Zac Efron has always been a cutie, but it was his recent role as a marine in 2012’s The Lucky One that had us saying, wowza! With those bulging biceps and that chiseled chest, Efron suddenly transformed from super cute to super hot. So how’d he do it? The 25-year-old actor, who was 145 pounds when he began training for the film, packed on more than 18 pounds of muscle to his slight frame by eating six to eight times a day, protein shakes between meals, and lifting weights like he’d never lifted before. “By the end of the movie I didn’t recognize myself,” Efron told Men’s Health. “I’ve always wondered if I had the willpower to actually do it. And I'll always have pride around the sense that I can.”