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Mark Wahlberg on eating more than 11,000 calories for new role: 'It was not fun'

The actor discussed his weight gain for "Stu" on "The Tonight Show."

Mark Wahlberg shared details about his recent weight gain for a role as a boxer-turned-priest in "Stu."

The 50-year-old actor told Jimmy Fallon on "The Tonight Show" Thursday that he was eating every three hours.

"Unfortunately, I had to consume for two weeks 7,000 calories and then for another two weeks 11,000 calories," the "The Departed" star said. "It was fun for about an hour."

"It's such a hard, physical thing to do," he added. "Losing weight, you just kind of tough it out — you just don't eat, and exercise. And this, even when you're full, I would wake up after a meal and have another meal. I was eating every three hours. It was not fun."

Wahlberg posted his transformation on Instagram with the caption "From left photo 3 weeks ago to this, now. Thanks to @chef_lawrence_d cooking."

The photo received several positive comments including "I think you look just as good on the left as you do on the right," from Dr. Oz.

"And it looks just as hot in person baby," Wahlberg's wife, Rhea Durham, commented in support.

"Yo," Mario Lopez chimed in. "You wear mad chubby well homie!"

Fallon asked Wahlberg if it's harder to gain and lose weight now that he is 50.

"Absolutely. Once the metabolism slows down, it gets really difficult," he responded "I'd been trying to get this movie made for three years. We only had 30 days to shoot it. And so I wanted to really make it happen."

Wahlberg was on "Jimmy Kimmel Live" in April before he began "packing on the pounds."

"After the boxing scenes, I get to put on as much weight as possible over the course of the film," Wahlberg told Kimmel. "So I'm challenging myself to put on 30 pounds in the next six weeks."

Wahlberg also discussed his new movie "Joe Bell" — which is based on a true story — with Fallon.

"A dad is basically going on a journey from La Grande, Oregon, to NYC where his son always wanted to live. And he's talking to anybody and everybody that he can meet, people that he confronts about intolerance and bullying. He's trying to raise awareness for his son."

Wahlberg noted that reading the script as a dad, he was "very moved by it."

"It's such an important story to be told," he added.