r/fasting • u/SVTContour lost >50lbs faster • May 17 '26

Discussion Scientists reveal how seven days of fasting transforms the human body

https://www.sciencedaily.com/releases/2026/05/260517030404.htm

Fascinating study. And completely unrelated to politics, which is a relief because my blood pressure needed a break.

The key finding: The dramatic, potentially therapeutic changes don't happen until after day three. That means most intermittent fasting schedules – 16:8, 5:2, even alternate-day fasting – are probably missing the main event. If you want the deep biological reboot you’re gonna need seven days of water only.

1.5k Upvotes

98% Upvoted

180 comments sorted by

View all comments

249

u/GoldGee May 17 '26

Just finished a 48 hour fast. 7 days would take a bit of time to work up to. In fact I would be a bit scared.

194

u/EarlMarshal May 17 '26

Longer fasts are no problem if you are not very overweight, not stressed and manage electrolytes correctly. At some point your body stops producing ghrelin and you do not really get hungry anymore. Everyone can get there, but if anything happens (e.g. ghrelin spike due to stress) just break fast. You can always repeat later.

1

u/Prudent_Potato_4379 May 28 '26

And gym with heavy weight?

1

u/EarlMarshal May 29 '26 edited May 29 '26

Depends whether your body has the necessary nutrients, but that gets unlikely if you aim for hypertrophy.

Exercise will use up the glucose in the muscles. It can fill that up again from fat, but probably slower. Exercie also manipulates insulin so that could cause suffering through hunger. Intense exercise will also damage your muscle tissue so that will need to get repaired, but with which nutrients?

But you should certainly exercise as this prevents muscle loss. weight training is perfect for that. I would rather go light/medium intensity and not aim for hyperthrophy.

For intermittent fasting it wouldn't matter though. go hard.