I'm not sure what exactly you are saying. Fighters rapidly lose fat weeks out from the fight and they don't lose muscle (then they lose water weight, which is irrelevant here).

The idea that you think 'fasting' loses muscle mass is an idea that is not backed up by any evidence. Fasting isn't a diet, it is about when you eat.

Also, you didn't source anything. Don't you think maybe the dozen people replying to you might be less likely to be 'making stuff up?'