How much weight in fat from a 7 day fast does a person lose?

Question

I’m assuming a person would lose “5 pounds” of water weight, so then that person would gain back those 5 pounds after ending the fast. 

How much fat would be lost though?

Update:

Also: would there be a large loss of muscle mass?

Answer 1

There is no equation that can tell you that.  It would depend on many, many factors.   

Answer 2

Theres really no way to know for sure. It depends on their metabolism, how active they are, how much fat they have to begin with, how much muscle mass they have, since a 7 day fast will also burn muscle, and what their liquid intake during that time is, since a week without water can lead to serious dehydration amd even death