Go Fast or Go Home

In this blogpost I'm sharing my experiences with fasting. I'm going to try to do a long fast (probably 5+ days), but it all depends on how I feel. I'm not going to force things - it has to be healthy after all, but I'm sharing all my thoughts and feelings during my fasts here.

Go Fast or Go Home

Normally I only write about tech and my side-projects here. Let's try something different.  

In this blogpost I'm sharing my experiences with fasting. I'm going to try to do a long fast (probably 5+ days, but I secretly want to experience a 10 day water fast), but it all depends on how I feel. I'm not going to force things - it has to be healthy after all, but I'm sharing all my thoughts and feelings during my fasts here.

Now that the gyms are open again, I decided to get back in shape and live healthier. For me, that means:

  • workout regularly, preferably a HIIT workout or strength training
  • eat cleaner, and try to be in keto most of the time
  • take a close eye on water intake and get those liters in
  • sauna multiple times a week
  • meditate
  • do some rolling fasts or intermittent fasting
  • limit caffeine intake

Past Experiences with Fasting

I started experimenting with fasts in 2018, first with intermittent fasting. Intermittent fasting is a fasting protocol where you can only eat in a specific time window. The most popular is 16:8, where every day you fast 16 hours, and are allowed to eat in a time window of eight hours. Taken into account that you shouldn't eat too close to bedtime, that time window is probably somewhere between 12:00 and 20:00, which is plenty of time.

I don't, or very rarely at least, eat breakfast, so that was an easy one. 16:8 became 20:4 (only eat in a 4 hour window), which became 22:2 and ultimately 23.30:30.

The next step was OMAD, or One Meal A Day. When you're doing 22:2 IF (Intermittent fasting), you are probably already eating only one meal. So that one was easy.

And then came the real fasting experiments.

24h+ fasts

NOT eating for more than a day. Is it even possible? Turns out it is.

But is it healthy?

There are a lot of sources on the benefits and concerns of fasting. There are two I regularly read/watch: one is Thomas Delauer on Youtube and the other one's Rhonda Patricks' Found My Fitness.

Especially Dr. Rhonda Patrick, who has a Ph.D in biomedical science and knows all about nutritional health, the brain and aging, objectively shares research results on all things personal health. And she has this great talent to convey the information from the research in a way that makes it digestible and understandable for a novice like me.

In order to minimize the risk of me giving wrong information, I'm just going to link to these awesome resources:

There are a lot of benefits to fasting, so I started experimenting with it. 24 hour fast became 36 hours become 48 hours.

48 hour fasts were becoming easy to do. I sprinkled in a 72 hour fast here and there, but these were harder.

And strangely enough, I got more energy the longer I was fasting, but I just had the urge to eat something. In the end, I was thinking about food all the damn time.

And then one time I did a 5 day fast. The curious thing is the emotional rollercoaster I went through:

  • day 1: everything feels normal, normal energy levels
  • day 2: little bit hungry, feeling a bit sluggish
  • day 3: amazing energy levels, not hungry at all
  • day 4: normal energy levels, started thinking about food a lot more
  • day 5: felt bad, even dreamt about food. I NEED TO EAT

So that was my one time experience with a 5 day water fast.

The Fridge is Empty

I'm ready to start my new fasting journey.

Again, I have some goals (I want to go for a 5 day fast, possibly longer), but I'm not going to force things. I'm also honestly gonna share how I feel, so I'm not "keeping up an image". If I can't make it to 5 days, so be it.

The next coming days I'm only going to drink water and cold brew coffee (no milk and sugar of course). I'm taking the following supplements: vitamine C, vitamine D, electrolytes (calcium, magnesium, potassium, kalium), and boron.

I can also drink tea and sparkling water.

I'll still take a sauna every few days, but have to make sure I take my electrolytes afterwards and drink around 1L of water in the next two hours.

On day one I'm definitely going to the gym, but it's possible in the next few days that the only exercise I'll get is walking.

July 30, 2021: Day 1 of Fast


Alright, it's now July 30, 13:52. 4 hours ago I had a piece of dark chocolate, and that's the only thing I had for today, so I've been fasting for 4 hours.

It's only been 4 hours but still feeling good of course (still got the energy from my dinner last night). Going to the gym in a few hours.


Just got back from the gym. Had a good HIIT workout. I use the 4x4 HIIT interval training by NTNU, the Norwegian University of Science and Technology.

It consists of a 10 min warmup, and then you constantly switch between 4 minutes at high intensity, reaching 85-95% of your max heart rate, and then 4 minutes active break at around 60% of your MHR.

You can calculate your MHR by subtracting your age from 220, in my case it's 190. (I'm not yet 30, but 190 is easier to use in calculations).

A heart rate of 180, as you can see in the chart below, is right at 95% for me.

Afterwards I took a normal shower, then went in the Turkish steam bath for around 20 minutes and finished off with a cold shower.

Now it's case to:

1) drink a lot, because I lost probably a liter of sweat during my workout

2) take electrolytes, as you lose electrolytes like potassium, sodium and magnesium in the sweat you lose.

You lose potassium the fastest during a fast, and as you don't get any food intake with potassium, you will need to take some as a supplement.

The thing with electrolytes is that they also influence the hungry feeling you get. I read this somewhere, so I don't know the correct source, so don't quote me on this. But experience tells me it's true. Whenever you get that hungry feeling, just drink water and take an electrolyte supplement. The hunger goes away. Thomas DeLauer mentions something like this in his video on fasting 101.

Now fasting is supposed to be difficult, so I'm not gonna pop an electrolyte every time I get somewhat hungry, but as I just had a good workout, replenishing my electrolyte balance is very important.


Just got back from a walk with a friend. It was a little less that a 5km walk, so not that far.

On the way back home I passed a restaurant, and the food smelled delicious. But I'm not even hungry right now, so it was no biggie.

The rest of the night I'm gonna watch the recap of the Chess World Cup on YouTube, and then read a bit and doze off. Hopefully I'll wake up tomorrow with enough energy to get a workout in.

So I'm currently at 12 hours fasting. Everything's going great. I'm not hungry, but I could eat something, so it's definitely only a mental thing.

See ya tomorrow

July 31, 2021: Day 2 of Fast


Currently at 26 hours, which means I'm now in ketosis.

Normally your body uses carbs to burn for energy. But as you're fasting, you don't get any carbs in. That's why your body has a second way of getting energy: by burning fat. It burns fat to make ketones, and then uses those ketones for energy.

So my body is using its own fat to do its daily business. That's a very cool side effect of fasting.

Overall I'm feeling good. Energy levels are normal. I'm seriously contemplating going to the gym to get another HIIT workout in.


Just got back home from an afternoon out with a friend.

Watched him eat a very delicious breakfast burger, but it did nothing to me, so that's good. I just drank a cold brew coffee.

Afterwards played some snooker, again felt good. No feeling of hunger or low energy.

Now that I'm at home sitting at my desk just watching YouTube, I do get the feeling of wanting to eat but it's more out of boredom. So I'm probably gonna go out for a walk in order to be out of the house.


Decided to go for a little walk. Felt a bit more exhausted afterwards than usual. Also smelling the great restaurants in the city center definitely didn't help 😅.

Got home, just ate some pure salt which helped a lot: all feelings of hunger are gone.

Now I have a green tea with ginger, which also helps with suppressing feelings of hunger, and took an electrolyte supplement.

Gonna work till 10 and then watch a movie and go to bed.

August 1, 2021: Day 3 of Fast


I woke up around 10am, not with the feeling of hunger, but with the feeling of an empty stomach. I had this very empty feeling in my stomach and there were some rumblings, but it's not that I had a desire to eat.

It felt like my body was saying: "Hey, your stomach is still empty", but not "Hey, your stomach is still empty so you should eat".

I feel my energy levels dropped quite a lot, so no workout for me today. So only a walk at night today.

Drinking my cold brew now, and already took my boron supplements. Gonna skip the vitamine C and D today.


Got home from a walk and was definitely feeling the effects of the fast when I got home. I was easy irritable, cold and my muscles felt fatigued. I didn't have any energy to do anything.

August 2, 2021: Day 4 of Fast


Hopefully this will be the worst day of the fast. I've got no energy, my muscles feel tired, and I don't have any focus at all.

I don't feel hungry, even though I could definitely eat some meat, but it's the side effects that are killing me.

I'm not planning on getting a lot done today. I don't think I'll even go out for a walk today.


Okay this is getting pretty hard to be honest. I think it's because I wasn't in keto before I started fasting.

The plan is to give it until tomorrow morning and if I'm not feeling better, then I'll eat.

It's not that I feel bad, it's just that I can't focus, think only about food, and have a solid case of the keto flu I think. Normally I'd try to break through it, but this is not a good time for me to not be productive, so it'll be for another time.

August 3, 2021: Day 5 of Fast


Okay, I'm a bit proud a managed to at least reach a 5 day fast, but I'm going to break it.

I got a bottle of broth, which is perfect to break a longer fast with. Then I got some slices of chicken filet and pork belly. I'm just gonna eat a bit, wait for an hour, then eat more, in order to not overfeed my body all at once.


Phew, this was much harder than I thought it would be.

I really wish I could share with you the experience of a 10 day fast, but I felt around day 4 this wasn't going to be a ten dayer.

I'm looking forward to do it again sometimes, probably at the end of August, and look forward to sharing my thoughts and feelings on it again here.

Now, where are those chicken nuggs??