Jonah Hill, who often plays the hilarious, best buddy role in comedies, isn't known for sporting a thin frame — but when it came time to prepare for a big screen version of "21 Jump Street," he decided it was time for change. 


The 27-year-old has arriving at various events this month completely transformed, losing an estimated 40 lbs. since December. A source told US Weekly that Hill hired a trainer and nutritionist to assist with the makeover — something the actor admitted on the red carpet was quite the challenge. 


"It’s not fun," he told The LA Times. "I wouldn’t say it’s the most fun endeavor I’ve ever took on in my life — but it’s important. And I’m enjoying it. If I eat something unhealthy now, I kind of feel a little weird and my body hurts."


Hill's transformation reminds me of the dramatic one Drew Carey had last year, dropping 80 lbs. in nine months on a diet rich in veggies, low-fat meals and plenty of exercise. 



"No carbs," Carey told the NY Daily News. "I have cheated a couple times, but basically no carbs, not even a cracker. No bread at all. No pizza, nothing. No corn, no beans, no starches of any kind. Egg whites in the morning or like, Greek yogurt, cut some fruit."


"21 Jump Street," which stars Hill and Channing Tatum, is set for release in 2012.