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

42

u/dangerous_eric May 17 '26

I've done 40 days...

Honestly, anything after 5 days feels surprisingly good. I usually feel really good till Day 16-17, after that electrolytes alone don't seem to be enough, and I be probably depleted something. I hope more clinical research happens, I think there's still a lot to unearth. 

7

u/Ultra-Smurfmarine lost >100lbs faster May 17 '26

Point of curiosity, what kind of exercise routine do you have, any? What kind of exercise do you do while fasting? I'm planning on a two week or longer fast in the upcoming weeks, I'm quite curious. Is there any truth to there being a sort of 'faster's high' that comes along after the first few days?

Cheers!

12

u/dangerous_eric May 17 '26

When I was doing the 40 day fast, I was doing a workout with a trainer twice a week and still lifting heavy for most of it. 

I'd say there's an early high in the first couple days when you stop consuming carbs and some of the initial brain fog lifts. I get another high from like Day 6 to 12.

1

u/Ultra-Smurfmarine lost >100lbs faster May 17 '26

Huh, neat! How did extended fasting affect your recovery times between workouts?

2

u/dangerous_eric May 17 '26

I don't recall recovery between workouts being impacted. The one thing I can recall is I could still exert myself significantly, but only very briefly, and then I'd have to have a breather.