Fasting can lead to a significant loss of water from muscles, which may not indicate severe muscle atrophy.

“Yeah, so all of this kept, even after five years. You know, all of my muscles actually shrunk now, which is kind of weird to look because the volume of water that leaves your muscles when you're fasting. It really freaked me out last time. I was like, I just was sure that I was just atrophying like crazy. I was really, like, "I'd really screwed this one up."”