Chris Pratt
Pratt played the goofy, chubby, cute doofus in virtually everything he was in before Guardians of the Galaxy. Evidently, Pratt spent three to four hours a day focusing on losing weight for his role every day. He lost 60 pounds of fat and bulked up at the same time.
How'd He Do It?
Disney hired the same Navy Seal trainer that worked with Chris Hemsworth to turn him into Thor. Pratt completely changed his lifestyle and diet overnight. After he made the transition, he stated that he wants to stay ripped for the rest of his life.