This sounds at least to me an awful lot like disordered eating. If it works for your, fine, but anyone else reading this should take caution and consult a physician before attempting anything like this. I'm worried that some of the tech trends around intermittent fasting are starting to sound like dieting advice form teen magazines in the late 90s and early 00s.

From the environment in which early humans evolved, it is far more disordered to eat 3 square meals a day.

I'm not arguing that 3 meals is the best pattern of eating, I'm saying that advocating for and glamorizing someone only eating every other day looks a lot like the way anorexia presents among dieting influencers today and teen magazines of 20 years ago. It's clear where that path leads, and I'm urging caution.

This is also just an evolutionary form of the appeal to antiquity fallacy. I might also point out that we have no clue how early humans apportioned meals throughout the day.

Except I am not advocating or glamorizing anything. I have no idea where you think "that path leads" or why you are equating having dinner every other day with having a disorder, anorexia of all things.

Like I said, you should do what you think is right for you but I'm cautioning other people that only eating every other day is a classic sign of an eating disorder. Again, you may well be fine and getting enough calories I'm not judging you at all. Classically things like skipping meals and fasting aren't determinative of disordered eating by themselves, no one would say that fasting for religious purposes is a disorder but this kind of behavior in the right context can very quickly tip in a bad direction.

I'm again not trying to say anything about YOU, only cautioning other folks here that the intermittent fasting trend among tech folks looks a lot like social trends among other populations that turned out to be very unhealthy and that people should be cautious.

> Where is the limit?

You lose roughly ~0.75 lbs of body fat at normal fasting levels assuming a reasonably active regular sized person. So how ever many days worth of body fat you would like to gain and lose regularly. You would have to eat back the same amount and probably wouldn't want to gorge yourself too much. A reasonable practical limit might be 5 days.

All of that assumes that you want to maintain a set weight. So the real limit is how much you want to eat in a single sitting. Take those calories and average them across as many days as needed to maintain weight.

Can you explain the .75lbs number you provided? How often do you anticipate a person to lose that much? Care to provide literature for your claims?

Not the GP, but a pound of fat = 3500 kCal. If you use the standard 2000 kCal / day basis, that gets you to .57 lbs fat loss per day.

Also, the 450 pound (204 kg) man who did not eat for an entire year [0] lost 0.72 pounds / day.

[0] https://pmj.bmj.com/content/49/569/203

That person seemingly turned his health around from 456 lbs to 180 lbs. But he died at age 50. I am scared of fasting because I dont think there are enough studies on humans to understand the long term effects like gallstones and lean tissue loss, especially heart muscle.

[0] https://en.wikipedia.org/wiki/Angus_Barbieri%27s_fast

He represents such an extreme case, it is hard for me to draw any broad conclusions from his life. The man never had a healthy relationship with food.

1lb of body fat is ~3500 calories. An average person doing average things burns around 2000 calories. You can easily put in your own numbers and get your own results. Just calculate your TDEE(total daily energy expenditure) and look up how many calories in a pound of fat to whatever tolerance you want.