“Extra” was on the set of Gerard Butler’s new film “Den of Thieves” in Atlanta.

How did Butler bulk up for the action-packed movie? “I had to put on like 25 to 30 pounds, and I had to do it kinda quickly," he revealed. "I realized, 'I have to get down to the gym and start eating steaks every night.'”

Gerard’s co-star Pablo Schreiber also needed to beef up. He said, “I prepared for this role by eating a lot [and] working out a lot.”

“Den of Thieves” hits theaters January 19.