11 of the biggest transformations actors have made for roles, from Christian Bale to Charlize Theron

As Mark Wahlberg reveals a new look for his coming role, we take a look back at some of the biggest transformations actors have undergone for a role

Christian Bale lost almost 30kg for his role in 'The Mechanist'.

Jake Gyllenhaal gained almost 7kg of muscle and trained for six hours a day for his role in 'Southpaw'.

Jonah Hill shed more than 20kg for 'Maniac'.

Matthew McConaughey lost 22kg for 'Dallas Buyers Club', which he achieved by following a gruelling diet which involved him eating fish, egg whites and tapioca pudding.

Charlize Theron gained more than 13kg for her role in 'Monster'.

50 Cent lost 24kg by following a liquid diet for 'All Things Fall Apart'.

Natalie Portman lost 10kg for her Oscar-winning role in 'Black Swan'.

Chris Pratt shed 27kg for 'Guardians of the Galaxy'.

Tom Hardy underwent an intense training programme for 'Bronson'.

Jared Leto piled on 30kg and gave himself gout for his role in 'Chapter 27'.

Christian Bale gave himself a herniated disc in his back due to slouching for 'American Hustle'.

For actors, transformation is the name of the game. But some do more than just take on a new character for their starring role.

Self-confessed fitness fanatic Mark Wahlberg recently shared a side-by-side body transformation picture to his Instagram page, revealing to his 16 million followers that he had gained almost 10 kilograms in just three weeks.

In a separate video posted to Instagram, Wahlberg and a friend compare their body transformations in the gym.

“Kenny’s down 50 [pounds, 22.6kg] and I’m up about 20 [9kg],” he captioned the image. “I’m going up another 20. Yes it’s for a role.”

Wahlberg's dramatic transformation is for his coming role in film Stu. He'll play a former fighter who moves to Los Angeles to become an actor, before having an accident which leads him to change paths completely and become a priest.

"After we do the boxing scenes, I get to put on as much weight as possible over the course of the film, so I'm challenging myself to put on 30 pounds [13kg] in the next six weeks," the Ted star said in an interview with Jimmy Kimmel in April.

“They want me to do it as healthy as possible. I’m like, ‘Dude, I’ve been on such a regimen for so long, I just want to eat everything in sight.’ I want to go to bakeries, I want to go to Denny’s, I want to get pancakes. I want to get everything that I could possibly get my hands on.”

While Wahlberg may be enjoying his body transformation, some stars have had to put themselves through much more extreme paces for roles.

Here are 11 extreme celebrity transformations:

1. Christian Bale, ‘The Machinist’

Perhaps one of the most dramatic transformations made for a role in the history of film was that of Christian Bale for The Machinist. Bale's character, Trevor Reznik, suffers from extreme insomnia, which leads to severe weight loss.

Bale lost almost 30kg for the role, following a strict diet for four months,  when he ate only one can of tuna fish and one apple per day, the equivalent of about 260 calories. He was also allowed one black coffee and water. Bale also sped the process along with an intensive cardio regime.

Bale said the weight loss put him in a "zen" state of mind, before he was required to pack on the muscle for his next role in Batman Begins, gaining 45kg – reportedly only to be told to shed 10kg of that by director Christopher Nolan.

2. Jake Gyllenhaal, ‘Southpaw’

For his role as a middleweight boxer in the film Southpaw, Jake Gyllenhaal gained almost 7kg of muscle. The actor worked out for six hours a day over a period of six months to prepare for the film, training at a Las Vegas gym owned by champion boxer Floyd Mayweather.

Speaking about his transformation for the film, Gyllenhaal said: “The amount of time you have to put into it, the sacrifice that you put into your body, it's not something that you're eager to do again. It's a huge commitment.”

3. Jonah Hill, ‘Maniac’

Jonah Hill has transformed himself for a number of roles, including 21 Jump Street and The Wolf of Wall Street, however, perhaps his most dramatic transformation came for 2018 Netflix series Maniac. The star shed more than 20kg for the role, in which he starred opposite Emma Stone, after he gained weight for the film War Dogs, in which he portrayed real-life arms dealer Efraim Diveroli.

In an interview on The Tonight Show with Jimmy Fallon, Hill revealed he called on former co-star Channing Tatum for advice to help him get in shape.

"I gained weight for this movie War Dogs, and then I wanted to get in better shape, so I called Channing Tatum, and said, 'Hey, if I ate less and go to a trainer, will I get in better shape?'"

Tatum's to-the-point reply: “‘Yes … of course, you will, it’s the simplest thing in the entire world’.”

4. Matthew McConaughey, ‘Dallas Buyers Club’

Matthew McConaughey well and truly shook off his rom-com image in the Oscar-winning Dallas Buyers Club, in which he took on the role of real-life Aids patient Ron Woodroof, who challenged the US government to bring unapproved medication to other sufferers.

McConaughey lost 22kg to play the role, which he achieved by following a gruelling diet that involved him eating fish, egg whites and tapioca pudding.

"I did not torture myself. I was militant. The hardest part was making the damn choice," McConaughey said on an episode of The Joe Rogan Experience.

He added that he felt a responsibility to lose weight to authentically portray the character. "It was my responsibility," he said. "If I looked how I look now and played Ron Woodroof from Dallas Buyers Club, you are out of the movie the first frame."

He went on to win the Oscar for Best Actor for the role.

5. Charlize Theron, ‘Monster’

To take on the role of real-life serial killer Aileen Wuornos, Charlize Theron shook off her glamorous image, completely transforming both herself and her physique. Theron switched up her diet to help her gain more than 13kg. However, the star said, for her, the transformation was not just about gaining weight, it was about letting go of her usually strict regime in order to get into the right headspace for the role.

It clearly worked, as Theron was awarded the Best Actress Oscar for her efforts.

6. 50 Cent, ‘All Things Fall Apart’

Rapper 50 Cent is known for many things, and his usually ripped physique is one of them. However, the star, real name Curtis Jackson, shocked fans back in 2011 when filming All Things Fall Apart, in which he portrayed a football player who had been diagnosed with cancer.

He lost more than 24kg for the role, which he did by surviving on a liquid diet, and spending three hours a day on the treadmill for nine weeks. He also had a number of his tattoos removed for the role, to "save time covering them".

“I was starving,” the star later said in an interview.

7. Natalie Portman, ‘Black Swan’

To take on the role as a perfectionist ballerina, Natalie Portman lost almost 10kg for her Oscar-winning turn in Black Swan. Portman survived on a diet consisting of little more than carrots and almonds, and spent more than eight hours a day in rehearsals, during which she dislocated a rib.

"There were some nights that I thought I literally was going to die," the actress said about her preparation for the role. "It was the first time I understood how you could get so wrapped up in a role that it could sort of take you down.

"All dancers are always dancing with an extreme injury. Not just a sore muscle, they're dancing on a sprained ankle or with a twisted neck or something. You'll see them do incredible stuff and then limp off stage, straight to a bucket of ice. Part of the art is hiding all the pain."

8. Chris Pratt, ‘Guardians of the Galaxy’

Most superhero films mean business, as Chris Pratt found out when he was put through his paces for Marvel's Guardians of the Galaxy. The star shed 27kg thanks to a gruelling routine, courtesy of personal trainer Duffy Gaver and nutritionist Phil Goglia, who completely overhauled his diet and exercise routine.

The star said “three or four hours a day of just consistent, ass-kicking hard work” was what helped him transform himself for the role, along with a 4,000-calorie-a-day diet, and lots of water. “I was peeing all day long, every day. That part was a nightmare,” Pratt said.

9. Tom Hardy, 'Bronson'

For the 2009 biopic Bronson, in which Tom Hardy transformed himself into notorious prisoner Charles Bronson, the actor had to undergo an intense and very specific type of training. "To achieve dense muscle, you need a specific kind of training," he told AskMen. "Also, to 'become' Charlie Bronson, I had to quickly put a lot of weight quickly on my forearms, chest and neck. By the time I'd finished, my legs looked like those of a stork in comparison to the top half of my body."

10. Jared Leto, 'Chapter 27'

Jared Leto gained more than 30kgs to play John Lennon's assassin, Mark David Chapman, in Chapter 27 – a process which he later revealed gave him gout. His diet consisted of pizza, pasta, and melted Haagen-Dazs ice cream mixed with olive oil and soy sauce.

"Towards the end of the shoot, one of the glaring issues was the pain I had with my feet," he said after the film premiered at Sundance Film Festival in 2007. "I couldn't walk for long distances. I had a wheelchair because it was so painful. My body was in shock from the amount of weight I gained.”

11. Christian Bale, 'American Hustle'

Christian Bale makes the list again for another extreme body transformation, although for his role in 2013's American Hustle, he went in the other direction, gaining 19kg to play Irving Rosenfeld, a character based on infamous American con-artist Melvin Weinberg.

Bale also shaved part of his head for the role to mimic Weinberg's comb-over. The star also gave himself a herniated disc in his back as a result of his decision to give his character a slouched posture, dropping Bale's real-life height by three inches.