By Emily Feimster and Stacy Jenel Smith There are big bucks being made in Hollywood but playing the parts is not as easy at it looks. Many actors take extreme measures getting ready for a role. Some of these transformations and techniques have turned little-known actors into megastars.A perfect example is Adrien Brody. To get closer to Wladyslaw Szpilman, the real-life concert pianist and Warsaw Ghetto survivor he portrayed to Oscar-winning perfection in "The Pianist," Brody practiced the piano for four hours a day, until he was able to play specific passages by Chopin. Then, to get into the mindset of a man who had lost his family and his home, "I gave up my apartment, I sold my car, I disconnected the phones, and I left," he told the BBC. "I took two bags and my keyboard and moved to Europe." And he crash dieted for six weeks. At his lightest he reportedly had a mere 130 lbs. on his 6-foot-5 inch frame.

"I couldn't have acted that without knowing it," he explained. "I've experienced loss, I've experienced sadness in my life, but I didn't know the desperation that comes with hunger."

Nothing creates Oscar buzz like gaining and shedding pounds to fit into a role. To play a man dying with AIDS, actor Tom Hanks lost 30 lbs for "Philadelphia." Did we mention that he won an Academy Award for it? He then gained 50 lbs for his role in "Cast Away" only to have to lose it all months later. Renee Zellweger reached superstardom after gaining 20 lbs for her role in "Bridget Jones's Diary" as did recent Oscar winner Charlize Theron, who put on 30 lbs to play a killer in "Monster." Matt Damon dropped a whopping 40 lbs for his role as a drug-addicted Gulf War vet in "Courage Under Fire." Let's not forget Robert De Niro who held the world record for Most Weight Gained for a movie by gaining over 60 pounds for his role in "Raging Bull." A once scrawny Will Smith spent months bulking up for his Oscar-nominated portrayal of Muhammad Ali but quickly had to hit the treadmill running "almost 40 miles a week" to reprise his role in "MIB II."

Tobey Maguire, who'd buffed up to play "Spider-Man," says he took it as a personal challenge to alter his body to play jockey Red Pollard in "Seabiscuit." His regimen included 16 workouts a week and a diet. "His body fat got down to something like six percent, which is borderline unnatural," according to filmmaker Gary Ross.

The only weight Gwyneth Paltrow wants to put on is when being pregnant. She kept her slender frame in "Shallow Hal" by wearing a 200 pound latex "fat" suit for her role as an obese woman. As part of her research, she wore the suit to a bar where people refused to make eye contact with her and treated her rudely. Paltrow said the experience made her saddened by the injustice faced by overweight people. Surely the heavy folks feel better now knowing that the poundless Paltrow feels their pain.

A not so well-known Hilary Swank cut off all of her hair and lived as a boy for one month to prepare her for her role in "Boys Don't Cry." At the time, she only made $75 a day but after taking home Mr. Oscar, she purchased a $4 million home with husband Chad Lowe. Now there's a transformation that paid off.

Other famous actors have done their homework as well. "Against the Ropes" star Meg Ryan took three weeks of boxing lessons to understand the sport and the terms her character would use. Matt Damon stepped it up again by bartending in Tennessee for free to perfect his Southern accent for his role in "The Rainmaker." Keanu Reeves learned over 200 martial arts moves for "The Matrix Reloaded" and Zellweger endured a grueling regime of vocal coaching and dance training for 10 months to get up to professional standard for "Chicago."

Then there are some of Hollywood's most infamous actors who do whatever it takes to get into character. While playing a NYC cop in "Serpico," Al Pacino was so much into character that he actually pulled over and threatened to arrest a truck driver for exhaust pollution. Nicolas Cage's one-time passion for method acting reached a personal limit when he smashed a street-vendor's remote-control car to achieve the sense of rage needed for his gangster character in "The Cotton Club." Now that wasn't necessary.

There seems to be no limit as to what these people will put themselves through to make our movie-going experiences as realistic and memorable as possible. Well, those $10-$20 million salaries they're making probably don't hurt either!