Mark Wahlberg says eating 11,000 calories to bulk up for a new movie was "fun for about an hour".
The actor piled on around 20 pounds for his role in Stu about a priest who pursues a boxing career, and he admits it was a "hard, physical thing to do" as he had to eat huge meals, even when he wasn't feeling hungry.
He said: "Unfortunately, I had to consume, for two weeks, 7,000 calories, and then for another two weeks, 11,000 calories. And it was fun for about an hour. It's such a hard, physical thing to do.
"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."
Mark admits it has been even more difficult because he is older and his metabolism has slowed.
Speaking on The Tonight Show with Jimmy Fallon, he added: "Once the metabolism starts to slow down, it gets really difficult. I was trying to get this movie made for six years, we only had 30 days to shoot it, and so I wanted to really make it happen.
"I was also crazy to have financed a lot of it myself. I knew I was on a ticking clock on my own dime, and you get things done quickly when that's the case."
Mark's personal chef Lawrence Duran recently revealed the actor starts eating at three in the morning.
Sharing his meal plan, Lawrence said: "So morning usually starts about 3 a.m. and his first breakfast is four eggs – that's the pre-breakfast. Then, he does his workout and then after the workout, which is usually around 5 to 6 o'clock in the morning, we do eight eggs, six strips of bacon, a cup of rice, two tablespoons of olive oil and a protein shake.
"It's his protein-inspired mass weight-gainer to help build on a little more muscle as well. Then, three hours later, we do some kind of ground beef or ground turkey, whether it's been made into a hamburger patty or a meatloaf, with another cup of rice."