system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What would happen if someone who is obese starves back to normal weight?
gpt
Nothing good.

Fat cells act as storage for excess glucose, which can be accessed for cellular respiration. 

However, the body needs a range of amino acids and vitamins to function, which are *not* stored in fat.  Before you starve off the weight, your body will be reduced to cannibalizing muscle tissue for proteins, and even bone tissue.