you have to fast greater than 20-24 hours to lose some muscle. then once you get to day 2-3 the amount of muscle lost becomes minimal and your body switches to fat stores.
if you did nothing but grow muscle nonstop you would end up 1000 pounds of muscle and let's be honest you would be dead. your body needs to experience catabolism and anabolism.. you can't just be anabolic forever, it not only is impossible but it is also very dangerous even if it was possible..
over the long term fasting for long periods of time will result in MORE MUSCLE. but Steve you are full of shit, how can fasting lead to more muscle? the answer is very simple and people need to think outside the box on this shit.. you will lose the weaker and old muscle tissue when you fast and then you will grow back newer and better muscle. so really you are swapping out the bad and swapping in the good. your skin, and all your cells within the body will do the same thing. so you will look tighter and be much healthier in the process. this is why i advocate everyone should fast. even if you are a pro at the highest level, or you are some skinny newb. fasting will benefit anyone