Jim Spellman / WireImage 1 / 16
Jim Spellman / WireImage 1 / 16

Actor Zac Efron gained 25 pounds for his new role as a Marine in "The Lucky One," and part of his regimen involved by guzzling a chicken puree.

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The "High School Musical" hunk stars in the upcoming film adaptation of Nicholas Sparks' best-selling novel about a Marine who searches for the woman he believes is his good luck charm, and Efron felt he needed to beef up to make his portrayal a convincing one.

He tells Cosmopolitan magazine, "We met with a bunch of staff sergeants at Camp Pendleton (in Southern California). Most of them were my height, but they really had a lot of extra weight on them. So, for the role, I must have put on 25 pounds."

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The actor says he had to find creative ways to help pack on the bulk because he was simply tired of chewing all of his food.

Efron says, "If I could lay out on a table what I ate in one day, your jaw would drop. It was thousands and thousands of calories. One day I put three chicken breasts into a blender and hit 'puree' because I just couldn't chew. Chewing was taking so long!"

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