5 day fasting experiment results

I originally posted this on Facebook, but now think it might be more interesting for the wider Internet community.

About 2 weeks ago Adriana and I finished our 5 day fast. It consisted of only water, (black) coffee, and tea. The main reason for us trying this type of fast was for general health improvements related to longevity (see bottom of post for references). Overall it was a positive experience and not as difficult as we thought it would be. This could be due to us already practicing ‘intermittent fasting’ for about a year now. The biggest surprise was how different our experience was compared to other people’s experiences — no ‘clarity’ or ‘energy high’ moments. Although we both lost some weight and body fat, I wouldn’t recommend it as a way to lose weight. It isn’t a sustainable way to lose weight. But if you’re interested in the health benefits of fasting (one of them being cell autophagy), then do your research and try it out at your own risk. 😎

Before and after ‘health’ metrics

  • 74–75 kg | 64–65 kg
  • 17–18 % | 29–31% body fat
  • 77–78 % | 64.7–66.6 % muscle mass
  • 60–70 | 75–80 resting BPM
  • 6.0–6.6 | 6.1–6.4 m/s PWV

Post-fast (2 weeks after):

  • 71–72 kg | 62.5–63 kg
  • 16–17 % | 28–29 % body fat
  • 78–79 % | 66.5–66.8 % muscle mass
  • 70–75 | 70–75 resting BPM
  • 6.3–6.5 | 5.8–6.0 m/s PWV

I did have a post-fast blood test and all the signals are in the normal ranges. Unfortunately I didn’t do a blood test pre-fast, so it is hard to compare my blood results this time around.

I have been to the gym a few times post-fast and have found that my strength and endurance has diminished a bit (around 30–40%), however it is also rapidly improving to near normal levels as I continue to re-feed. I predict I’ll be back at normal gym strength and endurance within 2 weeks.

Note: I caught a cold/flu post-fast which could be due to a diminished immune system post-fast. This also likely has affected my strength and endurance, so in normal post-fasting circumstances gym strength and endurance probably won’t be reduced so drastically.

Lessons learned

  • For both of us, it seems that our coffee consumption has also reduced since fasting. This could be due to consuming less coffee than normal during the fast, reducing our body’s reliance on caffeine.
  • Although it was a 5 day fast, the entire process is a lot longer. Re-feeding and restoring our physical stamina (e.g. walking up stairs) took a few days. Restoring gym strength and endurance is still on-going after 2 weeks of re-feeding.
  • Our mental stamina and focus restored quite quickly shortly after our first meal.
  • Having a partner to do it with helped a lot. We could motivate and keep watch over each other, and also share/compare what we were feeling during the fast.
  • We were mainly hungry between 3pm-7pm. This is pretty close to our normal feeding time during ‘intermittent fasting’, which is interesting as our bodies seem to be used to the intermittent schedule.

Day by day breakdown

Day 1

Day 2

Day 3

Day 4

Day 5

Breaking the fast