Getting into character for a movie role isn't just about putting on a costume and memorizing lines. Celebrities sometimes need to gain or lose a couple of pounds too--or maybe 40 to 50 of them!

Matthew McConaughey recently lost 30 pounds to play the role of a character with HIV in the upcoming movie The Dallas Buyers Club, but that's not out of the ordinary in Hollywood. A-listers are often asked to go the extra mile for their mega-paychecks by gaining or losing crazy amounts of weights in a short period of time, which leads to a whole bunch of methods no doctor would ever advise! From Beyonce to Ryan Gosling, check out the 14 craziest celebrity weight losses and gains of all time!

1. Charlize Theron

Charlize Theron weight gain

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Weight gained: 30 pounds

Role: Aileen Wuornos in Monster

How she did it: “I first began stuffing myself with Krispy Kreme doughnuts, but after a while I got sick of them,” said Charlize. “I love potato chips, so that was a good thing for me. I’m a salty girl so I had my secret stash with me of potato chips at all times.”

Despite Charlize's less than healthy methods of gaining weight, putting her body through that torment paid off. She ended up winning the Oscar for Best Actress for her work in the film.

2. Rob Mcelhenney

Rob Mcelhenney weight gain

 

Weight gained: 50 pounds

Role: Mac on FX show It's Always Sunny In Philadelphia

How he did it: Five meals per day that each totalled 1,000 calories. "When you're four months in it and you have to muscle down 1,000 calories for the third time or fourth time in a day and you have to either eat three chicken breasts, two cups of rice and two cups of vegetables -- or one Big Mac -- you start to see the Big Mac and realize it's a lot easier to get down," said Rob.

Believe it or not, Rob requested to gain the big 5-0 because he thought it would make his character on the show funnier. He also asked his fellow castmates to join him in the weight gain, but they all declined. We wonder why!

3. Jared Leto

Jared Leto weight gain

Weight gained: 67 pounds

Role: John Lennon assasin Mark David Chapman in Chapter 27

How he did it: Microwaving pints of chocolate Haagen Dazs and drinking them. Sometimes he would throw olive oil and soy sauce into the mixture to get more bloated.

Know what sucks more than gaining 67 pounds for a role? Nobody even noticing because the film couldn't draw flies! The film premiered to terrible reviews and grossed just $56,215 in North America. 

4. Russell Crowe

Russell Crowe weight gain

Weight gained: 63 pounds

Role: Spy Ed Hoffman in Body of Lies

How he did it: Eating cheeseburgers for breakfast. Literally! And an excess amount of Sprinkles cupcakes.

We hate to say it, but Russell was never really in a position to gain any pounds, let alone 63 of them. Luckily, he quickly shed the weight immediately after filming.

5. Ryan Gosling

Ryan Gosling weight gain

Weight gained: 60 pounds (from 150 to 210)

Role: Grieving father in The Lovely Bones

How he did it: "I was melting Haagen Dazs and drinking it when I was thirsty," joked Ryan.

The worst part about Ryan's weight gain was that after being asked to gain the weight, they ended up never using him in the film! His role ended up being given to Mark Wahlberg and Ryan quickly returned back to his normally hunky frame.

6. Renee Zellwegger

Renee Zellwegger weight gain

Weight gained: 28 pounds

Role: Bridge Jones in Bridget Jones's Diary

How she did it: According to businessinsider.com, she kept a strict 4,000 calorie per day diet.

This is one of the few times when moviegoers cheered at one of their favorite stars putting on an excessive amount of weight. Her role was universally popular in theaters and even ended up leading to an Oscar nomination.

7. George Clooney

George Clooney weight gain

Weight gained: 30 pounds

Role: A terrorist in Syriana

How he did it: A heavily pasta-based diet and cutting out all forms of exercise

Take note: A lack of exercise can lead to depression. That's exactly what happened to George on set when he was forced to remove working out from his schedule in order to gain the weight.

8. Matt Damon

Matt Damon weight gain

Weight gained: 30 pounds

Role: Mark Whitacre in The Informant!

How he did it: Dark beer, Doritos and McDonald's as in-between meals while on set

Matt has swung on both sides of the weight loss spectrum for movie roles. He also lost 40 pounds for his role in the 1996 film Courage Under Fire.

9. Christian Bale

Christian Bale Weight Loss

Weight lost: 63 pounds

Role: Machinist and chronic insomniac Trevr Reznik in The Machinist

How he did it: Having only an apple and a cup of coffee every day for several months

We're guessing Christian has a masochistic streak. In addition to his crazy weight loss for this film, he also dropped his weight down to 121 pounds for his role in The Fighter

10. Tom Hanks

Tom Hanks weight loss

Weight lost: 50 pounds

Role: Analyst Chuck Noland in Cast Away

How he did it: Extremely strict dieting

Tom is a pro at gaining and losing weight at this point. He gained 30 pounds to play Jimmy Dugan in 1992's A League of Their Own. and also lost 26 pounds to play AIDS-stricken Andrew Beckett in Philadelphia.

11. Beyonce

Beyonce weight loss

Weight lost: 20 pounds

Role: Back-up singer Deena Jones in Dreamgirls

How she did it: Subsisting mainly on water with cayenne pepper.

We prefer Beyonce with curves rather than without, but she looked damn good in this movie! She also went to the other extreme by gaining 15 pounds to play Etta James in Cadillac Records.

12. Natalie Portman

Natalie Portman weight loss


Weight lost: 20 pounds

Role: Nina Sayers/The Swan Queen in The Swan

How she did it: Working out five hours per day, seven days a week.

Although working out five hours per day is pretty extreme, we have to give her props for having the "healthiest" method for gaining or losing weight on this list!

13. 50 Cent

50 Cent weight loss

Weight lost: 54 pounds (from 214 to 160)

Role: An athlete diagnosed with cancer in Things Fall Apart

How he did it: An entirely liquid diet for nine weeks

The normally ripped 50 caused a sensation on the internet when he posted this emaciated-looking photo of himself on Twitter, prompting a brief round of rumors that he was dying!

14. Anne Hathaway

Anne Hathaway weight loss

Weight lost: 16 pounds

Role: Factory worker Fantine in Les Miserables

How she did it: Limiting herself to 500 calories per day

Anne doesn't exactly have much weight to lose to begin with, so her 16 pound drop was so dramatic that a doctor was hired to keep an eye on her!

What do you think is the most dramatic weight loss celebrity weight loss/gain?

Photos courtesy of Fame Flynet, Getty Images, FX, 20th Century Fox, Paramount Pictures, Universal Pictures, United Artists, Castle Rock Entertainment and Warner Bros Pictures