Mark Wahlberg packing on 30 pounds within weeks for new role

Mark Wahlberg is relaxing his strict diet and fitness regimen in an effort to pack on 30 pounds (13.6 kilograms) for his next movie.

The Fighter star is currently working on Father Stu, a biopic about boxer-turned-priest Father Stuart Long and the role requires Wahlberg to fatten up once they've wrapped filming on the shoots in the ring.

"After we do the boxing scenes, I get to put on as much weight as possible over the course of the film, so I'm challenging myself to put on 30 pounds in the next six weeks," he told U.S. talk show host Jimmy Kimmel, revealing he will be eating "lots of burgers and lots of buns" to pile on the pounds.

Producers have recruited a "very smart" nutritional expert to help him make the transformation as healthily as possible, but Wahlberg, who is known for his muscly physique, wants to have a little fun with the mission.

"They want me to do it as healthy as possible and I'm like, 'Dude, I've been on such a regimen for so long, I just want to eat everything in sight,'" he shared.

"I want to go to bakeries, I want to go to Denny's (diner), I want to get pancakes, I want to get everything I can possibly get my hands on!" the actor went on.

And Wahlberg, who turns 50 in June, has a calorie-packed fast-food feast planned to get started on the weight gain, which he expects to kick off next week.

"(I'll hopefully start) with a 20-piece chicken nugget and 20-piece hot wings from Kentucky Fried Chicken with a six-pack of beer," he said, quipping: "Why not start with a bang? I might need a porta-potty too, but you know what, I'm ready to go."