Pitt was a` known exercise fanatic before fight club, as others have said for the movie he'd have a high end PT plus best of food and the time to eat it. He is small in the movie, doesn't look like he's hit up too many heavy squats or deadlifts but has more upper body mass than most non teenagers achieve training naturally in their first year or two. There's a chance he juiced for fight club, but I wouldn't bet on it. As for Troy, he goes from maybe 160 ripped in snatch to what looks to be 180 plus with a years training, I very much doubt that was a natural transformation. Obviously you can get to 180 at 5'11 without gear, but understand for the vast majority of people thats gonna take years of consistent training and diet.