Yep, like having pizza one time will turn all your muscle into fat. One time I had a cherry coke big gulp at my gym, and one of the trainers, told me "you know better than that" I'm at 9% bodyfat, and the soda didn't change a damn thing, I felt bloated for a day, had to pee like every ten minutes, but I set a new PR that day, probably all the caffeine and sugar. Now if I had cherry coke all the time, or this guy ate pizza everyday like Artie Lange, that we could turn into fat asses, but cheating once in awhile won't kill you, as long as you eat clean most of the time, and bust your ass in the gym.