Hollywood's 19 Most Dramatic Big-Screen Transformations

Anne Hathaway

The actress, an Oscar contender for her role in the upcoming adaptation of Les Miserables, chopped her locks and lost 25 pounds to play Fantine, a prostitute who is dying of tuberculosis. Of her weight loss -- which reportedly included a cleanse and eating only two small squares of dried oatmeal paste a day -- Hathaway recently told Vogue that it was an intense experience. “I had to be obsessive about it -- the idea was to look near death," she said. "Looking back on the whole experience -- and I don’t judge it in any way -- it was definitely a little nuts."

Robert De Niro

De Niro gained about 60 pounds to play boxer Jake La Motta, the 1949-51 middleweight boxing champion, in Martin Scorsese's 1980 movie Raging Bull. The actor won an Oscar for his dedication.

Cameron Diaz

The actress has said her appearance in 2000's Being John Malkovich -- in which she donned an untamed wig, brown contacts and frumpy clothes -- was so different that even the film crew didn't recognize her on-set. "I didn’t realize that people weren’t going to recognize me until I put the costume on and I stood around talking to people working the production," she has said. "I just assumed they knew it was me, but they thought I was a stranger."

Charlize Theron

The actress won an Oscar for 2003's Monster for her portrayal of real-life serial killer Aileen Wuornos, who was executed in 2002 for murdering six men. For the role, Theron reportedly gained 30 pounds and wore prosthetic teeth.

Christian Bale

The actor, who bulked up to play Batman in Christopher Nolan's Dark Knight trilogy, appeared skeletal in 2004's The Machinist. To play an insomniac, the actor lost roughly 65 pounds and has said he never worried that it might affect his health. "I had what could be called a kind of stupid feeling of invincibility, like, 'Oh I can do it. I can manage it,' " he said.

Tom Hanks

Eight years after Philadelphia, Hanks lost 50 pounds to play a plane-crash survivor in 2000's Cast Away, a role that earned him an Oscar nomination. As Fed Ex worker Chuck Noland, Hanks is first seen out of shape, but production on the movie was stopped for later scenes so that Hanks could diet and whittle his frame and grow a rough beard to portray a desert island dweller.

Tom Hanks

The actor won his first Oscar for 1994's Philadelphia, in which he played AIDS patient Andrew Beckett. He lost a reported 30 pounds for the role. (Two years earlier, Hanks put on a reported 30 pounds for A League of Their Own.)

George Clooney

People's two-time Sexiest Man Alive turned to pasta to gain 35 pounds for 2005's Syriana, in which he played a CIA agent. Because of the weight gain, Clooney suffered a spinal injury while filming a torture scene and ended up in a hospital and bed-ridden for a month. He later called the weight gain "pretty stupid" and said he contemplated suicide after the injury. "I was at a point where I thought, 'I can't exist like this. I can't actually live,'" he has said. The role earned him his first Oscar.

Halle Berry

Berry transformed into a plain Jane for the 2001 movie, which centers on the unlikely relationship that transpires between a racist prison guard (Billy Bob Thornton) and the wife of the last person he executed. Berry made history as the first African-American woman to win a best actress Oscar for her role in the film.

Hilary Swank

The actress won her first Oscar 1999's Boys Don't Cry, in which she played a young female-to-male transgender victim who was killed after his secret was discovered. To prepare for the role, she spent four weeks dressing as a man, lost weight, strapped down her breasts, changed her mannerisms and chopped her hair. ''By the third week of filming I had lost every ounce of my femininity,'' she has said. ''I thought I was never going to be able to find Hilary again. I was totally lost.''

Matthew McConaughey

In the upcoming Dallas Buyers Club, based on a true story, McConaughey plays Ron Woodruff, a Texas electrician diagnosed with AIDS who sought out experimental therapies in the mid-1980s. For the role, the actor aimed to lose 30 pounds. "I should not look healthy by the time I’m doing this," McConaughey said before shooting began.

Jared Leto

Matthew McConaughey's Dallas Buyers Club co-star Leto also underwent a drastic transformation for his role, that of a transsexual woman with AIDS. "I waxed my entire body, including my eyebrows," he said in November. "I've lost a lot of weight because I'm playing a young person with AIDS. It's been challenging but really inspiring, too."

Jared Leto

In addition to his weight loss for Dallas Buyers Club, Leto previously lost 25 pounds for his role as a drug addict in 2000's Requiem for a Dream. But for 2007's Chapter 27, the actor went the other direction, reportedly gaining 60 pounds to play Mark David Chapman, the man who shot and killed John Lennon.

Mariah Carey

The diva de-glammed herself for 2009's Precious, in which she played a dowdy social worker. The singer was reportedly selected for the role at the last minute. "I thought how bold would it be to cast Mariah," director Lee Daniels has said. "If she could dye her hair, put on a wig, take off the makeup, darken under the eyes, I believed she would begin to give me her soul -- and she did."

Matt Damon

For 1996's Courage Under Fire -- one of Damon's first film roles -- he lost somewhere between 40-50 pounds in about 100 days to play a drug-addicted Persian Gulf War veteran. He accomplished that feat by eating only chicken, egg whites, steamed broccoli and baked potatoes and running 12 miles a day. Because of the quick weight loss, Damon suffered some health issues "I went too far," he has said. "I got sick and I wouldn't do that again because it was just too much. At the same time it helped the performance. I didn't have to act at all; I was a wreck. I was getting dizzy spells and hot flashes. I didn't say anything to anyone for a while because I was afraid I might be really ill."

Matt Damon

Like Tom Hanks and Jared Leto, People's Sexiest Man Alive 2007 has both lost and gained weight for his work. In 2009's The Informant! the actor plays an agri-business executive-turned-FBI informant, gaining a reported 30 pounds for the role. “It was very, very easy to gain the weight -- very, very fun,” Damon has said. “I just basically ate everything I could see for a few months.”

Matthew Fox

The Lost alum played a serial killer named "Picasso" in 2012's Alex Cross, starring Tyler Perry as the James Patterson-created character. For the role, Fox shaved his head, embarked on a strict diet of mostly chicken breast, steamed broccoli and protein shakes and did 90-minute circuit-training workouts every day for five months. He lost 44 pounds and said he was shocked when he realized how much his body had transformed. "I never watch my films while we’re making them, so when the images came out on the Internet, I was like, ‘holy s--t,’" he has said. "I could hardly even believe it was me."

Michael Fassbender

The actor lost 42 pounds to star as Irish Republican Army hunger striker Bobby Sands in the 2008 film Hunger. Fassbender put himself on a 900-calorie a day diet for the movie and when that wasn't enough to make him look like he was starving, he began skipping, practicing yoga and walking more than four miles a day.

Renee Zellweger

Zellweger reportedly gained nearly 30 pounds for the 2001 adaptation of Helen Fielding's novel Bridget Jones's Diary, saying she turned to doughnuts and cheese pizzas to help pack on the pounds. The actress, who earned an Oscar nom for the movie, turned around and did it again for the 2004 sequel, Bridget Jones: The Edge of Reason. (A third movie, Bridget Jones's Baby, is in the works.)