up until this year when I started drinking it every now and then — once or twice a week (during OMAD days). Quitting coffee was a good decision, at least for my sleep and my renewed intention with this substance is to use it infrequently. With this prolonged fast, I had coffee every day — and it felt okay.

I did not exercise (strength training) but I did a lot of cardio every day — in the form of walking. I kept myself busy, in meetings with people, working on personal projects as well as the whole traveling thing, which probably kept my mind very far away from thoughts of food. Again, I reiterate — keto-adaptation is probably central to this no-hunger thing.

But not everything was fine and dandy. My sleep suffered. I track my sleep with Fitbit. I had little deep sleep (36 mins on Sunday night, 45 minutes on Monday night, no accurate sleep data on Tuesday night and 22 minutes on Wednesday night). I usually have around 1-hour of deep sleep.

So, Fitbit wasn’t able to get accurate sleep data on Tuesday night (“Wed” in the image above) because it couldn’t get a consistent heart-rate reading during my sleep (it happens sometimes).

Ok, for context, I usually hit my sleep goal (7-hours asleep) at least 3 times a week. I need to work more on this…

My sleep suffered with this fast but it’s not that I felt it. I was really energetic even when I went to bed. And like I said above, it didn’t lead to fatigue or low-energy. It’s probably the fact that your body is not busy with digestion and has more energy — just a theory of mine. This is about the same sleep experience that I had when I did the 5-day fast in 2014. But then I also had headaches a couple of times during the fast, which were completely absent from this fast. So, in short, I’ll be looking for ways to improve sleep (if possible) during prolonged fasting.

The numbers right before breaking the fast were:

And I broke the fast unceremoniously with around 2,000+kcals worth of mixed nuts, cheese, peanut butter, and dark chocolate. I would be much more careful with breaking the fast when doing 5+ days of prolonged fasting.

At the time of writing this I’m 6–7 hours after that meal, I feel really good. The meal was super satisfying and I feel like fasting until tomorrow, but that’s a no-no. I need to gain some pounds so I’m probably going to have a late meal the carnivore style — steak and eggs and probably some cheese.

In my future fast, it is likely that I’m going to try to experiment with less flexible protocols and see where they lead. So, stay tuned for that!

I document glimpses of my life on my Instagram so you’re more than welcome to join me there. And also please tell me of your fasting experiences in the comments below. Be well!