Bradley Cooper says it was “brutal” gaining weight for American Sniper.
The 39-year-old star plays late Navy SEAL Chris Kyle in the forthcoming feature.
He fully immersed himself in the role by eating more than double his daily caloric intake. But the actor admits packing on pounds wasn’t pleasant.
"It was pretty brutal," he told Entertainment Tonight about his diet and exercise regime.
“I gained about 40 pounds. I'm about 20 down from that now. I ate 5,000 calories a day and doing whatever I could to pay homage to [Kyle]," he added.
The film, directed by Clint Eastwood, is based on the best-selling autobiography of the late soldier, entitled American Sniper: The Autobiography of the Most Lethal Sniper in U.S. Military History.
Chris had the highest number of sniper kills in American history but was fatally gunned down in February 2013, allegedly by a veteran he took to a Texas shooting range to help deal with post-traumatic stress disorder.
The film is slated for release next year.
Bradley meanwhile can next be seen in director James Gunn’s Guardians of the Galaxy.
The actor lends his voice to the sci-fi mutant character Rocket Raccoon and recently admitted he felt the part was meant to be, as his role was inspired by a classic 1968 song by The Beatles.
"This is actually kind of crazy. Talk about a weird thing. Rocky Raccoon is one of my favourite songs," Bradley told MTV News late last year.
"For some reason, [the song] just f**king kills me. It's pathetic; it destroys me. When the role of Rocket Raccoon came upon us, I was talking to James Gunn and I said, 'I'm doing this movie now, and we're always tripping on Rocky Raccoon. Isn't it weird that I'm playing Rocket Raccoon?' He told me that was the inspiration for the character, that song. I don't know if that's the truth, but it's what he said, which if that's the truth, it's kind of insane."
The Marvel film is scheduled for US release next month.
