[chaosagent]

We were always taught the rule of 3’s.

3 minutes without air
3 days without water
3 weeks without food.

[Waverunner]

I think it’s like the rule of 6’s now.

6 minutes = irreparable brain damage/death

6 days = organ failures due to dehydration and thickening of blood

6 weeks = body has scavenged all it can from muscle and fat

[Secret Agent Man]

3 hours extreme cold exposure

[American Infidel]

We were always taught the rule of 3’s.

3 minutes without air
3 days without water
3 weeks without food.

The longest recorded fast in human history was 382 days, but the man who did it, Angus Barbieri, weighed about 450 pounds, so he had plenty of "stored energy" to spare.

Angus Barbieri's Fast

I have personally done 5-day fasts and I currently do a quarterly 72-hour fast as well as 2 fasts per week of at least 36 hours. Obviously this is nowhere near 3 weeks, but I know of people who have done 28-day and 40-day fasts as well, consuming only water, tea/coffee, electrolytes and vitamins. There is another man in more recent times (name escapes me) who documented his 55-day fast on YouTube.

I wouldn't even attempt 24 hours without water and will hopefully never be in a position where I had to do so.