15. Mark Wahlberg
Mark Wahlberg has always been in good shape, but he too had to go through serious body transformation for his role in Pain and Gain. Mark remarkably raised his fitness to a new level while undergoing weight-loss and building muscle mass in order to gain the strength for his role as a fighter. He would train for 5 days every week, and consumed more than 10 meals daily to ensure that his muscular figure was well-maintained throughout the shoot.