Cillian Murphy spoke about his drastic Oppenheimer weight loss during an appearance on Jimmy Kimmel Live! Thursday night. Sitting alongside his co-stars Emily Blunt and Robert Downey Jr., Murphy admitted he didn’t enjoy losing so much weight for his Oscar-nominated role even though it helped him get further into the character of Robert Oppenheimer.
“He was insecure about his physicality,” Murphy explained of the real Oppenheimer. “But you had this hugely strong mind and this really frail body, so it was useful.”
Murphy not only had to lose the weight, but then work for the entire shoot to keep it off. By his own admission, he eventually stopped tracking how much weight he shed. “It wasn’t registering on the scale?” Downey joked.
But Murphy was entirely serious, telling Kimmel when asked about his least favorite part of the transformation, “All of it! I didn’t enjoy any of it. I don’t recommend any of it,” he said definitively.
“I think it’s going to bed hungry,” Murphy said of his least preferred element. “I wouldn’t do that by choice,” he explained, before adding, “It was always cold. I sound like Tiny Tim or something.”
Although he was uncomfortable for the entirety of the 57-day shoot, Murphy appreciated the immersion into his character. He recalled one particularly grueling but rewarding passage of production where Nolan’s directorial tactics and his weight loss came to a brilliant head.
While shooting the interrogation sequences that bookend the movie, in which Oppenheimer faces a counsel determined to strip him of his government credentials, Nolan kept the air conditioner running full blast to keep Murphy on his toes.
“Chris liked to keep the A/C on during that particular part of the shoot,” he explained. “I think because the character is being humiliated and he feels awful, and I was so hungry and so cold, it kind of helped.”
“My wife is always cold and I’m never cold,” Kimmel comforted the actor. “I have a thick layer of fat keeping me warm.”
Robert Downey Jr. then piped up to throw their co-star, and Kimmel’s faux nemesis, Matt Damon under the bus. “Correspondingly, Matt Damon played Groves, and Groves was quite rotund,” he offered. “I don’t know if Matt really took it upon himself to gain the right amount of weight.”
Oppenheimer is currently streaming on Peacock.