Originally Posted by Pleasurepays

metabolizing fat for energy, catabolizes muscle no matter what.

if you are basically starving yourself and "exercising" - you are forcing your body to burn muscle and fat for energy. "exercising" has nothing to do with anything. you can lift weights 5 days a week and get smaller and weaker. "exercising" is still breaking your body down. and it still requires adequate calories from macro nutrients to maintain and repair.

your body has 3 primary sources of energy.... 1) blood sugar 2) muscle which is converted to glucose and 3) fat.

metabolizing fat for energy is the least efficient and less preferred source of energy. add a starvation diet on top of that, reducing your glucose stores and adding substantial exercise is going to result in significant muscle loss.

of course your muscles have memory and you quickly restore muscle mass there isn't much harm in that either, except for the fact that your heart is also a muscle which will can also be significantly damaged as well, not to mention, you are devistating your immune system.