Food intake vs weight loss.

[Berry78 4,261]

When you don't eat, your body DOES lose fat and muscles, but holds onto Fluid so that's why the scale doesn't change.

Think of it this way. If we were a car, we could go quite a ways on a tank of gas. With no additional fuel, a car will just stop. Since we are alive, we don't have that luxury. Our heart has to keep beating. So we start "eating" ourselves. Sounds good if we only needed the stuff that comes from our fat reserves.

BUT, we need other things too, so the body will start breaking down our muscles, organs, and bones to get what it needs. The processes do slow down, but they never stop. This is why people can starve to death. Eventually one or more important chemicals will completely run out, and you die. Death happens relatively quickly if you eat nothing. If you eat just a little bit, then it takes longer, and what kills you is the fact that your body "eats" itself. It will take part of your organs, even your heart. So the organs get weaker and weaker, and finally quit.

http://pbrc.edu/research-and-faculty/calculators/fat-free-mass/