01/12/2011 08:15 am ET Updated May 25, 2011

Zac Efron Puts On Big Muscle: Buff Up For 'The Lucky One' (PHOTOS)

High school no more! Zac Efron has buffed up big time.

The former 'High School Musical' franchise star has been seen out in Hollywood of late looking sculpted as never before. Turns out, he put on 18 pounds of muscle for his upcoming film, 'The Lucky Ones,' about an Iraq War veteran.

When asked by E! Online how he did it, the answer was simple: "I was just eating, eating and eating."

Whether Zac is moving on from his HSM days is up in the air -- in December, he and longtime co-star and girlfriend Vanessa Hudgens broke up, but it seems of late that they are getting back together.


Zac Efron Buffs Up