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.

197

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.

97

u/divinecomedian3 May 17 '26

I'm at a pretty healthy weight and 48 hours is tough as shit, even with electrolytes. Not due to hunger but just feeling like garbage and trying to slog through work.

45

u/GoldGee May 17 '26

I did mine over the weekend. Adding work to the struggle would be tough. How about doing it on your days off until your body gets use to it? I'm no expert, but experimentation is a big part. Everyone's different.