Mark Wahlberg has stunned fans by showing off his dramatic physical transformation for a movie role on Instagram.

The 49-year-old action star, who is known for his gruelling workout routine, which involves waking up at 2.30am, has been gaining weight in an effort to put on 30 pounds (13.6 kilograms) in the space of six weeks to play a boxer-turned-priest in Father Stu.

And after completing filming on the boxing scenes, Wahlberg began his weight-gain journey, and shared his progress after three weeks on Instagram on Monday, with him sharing side-by-side before and after comparison photos of him looking ripped and chiselled as the boxer and looking chubby while relaxing in bed.

In the caption, he thanked his chef Lawrence Duran for providing the food for his weight-gain project, writing, “From left photo 3 weeks ago to this, now. Thanks to @chef_lawrence_d cooking.”

In the comments, his wife Rhea Durham wrote, “And it looks just as hot in person baby,” with a heart emoji.

The Departed star said during a recent appearance on Jimmy Kimmel Live! that he was excited to indulge in unhealthy food to help him pile on the pounds after spending years on a strict fitness and diet regime.

“After we do the boxing scenes, I get to put on as much weight as possible over the course of the film,” he said. “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.

“I want to go to bakeries. I want to go to Denny’s. I want to get pancakes. I want to get everything I can possibly get my hands on.”

Wahlberg has been trying to get a biopic about Father Stuart Long made for years. Mel Gibson is co-starring as Long’s father, while Gibson’s longtime partner Rosalind Ross has written the script and is making her directorial debut.

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