Actor Rob McElhenney on set as Mac showing off his abs after insane weight loss transformation in the TV series it's Always Sunny in Philadelphia (Image: FX) ‌ ...

To gain the weight, you ate five 1,000-calorie meals a day. What were they? ROB MCELHENNEY: As I started off I was doing it with chicken breast and rice and vegetables.

McElhenney's first major acting role was in the 1997 thriller, “The Devil's Own,” alongside actors Harrison Ford and Brad Pitt. McElhenney was slated to play a minor character named Kevin.