Try it. Ive done 1 week water and coffee only fasts. You stop being hungry after 3 days or so

Same experience. For colonoscopies, instead of all the drugs I just don't eat for three or four days. Stop being hungry late on the 2nd day. Eating after that is just habit, trying to remember not to graze.

Try it, yes, but only if you have sufficient fat stores, lest you lose muscle instead.

If you are fasting for the purposes of losing weight, it literally is the last thing that matters.

Also lifting while in a fasted state is a thing, to prevent this exact scenario.

What would you say is the best benefit for you?

As someone who regularly does 24-36 hour fasts (alternate day fasting), it's not as difficult as you'd think. For me at least some of the weird/unexpected side-effects (insomnia being my major one) are harder to deal with than the hunger pains. I generally will have less energy at the gym on fast days but even that can vary and you have more than you'd expect.

One thing I've come to learn from doing this for years is our bodies really accept fasting well...which makes sense from an evolutionary perspective. We really are "built" to fast.

> 500 calories in one day

Especially since they weren't looking to lose weight, since they were not obese. It's likely the weight loss was due to muscle loss, and not fat loss.

>It's likely the weight loss was due to muscle loss

You think your muscle is deteriorating within days of a caloric deficit?

Not sustainable at all, the weight will more than likely come back super fast. A diet is something that you should be able to sustain over a long term

In TFA they state that the weight loss was an incidental part of the experiment and in fact they thought they would gain weight.

As it turns out, the body obeys thermodynamic laws and you will lose weight if you eat less than you burn even if its all starches and sugars.

Except that the body is not a passive black box and can adapt its burn rate - which is partially uncontrollable (meaning: not related to physical exercise, e.g. thermal regulation)

Burn rate for a sedentary 75kg human is 1600-2000 kcal/day iirc. It can't go down to 500 without dropping active tissue

If they honestly thought that while eating 500 calories I would just write off everything else they claim as total nonsense