BRADLEY Cooper ate four times the recommended number of calories per day to prepare for his lead role in American Sniper, it has been revealed.
The Hollywood actor put on more than 40 pounds (18kg) to play late Navy SEAL Chris 'Legend' Kyle in the Oscar-nominated film, while also adhering to a strict fitness regime.
"He was eating about every 55 minutes or something like that, and I want to say it was about 8,000 calories a day," writer and producer Jason Hall told People.
"Bradley used his own trainer, who was busting on him. I think he was working out four hours a day for several months. He was determined to do it naturally, he didn't want to use any hormones or steroids or anything."
In dedication to the role, Cooper watched hours of real footage of Kyle to make his portrayal as accurate as possible and worked with a vocal coach twice daily to sound the part too.
"There were moments where they'd get him at a certain angle and you just felt Chris, you felt the essence of Chris," said Hall. "Standing behind the monitors, I'd just get goosebumps rushing up my legs."
Coper is up for best actor at next month's Academy Awards, when he will compete with British actors Eddie Redmayne and Benedict Cumberbatch.
American Sniper broke US box office records last weekend to score the highest-earning January opening with $99.5 million.
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