Jake Gyllenhaal lost roughly 20 pounds for his role in the crime drama "Nightcrawler." The actor is the latest star to undergo a noticeable physical transformation for a film:
Jason Segel has been working hard to shed weight for his role in the upcoming comedy "Sex Tape," which also stars Cameron Diaz. The 33-year-old actor said that adopting a healthier lifestyle has been the key to his transformation.
Jared Leto recently revealed he shed up to 40 pounds in a stunning transformation as a transsexual woman living with HIV/AIDS in the '80s for "Dallas Buyers Club."
Ashton Kutcher had the good fortune of looking like Steve Jobs' long-lost cousin, so transforming himself into the icon of innovation didn't take much. But it's amazing what the haircut, glasses and beard can do, right?
For 2014's "Guardians of the Galaxy," Chris Pratt gave up beer for six months ... and wound up looking like this.
Matthew McConaughey lost nearly 40 pounds to portray a man diagnosed with HIV/AIDS in the December release "Dallas Buyers Club."
David O. Russell's December release "American Hustle" is set in the '70s, and part of the fun of the film is seeing Bradley Cooper's impressive perm.
Elizabeth Banks' comedic timing is as sharp as ever in "The Hunger Games," but her makeup job is a far cry from how we're used to seeing her.
Daniel Day-Lewis looked presidential enough to appear on currency in 2012's "Lincoln." The actor portrayed the 16th president so thoroughly, he won an Oscar.
In "Looper," Joseph Gordon-Levitt was made up to look more like his co-star, Bruce Willis.
Meryl Streep won a best actress Oscar for her portrayal of British Prime Minister Margaret Thatcher in 2011's "The Iron Lady," and so did members of the makeup team behind her altered appearance. They told Entertainment Weekly they pulled it off by working around Streep's natural facial elements, such as her eyebrows.
50 Cent had fans worried that he was truly ill when images surfaced of his role as a man suffering from cancer in "All Things Fall Apart."
While we've seen him become extremely thin to play a character, Leto has also gone in the other direction. For "Chapter 27," he packed on 60 pounds to portray Mark David Chapman.
Even if you don't remember 2008's "Tropic Thunder," you likely recall that Robert Downey Jr. was in blackface for his role. The controversial makeup choice was reflective of the lengths that Downey's method actor character, Kirk Lazarus, would go to portray a Vietnam War sergeant who was initially written as African-American.
Charlize Theron's transformation into serial killer Aileen Wuomos was amazing -- she also won the best actress Oscar for 2003's "Monster." Gaining weight not only helped Theron fit the part, but she also wore makeup to create a less perfect complexion and a set of crooked, yellowed teeth.
Nicole Kidman nabbed a best actress Oscar for her portrayal of Virginia Woolf in 2002's "The Hours." But the makeup job that changed her appearance -- aided greatly by a prosthetic nose that stirred debate -- didn't receive a nod.
For his role as a man who aged in reverse in "The Curious Case of Benjamin Button," Brad Pitt "had to endure the most complicated and time-consuming makeup effects," sometimes spending five hours at a time in the makeup chair, producer Frank Marshall told Variety in 2008.
Christian Bale's disturbingly gaunt frame in "The Machinist" is a legendary tale of going all out for a character. The actor famously dropped 63 pounds for the part by sticking to a diet of coffee, cigarettes and an apple a day.
Heath Ledger's Joker was thrillingly unhinged in 2008's "The Dark Knight," and the makeup job was part of the package. Both the actor and the makeup team were nominated for Oscars, but it was Ledger who was honored posthumously with the award.
When she landed the part of Lisbeth Salander in 2011's "The Girl With the Dragon Tattoo," fresh-faced Rooney Mara got a severe haircut in an inky hue, bleached her brows and pierced her nose, lip, eyebrow and nipple.
Critics heaped praise on Marion Cotillard's award-winning portrayal of French icon Edith Piaf in 2007's "La Vie en Rose." The physical part of her transformation into Piaf took patience, with Cotillard's role demanding five hours in a makeup chair.
Eddie Murphy has a knack for portraying multiple characters in the same film, and in 1988's "Coming to America," he played Prince Akeem and comedic barbershop gentleman Saul (pictured, right) among others. Makeup artist Rick Baker earned an Oscar nod for his work.
Julianne Moore was tasked with convincingly portraying Sarah Palin in HBO's 2012 movie "Game Change" and implicit in doing so was looking the part. Moore pulled it off, picking up an Emmy in the process. Among those she thanked? Her hair and makeup team, of course.
The makeover for Eric Stoltz in 1985's "Mask" was astounding as Stoltz portrayed "Rocky" Dennis, a boy trying to live a normal life with the disorder lionitis. The transformation picked up an Oscar for best makeup.
- Jake Gyllenhaal has lost a little more than 20 pounds
- The actor is getting into character for "Nightcrawler"
- In the movie, he says he's playing someone who's "hungry literally and figuratively"
(CNN) -- It looks like 2013 is going to be the year of the severe physical transformations for actors.
For his upcoming project "Nightcrawler," Jake Gyllenhaal has not only grown his hair long enough to sport a "man bun," but he's also become remarkably thin.
"(I've lost) probably a little over 20 pounds so," Gyllenhaal told CNN at this week's Hollywood Film Awards. "I'm playing a character that is hungry literally and figuratively."
Written and directed by Dan Gilroy, "Nightcrawler" is a crime drama that stars Gyllenhaal as an ambitious young man who becomes enmeshed in Los Angeles' underground scene of crime journalism.
"He is very driven," Gyllenhaal says of his character, "and doesn't have very much time to think about anything (else). It's an amazing script."
The 32-year-old isn't the only star who felt the need to transform himself physically to get into character. "How I Met Your Mother" star Jason Segel has become almost unrecognizable after slimming down for the comedy "Sex Tape," and both Matthew McConaughey and Jared Leto became severely thin for "Dallas Buyers Club."
Not everyone loses weight for their characters though. In David O. Russell's anticipated December release, "American Hustle," Christian Bale -- already no stranger to transforming himself physically -- packed on some pounds.
CNN's KJ Matthews contributed to this report.
