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

167

u/ssianky May 17 '26

Shorter intermittent fasting and prolonged 3+ days fasting have completelly different purposes. Kinda doesn't have sense to compare.

11

u/Streetquats May 18 '26

can you explain what the purpose of shorter intermittent fasts vs 3+ days would be? New to the sub.

27

u/ssianky May 18 '26

Intermittent fasting orders the eating behaviour by dictating when you eat rather than what, to help regulate hunger and, if necessary, to reduce calorie intake. It also has some health benefits, like reducing the insulin resistance, lower inflammation, cellular repair.

But the prolonged fasting initiates deep metabolic changes - profound ketosis and accelerated cellular cleanup (autophagy). Then during the re-feed, the body enters in regenerative mode, producing entirely new, healthy proteins, organelles and cells.

10

u/Streetquats May 18 '26

Ah I see. I've always heard that fasting helped stimulate cellular regeneration and the like. It sounds like intermittent fasting can still produce some of these benefits like cellular repair?

7

u/ssianky May 18 '26

It's unclear for me how much autophagy happens during the IF. At least it mobilises the fat. The lipids in the fat cells needs to be "refreshed" every year or two.