Russell Crowe (Gained 63 Pounds)
Credit: Everett

What's with overweight CIA agents? Crowe packed on 63 pounds for Body of Lies (take that, Clooney). But given that he isn't really known for his body outside of the Roman Coliseum, he took getting fat in stride. Talking about his pre-production diet he joked, "I'll have that cheeseburger for breakfast, thank you!"

The Bottom Line:
You can gain weight eating healthy foods, but there's a reason so many actors choose less wholesome diets when they need to fatten up. "If you're getting calories from nutritious sources, you will be getting body signals that will support you in eating less," explains Bacon. "For example, if you eat fruits and vegetables which have associated fiber you get full quicker than if you eat the same number of calories in a sugared candy."