All the Wildly Dramatic Transformations That Helped Stars Win at the Oscars – E! Online

To portray the titular J. Robert Oppenheimer—the American theoretical physicist known as the father of the atomic bomb—the Irish actor underwent an extremely stringent diet. 

“Oppenheimer had a very distinct physicality and silhouette, which I wanted to get right,” the 47-year-old explained to The New York Times of the scientist, who died from cancer in 1967. “I had to lose quite a bit of weight, and we worked with the costume and tailoring; he was very slim, almost emaciated, existed on martinis and cigarettes.”

Thus, throughout filming, Murphy existed on little else. 

“He had such a monumental undertaking,” Emily Blunt, also up for Best Performance by an Actress in a Supporting Role thanks to her portrayal of his wife Kitty, told Extra. “And he could only eat, like, an almond every day.”

And, yes, he acknowledged it was all a bit nuts. “You become competitive with yourself a little bit which is not healthy,” he told The Guardian, refusing to share just how many pounds he dropped. “I don’t want it to be, ‘Cillian lost x weight for the part.'”

Though he did, of course, gain the big prize. 

But before you see if he takes to the stage at Los Angeles’ Dolby Theatre, check out the other celebrities who have gone all in on a part and emerged with the big prize.