1. Christian Bale - The Machinist

One of the most extreme transformations was Christian Bale's weight loss for The Machinist. The character Trevor was written for a short man, and the aim would have been to get him down to just 120 pounds to avoid looking too extreme. But this was a challenge that Bale, ever the physical chameleon, insisted on undertaking himself. In fact, his co-star Michael Ironside remembered Bale insisting, "No, don't change the weights. I want to see if I can make them." Bale again lost weight after bulking up for Batman Begins for his role in The Fighter.
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Edited by Sarah Nazamuddin Harniswala