22 Unbelievable (and Crazy) Movie Transformations (PHOTOS)

To play IRA hunger striker Bobby Sands in the 2008 Palme d'Or winner Hunger, Michael Fassbender dropped about 42 pounds from his formerly 170-pound frame. Production shut down for 10 weeks before filming on the final act began, and Michael rented a place near Venice Beach where he could exercise and watch his weight with hawkish dedication. He told the Telegraph, "It was the perfect place because I was just another freak on the beach, power walking."

He subsisted on 900 calories a day for the first five weeks, eating mainly berries, nuts, and sardines, and then he cut back even further. For exercise he skipped, did yoga, and walked. "It is such a psychological prison. I had to calorie-count, and I'd catch myself every now and again picking things up in shops, reading the label and putting it back — and wonder what I looked like. You're totally focused on that, obsessing about numbers."

Looking back, he recalls, "I felt pretty strong — but hungry."