Nope. I actually experimented with this myself and have logs up with pics and dexa scans proving it doesn't. the beauty of fasting for bodybuilders specifically is you won't even come close to doing it. someone who is extremely malnourished? that is a whole nother ball game. but bodybuilders get so much nutrients already that fasting is actually a huge net positive in many ways including this one
Do you believe that Mother Nature designed us to store excess energy as fat, but as soon as we need it, we start burning protein instead of fat? No, protein is conserved and fat is burned for fuel during fasting.
In the first 24 hours after eating, you will use amino acids as substrate for gluconeogenesis. Afterward, glycerol from the breakdown of triglycerides provides the substrate. MUSCLE is actually conserved during fasting.
one of the other reasons is the rise in HGH during a fast. it skyrockets from 20 hours for 5 days straight up.
I challenge anybody to prove me wrong on any of this, don't just post "yes it does" and then walk away otherwise I will have to blast the shit out of your post with more science and facts