Mark Wahlberg completely changed his look to fit the role of Jim Bennett in his new film The Gambler, but he was miserable in the process.

The film's director Rupert Wyatt told Wahlberg to lose weight in order to properly portray a college professor with a serious gambling addiction.

"Rupert was a little bit freaked out when he saw me," Wahlberg told Yahoo. "He said, 'I don't really think this [character] is a guy who focuses too much on fitness or nutrition.'"

In turn, the 43-year-old had to lose his muscles and get as thin as he could. Wahlberg said he lost 60 pounds and dropped down to 137 on the scale. To shed the weight for the remake of the 1974 drama, Wahlberg went on a strict liquid diet and jumped rope for two or three hours a day.

"I became a miserable prick," the actor said. "I'm a huge foodie. I'd have a dinner meeting with a group, and just watch them eat. I had a major, major craving for anything and everything. I would go to places and look at the menu. My wife would be like, 'Why are you torturing yourself?'"

However, the Boston native quickly gained back the weight to shoot additional footage for Michael Bay's latest installment of the Transformers.

"When I finally was able to eat, I rushed out to have a huge breakfast," Wahlberg said. "Eggs over easy, corned beef hash, pancakes, toast, home fries, real bacon. The English muffin that came, it was only, like, lightly toasted. I said, 'Dude, I've been waiting for five months for this. You got to take it back, and it's got to be golden brown.' But then I ate it, and I ate all that food, I ate every last little crumb. And then I felt like sh*t."

The Gambler opens in limited theaters Dec. 19 and will expand to more theaters on Jan. 1, 2015.

View the trailer below:

Tags: Mark Wahlberg The Gambler