Will Smith gained 26lbs to play Muhammad Ali in "The Greatest", think he did it naturally? Doubt it. Also Nicholas Cage, people think he was pretty big in "Con Air", but there was some movie he was in with David Caruso and was the son of a mob boss, can't remember the name, it's almost ten years old. But no one will ever convince me he wasn't verry jacked up, he was big as hell and his face was completely bloated. I think alot of them do whatever it takes to get ready for these roles as quick as they can. And athletes, at the elite levels, it's probably more like who doesn't.