Matt Damon: Robert De Niro Helped Me Pack On The Pounds For 'The Informant!'

Matt Damon in 'The Informant!' Warner Bros.Access Hollywood

LOS ANGELES, Calif. -- Matt Damon's boyish looks and svelte physique may have earned him "Sexiest Man Alive" honors in the past.

But in his new film, "The Informant!," Damon threw vanity to the wind and packed on the pounds for his role.

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"It was great," Damon told Access Hollywood while promoting the film at the Toronto Film Festival. "I wish they were doing a sequel because I ate whatever I wanted to and drank a lot of dark beer and put on 30 pounds. It was easy, shockingly easy to do actually."

However, a few inches around the waist weren't the only new addition to the actor's frame - he also grew out a mustache.

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"My wife liked it," he added. "You know, I liked parading around the house with my belly hanging out. I would do like kind of the sexy walk, but I clearly shouldn't have been doing that type of thing. We had fun with it. We laughed a lot."

In his preparation for the extra weight, Damon sought the advice of a fellow Oscar winner - Robert De Niro.

"I asked him what he could tell me about it," Damon revealed. "He had put on 60 pounds for 'Raging Bull.' He said, 'All I can tell you is the first 15 pounds are fun. After that, it's work.'

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"I found that actually the first 30 pounds were fun and then I just kind of left it there," he continued. "I wouldn't do more than 30 though - that would start to hurt."

Once filming for the movie was complete, it was time for the 38-year-old star to do something millions of others have tried, often without success - dropping the extra weight.

"Just a lot of exercise and watching what I ate," Damon explained of his diet regimen. "Unfortunately there's no magic bullet when it comes to weight loss - it just sucks."

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