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Comment by jhardy54 | Hacker News Reader

> I’ve read that there are limits to how much weight you can lose per week, no matter how much you restrict your caloric intake. Beyond a certain point, your body senses the deficiency and decreases your metabolism.

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The point is that there's a distinct physiological difference between no calories and some calories

That’s only true to a certain extent. After a certain point, no calories just equals rapid fat burning

No, not just fat, but all kinds of tissue including muscle.

Muscle is only burned when you are out of fat.

This is not true at all. There's perhaps a preference toward fat but muscle wasting absolutely occurs during fasting, and often at a relatively significant rate.

If you were to "run out of fat" entirely, you'd simply die with fairly significant caloric reserves in the form of muscle. This is not what is observed.

This is very much not true; I lost over 100lbs and saw the evidence in myself, before I adjusted and started eating a high protein low calorie diet. If you don't consume protein and don't work out, you will lose muscle mass, even if you have fat to burn. This is because muscle tissue is expensive to maintain; the body tends to reduce it if it's not being used.

your body is constantly using protein to maintain your muscle. When you starve your body of protein, you lose the ability to maintain your muscle, and your body begins to lose muscle as well, even though it does a bunch of stuff to try to stave that off.

Right. So you're not actually burning muscle - instead of fat - per se. Instead muscle wastes as the body isn't maintaining it.

While it's not a controlled study, History Channel's "Alone" (reality survivalist show) always touches on lack of food and its affects.

This just seems like a roundabout way of saying: water fasting results in loss of muscle and fat tissues. By the internal logic of this thread, and since I don’t see any way to intake protein on a water diet, where is the nuance?

they're splitting the hair between "muscle wasting" and "burning muscles". I don't know if its a question of internal logic or not. They are separate things, and when you fast your body does some stuff with HGH (which can skyrocket hundreds of percents) which I've read is supposed to reduce some of the expected muscle loss.

They're technically correct, the best kind of correct (?)

We completely agree - I was forcing myself to be less blunt, frankly. Well put.

The gist of my point is, the body can't use muscle as a replacement for fat. The best it can do is not invest in muscle upkeep, and redirect that energy / resources elsewhere.

I also tried water fasting. Lost both fat and muscle (and I still have plenty of fat)

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