Emily Blunt Reveals Cillian Murphy’s Strict Oppenheimer Diet

As for how much weight he lost? Murphy opted not to share a number, explaining, “Ach, no. I don’t want it to be, ‘Cillian lost x weight for the part.'”

In addition to his physical transformation, the 47-year-old said the fast-paced filming process allowed him to embrace the character a lot more.

“It’s like you’re on this f–king train that’s just bombing,” he told the outlet. “It’s bang, bang, bang, bang. You sleep for a few hours, get up, bang it again. I was running on crazy energy; I went over a threshold to where I was not worrying about food or anything…But it was good because the character was like that. He never ate.”

Oppenheimer hits theaters July 21.