"Everything," the star, who plays champion boxer Micky Ward in the film, told PEOPLE at Friday night's Cinema Society premiere in New York City. "I just became obsessed with chocolate-chip cookies and stuff that I never really had any interest in eating [before]."
But his wife, Rhea Durham, had some issues with his post-film indulging.
"She said, 'You might as well take care of yourself,'" Wahlberg, 39, says. "But I needed a break from it. Certainly four-and-a-half years was very draining. I needed that time off, and now I need to get back in there."