Sydney Sweeney has left her quintessential blonde and busty physique behind in her latest film, transforming into Hall of Fame boxer Christy Martin for the upcoming biopic.
The actress, 28, said she put on 35lbs during a three-month span in which she exercised frequently and consumed protein shakes.
However Sydney is by no means the first star to put her body through a gruelling training scheme in order to play a part, with many stars subjecting themselves to shockingly low calorie diets and intense workouts for the sake of their characters.
Most notably Christian Bale lost 62lbs, eating just a tin of tuna and an apple a day to play the emaciated Trevor Reznik.
Similarly Cillian Murphy survived on just an almond a day for his role in Oppenheimer and Anne Hathaway even went on a 13 day starvation period during filming for Les Miserables.
At the other end of the spectrum Charlize Theron has been known to gain weight for her roles, indulging in doughnuts and crisps.
The most dramatic celebrity film transformations: From Christian Bale’s extreme 62lbs weight loss (pictured) to Cillian Murphy’s ‘almond a day diet’ and Charlize Theron piling on the pounds
Sweeney Sweeney said she ‘put on 35 pounds during’ a three-month span for her role in Christy, exercising frequently and consuming protein shakes
Christian Bale
Christian Bale has had one of the most dramatic body transformations in Hollywood history after the actor lost 62lbs for psychological thriller The Machinist.
The star slashed the number on the scales from 182lbs to just 120lbs for the character of Trevor Reznik who was emaciated due to his insomnia.
Christian revealed he lost the weight in just four months after surviving on 200 calories a day while still exercising, eating just a tin of tuna, an apple and a black coffee a day.
However radical transformation wasn’t originally in the script. Christiana is 6ft tall, however the writer was only 5ft6.
Christian’s co-star Michael Ironside, explained how the weight loss was the result of a simple typo.
‘The writer is only about five-foot-six, and he put his own weights in.’
‘And then Chris did the film and Chris said, “No, don’t change the weights. I want to see if I make them.” …
‘So those weights he writes on the bathroom wall in the film are his actual weights in the film.’
Christian has had one of the most dramatic body transformations in Hollywood history after the actor lost 62lbs for psychological thriller The Machinist (pictured left in 2002 and right in 2004)
After his weight plummeted to 121lbs, the actor swiftly bulked up again in just six weeks to play the Caped Crusader in Batman Begins by gorging on pizza and ice cream (pictured in 2005)
Christian also smoked cigarettes to help reduce his appetite.
He told GQ: ‘Also, at the time I was engaged in a very filthy habit of smoking. So, I was rolling my own cigarettes and sitting there puffing away.’
After his weight plummeted to a shocking 121lbs, the actor swiftly bulked up again in just six weeks to play the Caped Crusader in Batman Begins by gorging on pizza and ice cream.
He said: ‘I overdid it because I was enjoying gorging. I was ignoring advice about taking it slowly because my stomach had shrunk, and I should just go with soups.
‘I was straight into pizza and ice-cream and eating five meals in a sitting. My stomach expanded really quickly. I got very sick during that time but I enjoyed getting sick. I didn’t mind it at all.
‘In that short amount of time I did actually go from 121lbs right back up to 180lbs which is way too fast so that resulted in some doctor visits to get things sorted out.’
Charlize Theron
Charlize Theron left her stunning red carpet self behind when she transformed herself into real-life serial killer Aileen Wuronos for her 2003 film Monster (pictured R, pictured L in 2025)
Over a decade later the star pulled off a similar feat for 2018’s Tully, which saw her gain some 50lbs to play a mother on the brink of a mental breakdown
Charlize Theron left her stunning red carpet self behind when she transformed herself into real-life serial killer Aileen Wuronos for her 2003 film Monster.
The actress, who was in her 20s at the time of filming, gained 30lbs for the role after embarking on a diet of doughnuts and potato chips.
The fatty, sugary diet also affected the star’s skin and her usual radiant complexion looked markedly more pallid and blotchy on screen.
However the transformation paid off and Charlize went on to win the Oscar for Best Actress after her performance in the film.
Over a decade later the star pulled off a similar feat for 2018’s Tully, which saw her gain some 50lbs to play a mother on the brink of a mental breakdown.
But while it had been easy to gain and lose weight for Monster, Charlize struggled with the Tully transformation and spoke of falling into a depression as a result of the bad diet.
‘It was brutal in every sense,’ she explained at the time. ‘This time around, I really felt it in my health. The sugar put me in a massive depression.
‘I was sick. I couldn’t lose the weight. I called my doctor and I said, “I think I’m dying!” And he’s like, “No, you’re 41. Calm down”.’
Cillian Murphy
Cillian Murphy has previously detailed the extreme lengths he went to in a bid to portray the physicist on screen, losing weight to mirror his ‘almost emaciated’ frame
Oppenheimer dominated all the award shows of 2024, earning Cillian Murphy Best Actor at the BAFTAs, Oscars, SAG and Golden Globe awards.
And the Irish actor has previously detailed the extreme lengths he went to in a bid to portray the physicist on screen, losing weight to mirror his ‘almost emaciated’ frame.
His co-star Emily Blunt spoke about Cillian’s drastic transformation, telling how he only survived off an ‘almond a day’ in his gruelling diet.
Meanwhile Cillian warned that his transformation wasn’t ‘healthy’ and he took over five months to prepare himself both physically and emotionally for the role.
Speaking to the New York Times he confessed that he ‘loved’ the physicality of preparing for the role, telling how he wanted to lose weight to give Oppenheimer a ‘wide-eyed look’ to covey the fact that he ‘never ate’.
Cillian also said he was testing himself on how little he could eat, confessing that he ‘doesn’t advise’ the extreme diet.
He told The Guardian: ‘You become competitive with yourself a little bit which is not healthy. I don’t advise it.’
The actor didn’t reveal exactly how much weight he lost for the role, but told how the hectic nature of filming made him stop worrying about eating.
He slept for a few hours during filming, he said, adding: ‘I was running on crazy energy; I went over a threshold to where I was not worrying about food or anything.
‘I was so in it, a state of hyper… hyper something, but it was good because the character was like that. He never ate.’
Anne Hathaway
Anne Hathaway shed 25lbs for her role as Fantine in the film adaptation of Les Miserables back in 2012 (R) (pictured L in May)
Anne Hathaway shed 25lbs for her role as Fantine in the film adaptation of Les Miserables back in 2012.
The actress embarked in a drastic diet which saw her lose 10lbs in just three weeks prior to filming, and 15lbs during production as part of a starvation diet.
‘I just had to stop eating for a total of 13 days shooting. I was on a starvation diet to look like I was near death in a film… but I went at it with a plan and I had a guide, a nutritionist kind of helped me with it.’
It was later reported she had survived largely on lettuce leaves and a diet of porridge paste.
Speaking to Vogue, she said: ‘Looking back on the whole experience – and I don’t judge it in any way – it was definitely a little nuts.
‘It was definitely a break with reality, but I think that’s who Fantine is anyway.’
However, years later as she looked back on the drastic lengths she went to, Anne said she had become ‘really sick’ after losing the weight.
In 2019 she told People magazine she ‘wasn’t in a good place’ while filming Les Miserables.
She said: ‘I’d lost an unhealthy amount of weight in two weeks. I didn’t know anything about nutrition. I taxed my body, and my brain bore the brunt of it for a while. I just felt very anxious and very lost at that time.’
Anne added: ‘That weight loss was not a long-term good thing for my health, and it took a really long time to come back from it.’
Matthew McConaughey
Matthew McConaughey underwent a dramatic body transformation after he traded in his muscular Magic Mike frame (L) to lose 40lbs to play Ron Woodroof in Dallas Buyers Club (R)
Matthew McConaughey underwent a dramatic body transformation after he traded in his muscular Magic Mike frame to lose 40lbs to play Ron Woodroof in Dallas Buyers Club.
The actor embarked on a strict diet of Diet Coke, egg whites for breakfast and a piece of chicken or five ounces of fish and a small side of vegetables a day to slim down shifting from 188lbs to 135lbs.
The only snack he was allowed was tapioca pudding, which McConaughey admitted to eating with the smallest spoon possible to make it last longer.
‘I met with a nutritionist. I gave myself four months to lose the weight. I had my programmed meals, lost 3.5lb a week – like clockwork – and got down to my desired weight,’ he said at the time.
He insisted that losing weight was ‘honestly not that difficult’ but learning to re-progamme his life was the toughest challenge.
He said: ‘You have to reprogramme all of your habits, and the days get so long. You think it must be lunchtime already, and it’s only 9.30 in the morning.
And as the weight dropped from his muscular 183lbs to a scrawny 143lbs, so did his strength.
‘I would do five push-ups and be sore. I would run 30 feet and my legs would lock up.’
Yo-yoing the other way, he then gained 47lbs in the next six months for his role as Kenny Wells in the 2016 film Gold (pictured in 2015 on set)
Yo-yoing the other way, he then gained 47lbs in the next six months for his role as Kenny Wells in the 2016 film Gold.
Eating whatever he wanted, Matthew indulged in pizza and cheeseburgers and also quit exercise, deciding it was even too hard to walk up just one flight of stairs when an elevator was available.
Talking to Page Six, he said: ‘My favorite food is cheeseburgers, so I was eating cheeseburgers all the time.
‘I was trying out all these fast food restaurants that I’ve never had, or I’ve only had one time. Not that much sweets. Cheeseburgers and beer will do the trick.’
He later said the biggest challenge was trying to shed the weight afterward.
‘The hard part was getting down…I would go from 217 to 211, easy. Then 211 to 209. Crossing that 210 mark was really tough. Then [going from] 209 to 201: easy,’ he said.
Michael Fassbender
Michael Fassbender lost nearly 40lbs over 10 weeks to play prisoner Bobby Sands who led the 1981 Irish hunger strike (pictured L in April)
Shedding as much weight as the doctor would allow, the actor restricted himself to 600 calories a day eating sardines, berries, and a handful of nuts
Michael Fassbender lost nearly 40lbs over 10 weeks to play prisoner Bobby Sands who led the 1981 Irish hunger strike.
Shedding as much weight as the doctor would allow, the actor restricted himself to 600 calories a day eating sardines, berries, and a handful of nuts.
He recalled in an interview: ‘I remember looking at myself and thinking, “God, there are bones sticking out here.”
‘I went for my final check-up after filming and my doctor said, “Last time you came in here you looked pretty bad. My assistant was outside and she saw you and said, “My God, that guy’s really ill, isn’t he?” She thought you had cancer.’ People don’t actually say anything [directly] to you.’
And Michael also felt the effects after filming, as when he was allowed to eat again he struggled with digestion.
‘My first meal was Japanese. It’s my favourite food. But I was freezing cold in the restaurant because my body hadn’t had to work to digest food in ages. I was sitting there at the table in my big North Face jacket.’
Hilary Swank
Similar to Sydney Sweeney, Hilary Swank underwent a physical transformation for her role as aspiring boxer Maggie in Million Dollar Baby (R) (pictured L in July)
Similar to Sydney Sweeney, Hilary Swank underwent a physical transformation for her role as aspiring boxer Maggie in Million Dollar Baby.
The actress was given just 90 days before filming started to turn her body into that of a dedicated athlete who had years of training under her belt.
The star revealed at the time: ‘My training was two and a half hours of boxing and approximately an hour and a half to two hours lifting weights every day, six days a week.
‘The producers asked me to gain 10 pounds of muscle. I gained 19 pounds of muscle. I started at 110 and went to 129. And in order to do that, I had to eat 210 grams of protein a day.’
Chris Hemsworth
Chris Hemsworth shocked fans after sporting a much leaner physique when he took on the part of a shipwrecked sailor In The Heart Of The Sea back in 2015 (R) (pictured L in Thor)
Chris Hemsworth shocked fans after sporting a much leaner physique when he took on the part of a shipwrecked sailor In The Heart Of The Sea back in 2015.
The Australian actor took to social media at the time to share a snap of himself during filming, showing the results of his more than 15lbs weight loss.
‘Just tried a new diet/training program called “Lost At Sea”,’ he captioned alongside the photo.
‘Wouldn’t recommend it.. #IntheHeartoftheSea,’ he said.
Consuming only 500 calories a day, Chris told Entertainment Weekly: ‘When I started [filming], I was leaner than my Thor weight, anyway, because I’d been on Michael’s film.’
‘When you’re already starting off lean, it’s brutal to chew through that kind of weight. Every pound feels like a kilogram.’
To convincingly play the parts of starving men, the cast members’ diets were steadily reduced in the lead up to filming in the Canary Islands.
Zac Efron
Zac Efron (pictured left in High School Musical ) undertook an extreme make-over for Baywatch in 2020 – leaving him with a ripped body and incredible six pack (R)
He’s never been out of shape after soaring to fame as teen hearthrob Troy Bolton.
However Zac Efron undertook an extreme make-over for Baywatch in 2020 – leaving him with a ripped body and incredible six pack.
Yet while he may have aesthetically looked incredible, the actor later told Men’s Health how creating that body led to serious mental health issues.
The star stuck to a diet of organic protein and leafy greens and drank diuretics, which are medications that help the body eliminate excess fluid and salt by increasing urine production.
He also underwent months of intense training, with workouts starting at 4am leaving him feeling sleep deprived.
He said: ‘I started to develop insomnia, and I fell into a pretty bad depression, for a long time.
‘Something about that experience burned me out. I had a really hard time re-centering.’
In 2023 Zac took on another physically demanding role as wrestler Kevin Von Erich for the 2023 biopic The Iron Claw working out for multiple hours every day to gain 15lbs of muscle
However the brutal regime didn’t completely deter Zac from taking on another physically demanding role when he starred as wrestler Kevin Von Erich for the 2023 biopic The Iron Claw.
Zac told Variety that he worked out for multiple hours every day and practiced volume training to gain about 15lbs of muscle.
He also revealed that he would wrestle while filming the matches, which lasted seven to 15 minutes long, multiple times a day and consecutive days in a week.
The former Disney star revealed that he worked out so much that he became ‘obsessed.’
‘It was a singular focus for months,’ he told Variety. ‘And your life goes out the window during prep. That necessity to be perfect… became an obsession.’
