Nick Jonas looks unrecognizable after gaining 15 pounds of muscle to play a mixed martial arts (MMA) fighter in the DirectTV drama series, "Kingdom" (see trailer above).
"I gained about 15 pounds of muscle for the role," Jonas told E! "I really wanted to look like an animal who internalizes a lot, but when he's in the cage and he's fighting that's when you see this kind of animalistic mentality that he has."
Nick said his brothers, Joe and Kevin (of the Jonas Brothers band), joked about his buff physique. "They were calling me the Hulk and they were poking fun at me a little bit," said Nick, who also shaved his head for the role.
The usually lanky Nick has since lost seven to 10 pounds, and said he feels better at his normal weight. Jonas said he followed a low-carb, high-protein diet and did lots of strength-training, MMA workouts and circuit-training to bulk up.
Diagnosed With Type 1 Diabetes at Age 13
While actors routinely gain or lose weight for acting roles, Jonas had to be especially careful with his diet and exercise routine because he was diagnosed with type 1 diabetes in 2005 at the age of 13.
Nick said his diabetes forced him to adopt a healthy and active lifestyle. Jonas' girlfriend, Miss Universe 2012 Olivia Culpo, is also a fitness fanatic.
Jonas said he follows a low-carb diet to keep his blood sugar stable. "[I eat] a lot of lean protein, and I’ve cut out most carbs," he told Men's Fitness. Jonas said rigorous exercise impacts his blood sugar, so he has to be mindful to monitor his blood sugar throughout the day.
"When I work out, my blood sugar goes up," he said. "But then about an hour and a half later it drops down low. So, post-workout I would have to not only have protein to rebuild muscle but also carbs to sustain my blood sugar. So when I cut a lot of carbs out of my diet, I had to be conscious of that."
Halle Berry Also Has Type 1 Diabetes
Jonas isn't the only celebrity who has diabetes. Actress Halle Berry, who was diagnosed with type 1 diabetes in 1989, follows a low-carb, sugar-free diet for diabetics that features non-starchy vegetables and high-quality proteins.
Despite her diabetes, Berry lost weight quickly after giving birth to her second child (son Maceo) in October 2013. Halle credited a low-carb, sugar-free diet and cross-training workouts for her stunning weight loss.
The lithe 5-foot-6 brunette stunner typically works out for 90 minutes, five days a week, doing a routine that combines cardio exercise with cross-training. Berry said she dislikes working out, but does it to manage her diabetes.
"I do not love to work out," she told Vogue. "But if I stick to exercising every day and put the right things in my mouth, then my diabetes just stays in check."
Halle is married to French actor Olivier Martinez. She has a six-year-old, daughter, Nahla, with Canadian model Gabriel Aubry.