Out with the purity ring, in with the fighting ring. Former Disney pop star Nick Jonas is looking to shed his squeaky-clean reputation for an upcoming television role as an MMA fighter. Whereas most teen idols fade away quickly and make TMZ headlines for odd and addictive behavior, the Jonas Brother wants you to know he won’t be taking your sh*t.

In a new interview with Details magazine, Jonas outlines his transformation from skinny kid to real contender for the upcoming series Kingdom, about a young kid and a former MMA champ trying to make it in the fighting world.

“I had about six weeks to put on 12 to 15 pounds of muscle before filming started,” he says, mostly crediting his diet. “Breakfast was usually an omelet with veggies and cashew cheese, a turkey-meat patty, and some fruit; lunch and dinner would be lean protein, veggies, and nuts; snacks consisted of things like snap peas with peanut sauce.”

Jonas, a Type 1 diabetic, navigated his diet carefully, putting down 4,200 calories a day to bulk in time for shooting. As for the gym, he hit the weights hard but isn’t a fan.

“I’m trying to incorporate more cardio. But I hate going to the gym. I think everybody hates cardio to some degree. I’m not the kind of person who wakes up in the morning and can’t wait to work out. I kind of dread it, actually. I see it as a necessary evil.”

Check out a preview of the show here: