(CNN) -- The Daily Mail headline read "The Hangover ... Part 4: Bradley Cooper morphs into Zach Galifianakis as he arrives at the Met Gala with bushy beard."
With his obvious weight gain and scruffy beard, Cooper is looking quite different these days, but taking it to the Galifianakis stage might be a bit much. The "American Hustle" star has reportedly beefed up for his role as the late Navy SEAL Chris Kyle for the forthcoming film "American Sniper."
"He put on like 40 pounds," co-star Eric Close told E! "He's really been working hard. He looks great. He's really taken on this character. ... He really takes this story personally and wants to do an honorable job for Chris' memory and for his family."
Recent photos of Cooper show him sporting quite a bit of muscle along with the facial hair, the latter of which is way more familiar than the brawn. But the actor has been serious about his physical fitness for a while and once gave Men's Fitness his Top 5 workout tips.
He advised not cheating on a diet "(for) at least six weeks. It's vital you allow your body to rid itself of toxins and keep your hormones at optimal levels." He also told the magazine that "sugar and processed food cause your body to respond in a way that prevents proper muscle growth."
On Monday night, Cooper showed off his new form in formal wear at the Met Gala in New York with his girlfriend, model Suki Waterhouse.