Bulkier Actor/Actresses

Jackman, who began training a full year before shooting began, would often begin his day at 4 a.m. with a breakfast of a whole chicken (tasty!) or egg whites and toast (no butter or jam and any other yummy toppings, of course). "[I] wiped out entire gene pools of chickens," he joked of his copious protein consumption. "To any vegetarians out there, I really apologize." The reigning Sexiest Man Alive ate every three hours and put away an estimated 4,500 calories a day. His disciplined diet was combined with explosive-impact weight training (he could bench press an impressive 300 to 320 pounds), all of which turned his body into a bulging mass of eye-popping pecs and bazooka-sized guns.

Talk about commitment to physical fitness. Sarah Connor didn't let being locked in the loony bin stop her from shaping up for Armageddon, as evidenced by the film's establishing shot of her doing pull-ups on an upturned bed frame, her mighty biceps glistening with sweat. To get into mesomorphic mama-bear-meets-warrior mode, Hamilton first had to say "hasta la vista" to her post-pregnancy pounds. Three months before shooting began, she started six-day-a-week, three-hour-a-day training sessions that had her sweating from running, swimming, biking, stair-climbing, lunges, weight lifting, judo, and some quality mini-trampoline time. She dropped a dozen pounds while adding enough muscle mass to pump a shotgun with one arm, a feat helped along by a rigid diet consisting of a lot of chicken and salads (no dressing, natch). "You couldn't stop me from working out," Hamilton told MTV News. "I remember I had a tiny piece of cheese one day and thought I had blown everything. It was literally the only cheese I had in nine months."

To achieve his character's physical perfection, Bale adopted what he described as an "incredibly boring" diet, shoveling down plenty of protein and vegetables and gorging on carbs such as bread, rice and pasta in order to build body mass. His exhausting workout regimen ranged from running and weight training to yoga, boxing and stretching. Not that the actor would recommend trying to duplicate Bateman's chiseled physique. "You can't have a body like that if you want to have a life," said Bale, "or any meaningful relationships."

Demi prepared for the grueling on-screen physical trials (running obstacle courses, crawling through mud and sand, rolling oil drums, carrying life rafts, and enduring push-ups in the freezing surf) by going through her own real-life version of SEAL Hell Week. Her boot camp-inspired daily routine consisted of running, swimming, obstacle-course tests and endless push-ups, sit-ups and squats.

Unlike Pitt's lean cut of bruised beefcake look from "Fight Club" five years before, his brawny bod in "Troy" is a gift straight from Mount Olympus. The A-lister reportedly requested a toga-dropping nude scene in the sprawling flick, which seems like a reasonable request considering he was feeling the burn six days a week for eight months leading up to the start of production. The star achieved Hellenic hunkiness with weights (a gym and trainer came with him on location to Malta and Mexico), yoga, running and sword training, along with balance training on a seesaw board, medicine ball hoisting and various one-legged exercises. In between, Brad refreshed with vitamin-rich protein shakes and daily massages.

Smith went from slim to solid by gaining more than 30 pounds of muscle over the course of a year. He got ring-ready by kick-starting his day with a run before segueing into boxing practice and weight training (at his peak, he was able to bench press 300 pounds). By the time cameras rolled, he had completed his metamorphosis into a well-built, Ali-like wall of 220 pounds.

"Only the hard and only the strong may call themselves Spartans." So says Leonidas, a line Butler apparently took to heart by training unremittingly for four months. Not only did he work with both a Venezuelan bodybuilder ("I wanted to look really strong," Butler told Men's Health), but he also got into character both physically and mentally with something called the 300-rep Spartan workout, which required him to do -- without a rest -- 50 pull-ups (25 at a time), 50 push-ups, 50 dead-lifts (135 pounds at a time), 50 jumps on a 24-inch box, 50 floor-wipers (lie on your back, lift a barbell and touch it on the left and right with your legs) and 50 "single-arm clean-and-presses using a 36-pound kettle bell." We have no idea what that last one is, but it sure sounds backbreaking. Toss in some tire flipping and gymnastics-inspired ring-training, and Butler ended up with a powerful body that was royally ripped.

It takes a lot of work to fill out 007's Speedo and tuxedo. For six months, Craig spent six days a week on an exhausting regimen that ranged from pull-ups and push-ups to squats and dips. He also spent a lot of time with a dumbbell in his hand, with endless lateral raises responsible for those sigh-worthy broad shoulders. But the tough training was necessary to play the lady-killer with a license to kill. "I had black eyes, I had cuts, I was bruised, I had muscle strains, and I took a lot of painkillers," said the actor. "But it was part of the job."

The big moment when Peter takes off his shirt and we see that his once-puny body is now bulging with muscles was accomplished through six months of six-day-a-week training sessions, some lasting up to four hours. The actor's intensive workouts focused on weight-lifting, running, cycling, yoga, gymnastics, and martial arts. Maguire, a vegetarian, also partnered with a nutritionist and ate four to six times a day to bulk up.

Underneath that iron suit, Tony Stark was rocking some abs and buns of steel. Downey got buff for what would be his comeback role by undertaking strenuous daily workouts to pack on more than 20 pounds of muscle in five months. The catch? The Iron Man suit couldn't be altered, so the star had to be careful not to get too beefy. His trainer, Brad Bose, used various exercise machines (Jacob's Ladder, The Pineapple) to work every muscle group and build strength but not bulk, which fit in with his superpower-free character. "They wanted someone unique," explained Bose. "His character is an alcoholic and a womanizer, and he's an arms dealer. They didn't want a six-pack or bulging muscles, but they wanted to see that he had the power to forge iron."

Verisimilitude-devoted De Niro, who had previously put on 60 pounds for "Raging Bull" and 30 pounds for "The Untouchables," whittled his body fat down to just four percent to play Cady, gaining muscle with a combination of weight-lifting and a carb-crammed diet. "I feel if you're going to do certain parts," the actor told Time, "you really have to commit to them all the way to make them special."

Audiences won't get to see Gyllenhaal in his pumped-up state until May 2010, but, judging by the trailer, the wait will be worth it. "I guess I've gotten buff," he downplayed to "Entertainment Tonight" during filming. "There's a lot of acrobatics in the movie -- a lot of running up walls, and jumping on things and parkour [basically, running full-speed at an object and bouncing off it]. So it requires muscularity, but it requires a lot of aerobic ability, too." The actor's training reportedly included wearing a 20-pound jacket while running and doing uphill sprints followed by sit-ups upon reaching the top (we got winded just typing that).

Faced with his own moment of career redemption, Rourke was willing to do whatever it took to sell the role. That included performing many of his own stunts, from the rope dives to slicing open his much-altered face with a razor blade. Mickey went for maximum authenticity by spending months getting put through his paces with a former Israeli cage fighter and supplementing breakfast, lunch and dinner with four other meals, all of which helped him put on 46 pounds of muscle. As for whether he got deep enough into character to add heft with steroids or human growth hormones, he coyly told Men's Journal, "When I'm a wrestler, I behave like a wrestler."

Before "Blade," Reynolds was better known for his frat boyish charms in "Van Wilder" than his body, and he made a beeline for the gym as soon as he landed the vampire flick. He filled out by gaining 25 pounds of muscle and got chiseled by getting down to just 3 percent body fat. Every day, he did a dizzying 500-1,000 sit-ups, along with weight training and a diet heavy on oatmeal, protein bars, chicken and eggs. "All told, it was about seven months of just every day living like a complete fool, living in the gym and eating a diet that is scientific basically," explained the actor, whose reshaped body probably didn't hurt when he was wooing now-wife Scarlett Johansson (or when he was preparing for "Wolverine"). "I put on a lot of weight. I ate every two hours. All day, every day. I'd even wake up in the middle of the night and eat," he said. "The biggest challenge was having to gain all that weight and spend all my time in the gym. That was something that I'd never done before. That nearly broke me."

Travolta was able to carve his body into primo dancer condition thanks to the film's director, Sylvester Stallone, a guy who knows muscles. Sly helped devise a plan that had Travolta working out six days a week for nearly five months (14- and 16-hour gym days were not uncommon). The actor lost 20 pounds and gained a sleek, muscular build that he called "more contemporary and sexier."