His recent GQ cover has made it clear: Joseph Gordon-Levitt is kinda jacked. The 31-year-old former "Third Rock from the Sun" kid has grown up to be a bona fide action star, debuting bulging biceps in the much-anticipated Christopher Nolan flick "Dark Knight Rises," which opens in theaters Friday, July 20.
But Gordon-Levitt isn't the only male celebrity to have undergone a transformation, onscreen and off. Check out our gallery of male stars who have gone from lean to mean, including Christian Bale, Mickey Rourke, Zac Efron and more.
Christian Bale should win an Academy Award alone for the number of times he's yo-yo'd for movie roles -- dropping, then regaining, huge amounts of weight and muscle for roles in "The Machinist," "Rescue Dawn," "The Fighter" and the "Batman" series.
Yep, the lanky, little kid from "Third Rock From the Sun" has turned into a bona fide action star who shows off his new biceps in "Dark Knight Rises."
All we have to say about the "Blossom" star's jacked physique -- which he debuted as a <a href="http://www.huffingtonpost.com/2012/06/09/joey-lawrence-chippendales-blossom-star-las-vegas_n_1583518.html" target="_hplink">celebrity Chippendales dancer in June</a> -- is "WHOA!"
The comeback of the decade came when '90s star Mickey Rourke returned to the big screen in Darren Aronofsky's 2008 drama, "The Wrestler."
Hey guy, when did you become so buff?
Zac Efron bulked up when he underwent intense physical training for his role as a U.S. Marine in "The Lucky One." <a href="http://www.huffingtonpost.com/2012/04/13/zac-efron-lucky-one_n_1423678.html" target="_hplink">He told <em>Men's Health</em> in April</a>, "By the end of the movie I didn't recognize myself... You hear about guys like Christian Bale who dive into it and are really able to transform. 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."
Captain America's transformation from a scrawny kid to a pumped-up superhero wasn't a far stretch from Chris Evans' own evolution. The actor said his<a href="http://www.huffingtonpost.com/2011/07/19/chris-evans-talks-captain-america-workout_n_903919.html" target="_hplink"> daily, two-hour workouts were brutal</a>, but that eating to gain weight "sucked more": "You're just so bloated, but you just have to keep consuming protein, so that was tricky."