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Mark Wahlberg -

Mark Wahlberg really committed himself to his role as Father Stuart Long, the real-life boxer-turned-priest for his 2022 film 'Father Stu.' He told ET he had to put on about 30 lbs (13.6 kg) in six weeks for the role, and detailed the stomach-turning lengths he went to do it. "I started with 7,000 calories for the first two weeks and then 11,000 calories for the final four weeks,” Wahlberg said. “None of it was fun, except for the first meal was amazing, because I hadn’t eaten anything up until that point. But after that, when you’re already full and you have to eat again, and at my age it’s just not a healthy thing to do, to try to put on that kind of weight in that amount of time.” The 50-year-old tried to do it the healthiest way, which involved maintaining a workout schedule but also drinking olive oil by the glass. "The first two weeks were high proteins. The second two weeks were a lot of carbs. The last two weeks starches, and then sodium, just to kind of get as bloated as possible. So not a lot of fun," he shared. 

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Joaquin Phoenix -

Joaquin Phoenix is one of those actors who isn't afraid to push himself to extremes to give the best possible performance. He looked gaunt and terrifying when he took on the role of Joker, completely changing his gait and the way he carried himself. Not to mention the fact that the lost 52 pounds (24 kg) to achieve the director's ideal image of the character. Phoenix has since gone in the other direction for his latest movie, 'Disappointment Blvd.' He was spotted on set looking like a completely different person. He has gained quite a bit of weight and is rocking grey hair.  When he became extremely thin for 'Joker' (2019), Phoenix shared that he enjoyed the physical aspect but said that the weight loss had a severe impact on his mental health. 

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George Clooney -

For his film, 'The Midnight Sky,' George Clooney shed nearly 28 lbs (13 kg) to play the role of an astronomer who survives an apocalyptic event, The Mirror reports. Despite his incredible dedication, losing the weight so fast meant he compromised his health, and four days before he was due on set, he was rushed to the hospital with stomach pains eventually diagnosed as pancreatitis. He was forced to spend weeks recovering, "But it certainly helped with the character," he said. 

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50 Cent - According to the Daily Mail the actor lost almost 25 kilos to play the role of a young man with cancer in 'All Things Fall Apart' (2011).

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Hilary Swank - To play the role of a boxer in 'Million Dollar Baby' (2004), Swank underwent an intense training program to attain an athletic physique, gaining nine kilos in muscle tissue, according to Exercise Reports.

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George Clooney - To play the main role in 'Syriana' (2005), the actor put on 14 kilos, as reported by Female First.

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Jared Leto - CNN said that the actor had to lose between 14 to 18 kilos for his part in 'Dallas Buyers Club' (2013).

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Matthew McConaughey - To play the role which won him an Oscar in 'Dallas Buyers Club' (2013), the actor reportedly lost about 21 kilos, according to the BBC.

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Chris Hemsworth -

Famous for his role as Thor, the actor had to lose roughly 14 kilos when he played James Hunt, a British racing driver, in 'Rush' (2013), according to Hollywood Life.

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Jake Gyllenhaal - Business Insider reported that the actor lost 14 kilos for his role in 'Nightcrawler' (2014).

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Jake Gyllenhaal - The actor played a boxer in 'Southpaw' (2015), and underwent intensive training in order to gain seven kilos of muscle in just six months, according to the Daily Mail.

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Chris Pratt -

Used to play the slightly overweight Andy in the series 'Parks and Recreation,' Pratt followed an intense diet and training routine to get this body for 'Guardians of the Galaxy' (2014). According to Men's Fitness he lost about 27 kilos in six months.

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Jared Leto - The Hollywood Reporter said that the actor had had to put on 30 kilos for his part in the movie 'Chapter 27' (2007).

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Tom Hanks -

Hanks lost approximately 23 kilos when he acted in 'Cast Away' (2000), according to The Telegraph.

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Robert De Niro - For one of the most iconic roles of his career, the actor underwent two transformations. To play Jake La Motta, in 'Raging Bull' (1980), the actor trained for a year, just like La Motta, according to Men's Fitness.

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Robert De Niro - Later on in the movie, De Niro had to gain 27 kilos, according to The Telegraph, after his character underwent a complete physical transformation.

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Bradley Cooper - To play the part of Chris Kyle in 'American Sniper' (2014), the actor underwent training to gain seven kilos in muscle, according to Men's Health.

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Jason Segel - The Daily Mail reported that Segel had lost almost 16 kilos to play one of the main roles in 'The Five-Year Engagement' (2012).

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Natalie Portman - The actress reportedly lost nine kilos for her starring role in 'Black Swan' (2010), according to E News.

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Margot Robbie - For the role of Tonya Harding in the movie 'I, Tonya' (2017), the actress did ice skating training for four months, according to Popsugar.

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Hilary Duff - The actress played Sharon Tate in an independent movie. You can see how much the production had to work to make her look like her character.

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Charlize Theron - According to FoodsForBetterHealth, the actress had to put on 14 kilos when she played a serial killer in the movie 'Monster' (2003).

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Matt Damon - 'Courage Under Fire' (1996) saw the actor lose approximately 18 kilos, according to the Daily Star.

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Anne Hathaway - The Daily Mail claimed that for her role as Fantine in 'Les Miserábles' (2012), the actress had to lose 11 kilos.

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Christian Bale - To play the starring role in 'The Machinist' (2004), the actor lost 28 kilos, according to Men's Health.

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Russell Crowe - Shape reported that for 'Body of Lies' (2008) the actor had to put on 29 kilos.

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Mila Kunis - For her role in 'Black Swan' (2010), Kunis followed a strict diet to lose nine kilos, according to the Daily Mail.

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Jonah Hill -

For the role of a police officer in '21 Jump Street' (2012), the actor had to lose 14 kilos, according to an article by the NY Daily News.

See also: Famous white actors who played people of color

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