How Do Movie Stars Lose All That Weight For Roles? [Watch]

Sometimes I watch TV or a movie and I think (as I pound my Ben & Jerry's) "Damn, I wish I was just hot like Beyonce... she doesn't even need to try. She's just perfect."

Well, apparently it's not as easy as I thought. They're all pretty hungry all the time... except for The Rock... he has way too much to eat!

Check out the video:

What's your go-to diet?  Is there something special you do when you have an event coming up?