When it comes to losing weight healthfully and sustainably, experts warn against following extreme diets. But resorting to calorie restriction at the risk of malnourishment is no foreign tactic among celebrities seeking to prime their bodies for movie roles. Stars from Anne Hathaway to 50 Cent to, most recently, Chris Hemsworth and more have all slashed their daily caloric intake to shed pounds fast.

Here’s how those three celebrities, plus seven others, either dropped or gained pounds fast—and for which roles: