Read some wild stories on how your favorite stars got swole for a role.

10 actors who packed on muscle for a movie — and how they pulled it off

Read some wild stories on how your favorite stars got swole for a role.

By Skyler Trepel

May 11, 2026 11:32 a.m. ET

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Linda Hamilton in 'Terminator 2,' Zac Efron in 'The Iron Claw,' Kumail Nanjiani in 'Eternals'. Credit:

Everett; Brian Roedel/A24; Sophie Mutevelian/Marvel

There’s few things more aspirational — albeit in an intimidating sort of way — than watching a movie star transform their physique for a role. But the dirty truth is that this kind of physical makeover is a full-time job in itself.

Actors have been known to take on extreme diets and training regimens, and that’s in addition to developing different physical disciplines within a matter of months.

While these physical reinventions may inspire some of us to want to follow in their footsteps, they often come at significant physical and emotional cost — not to mention the time commitment.

As *It’s Always* *Sunny *star* *Rob McElhenney joked, looking like him is impossible unless you’ve got excess time and money. “Make sure you have a studio pay for the entire thing, because it could become exceptionally expensive,” he told *Men’s Health* in 2021. “I think if you just do all those things, then you too can have an absolutely unrealistic body type, such as me.”

From Linda Hamilton bulking up for *Terminator 2* to Michael B. Jordan and Jake Gyllenhaal reinventing their bodies to step into the ring, here are 10 actors who got swole for a role.

Gerard Butler, 300 (2006)

Gerard Butler, not swole, in 2003 / Gerard Butler, swole, in '300'.

SGranitz/WireImage; Everett

For an army of 300 men to take on an army of 300,000, they're going to need a strong leader. That’s why Gerard Butler worked so hard to play the extremely swole King Leonidas in Zack Snyder’s stylish comic-book adaptation.

The Scottish action star put himself through a grueling regimen, working out six hours a day — two hours each of CrossFit training, bodybuilding, and fight choreography. The end result was impressive, but Butler admitted it was not necessarily good for his health.

“That was the best shape I have ever been in in my life,” Butler told *The Hollywood Reporter* in 2021. “In some ways I was ruining my body, but I was looking amazing doing it.”

Butler's legendary workout was designed by Hollywood trainer Mark Twight. It consisted of 300 reps spread across several exercises: pull-ups, deadlifts, push-ups, box jumps, floor wipers, and kettlebell clean-and-presses — all capped off with more pull-ups. Whew!

Zac Efron, The Iron Claw (2023)

Zac Efron, not swole, in 2016 / Zac Efron, swole, in 'The Iron Claw'.

Gregg DeGuire/Getty; Brian Roedel/ A24

*The Iron Claw *dramatizes the real-life tragedy of the infamous Von Erich family, who helped transform professional wrestling into a mainstream spectacle.

Of the family’s six sons, only one lived past the age of 33. Zac Efron portrays that son, Kevin Von Erich, in this fictionalized family saga, which also stars Jeremy Allen White and Harris Dickinson. Efron was already ripped when he took the role, but he bulked up considerably to play the wrestler.

“That necessity to be perfect — it became an obsession… It was a singular focus for months. And your life goes out the window during prep,” Efron told *Variety* in 2023. “Then I was able to incorporate old-school bodybuilding and Olympic lifting and really achieved that specific look of pro wrestlers, which was really hard.”

After previously admitting he'd overtrained and used diuretics for his *Baywatch *(2017)* *bod, he said he learned from his mistakes and refused to sacrifice his health for a role in the same way again.

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Jake Gyllenhaal, Southpaw (2015)

Jake Gyllenhaal, not swole, in 2011 / Jake Gyllenhaal, swole, in 'Southpaw'.

Carlos Alvarez/Getty; Everett

In Antoine Fuqua’s boxing drama *Southpaw*, Jake Gyllenhaal got shredded to play Billy Hope, an undefeated champion whose life falls apart after his wife’s accidental death from an errant gunshot. The film follows his attempt to rebuild both his career and personal life.

For the acclaimed actor, getting into boxing shape was about far more than simply adding 15 pounds of muscle.

“I knew very little about the science, the techniques of boxing before we started,” Gyllenhaal told PEOPLE in 2015. “My thought was, if I train twice a day, I can make five months, 10 months [of training]. That's what we did. I spent all my time surrounded by Antoine, my trainer, and the fighters I was boxing with.”

According to trainer Terry Claybon, the actor did 1,000 sit-ups per day, 100 pull-ups, 100 tricep dips, and two sets of 100 speed squats. Then there was jump rope, the heavy bag, and a combination of footwork exercises, punching, and sparring.

He also ran 8 miles daily for five days each week — and regularly had to flip a 300-pound tractor tire 20 times.

Linda Hamilton, Terminator 2: Judgment Day (1991)

Linda Hamilton, not swole, in 1987 / Linda Hamilton, swole, in 'Terminator 2'.

Ron Galella, Ltd./Ron Galella Collection via Getty; Everett

Fresh off giving birth, Linda Hamilton underwent an intense physical regimen for the sequel to James Cameron's *The Terminator*.

Thirteen weeks before filming, Hamilton began training for three hours a day, six days a week and maintained the routine through six months of filming. Her workouts consisted of aerobic exercises — running, biking, swimming, and stair climbing — followed by free weights mixed with mini-trampoline work, and concluding with walking lunges or an abdominal series.

It worked. The character we see onscreen is a lean, ferocious heroine. Hamilton told EW in 1991 that she also worked intensively with Israeli soldier and weapons expert Uzi Gal to transform into a fighter — but she did set limits.

”[I did] judo and heavy-duty military training. I learned to load clips, change mags, check out a room upon entry, verify kills. It was very vicious stuff. And it was sheer hell,” Hamilton said. ”He would have liked to have had me swimming in the ocean at dawn with a 50-pound pack… but I have a son who needed me, too.”

Michael B. Jordan, Creed (2015)

Michael B. Jordan, not swole, in 2013 / Michael B. Jordan, swole, in 'Creed'.

Theo Wargo/Getty ; Everett

Playing the son of Rocky Balboa’s (Sylvester Stallone) rival-turned-bestie required intense training, but Michael B. Jordan was up for the challenge. In 2015, Jordan spoke with *Sports Illustrated *about the regimen he adopted to play Adonis “Donnie” Creed.

“Maybe about a year [before filming], I started to really crack down on training,” Jordan said. “My diet completely changed. So I want to say grilled chicken, brown rice, broccoli — variation of a protein, carb, and a vegetable — and a gallon-and-a-half of water a day, which is not as easy as it sounds. Then I worked out six days a week, two to three times a day, and if you consistently do that for about a year you'll start to see some physical results.”

As for the boxing, Jordan trained in the ring for three hours a day. He also consulted with Stallone, who had boxing insight of his own to share.

Taylor Lautner, Twilight: New Moon (2009)

Taylor Lautner, not swole, in 2008 / Taylor Lautner, swole, in 'Twilight: New Moon'.

Chelsea Lauren/WireImage; Kimberley French/Summit

Transforming from human to werewolf onscreen is one thing... but it’s not nearly as challenging as achieving a werewolf-ready physique offscreen. Taylor Lautner found that out the hard way when training for *Twilight *sequel *New Moon*, which saw him go from friend to love interest for Bella (Kristen Stewart).

“It was my entire life,” Lautner told PEOPLE in 2023. “In the first movie, I was 140 pounds, and in *New Moon* I was 175. So yeah, that wasn’t my natural body. I had to work very hard for it and very hard just to maintain it.”

Lautner hit the gym two hours a day for five days per week, but the most difficult part involved changing his diet to support the necessary weight gain. He had to eat 3,200 calories a day. To accommodate his busy schedule, he carried around bags of almonds, beef patties, and sweet potatoes to snack on throughout the day.

Rob McElhenney, It’s Always Sunny in Philadelphia (2018)

Rob McElhenney, not swole, in 2011 / Rob McElhenney, swole, in season 13 of 'It's Always Sunny'.

John Shearer/WireImage; Everett

Rob McElhenney is known for playing the insecure, self-appointed group enforcer Mac on *It’s Always Sunny in Philadelphia*, which he co-created.

As something of a satirical goof, the actor gained a significant amount of weight — or “mass,” as the character insisted on calling it — for the show’s seventh season. After transforming into “Fat Mac,” he decided to one-up himself by becoming “Jacked Mac” for season 13.

The transition from skinny to hefty to ripped should come with a “don’t try this at home” sticker, as he readily admitted while describing his one-of-a-kind insights into the process.

"I’m gonna break it down for you, because it’s actually quite simple, and anybody can do this. Anybody on the planet can do this. First thing’s first: if you have a job — like a 9-5 job — quit that,” the shapeshifting actor said. “Now, do you like food? Forget about that, because you’re never gonna enjoy anything you eat… Now, do you have a family? Like a significant other or kids? Yeah, forget about them. You’re not going to have time to deal with them.”

To achieve his physique, McElhenney hired a personal chef, visited a physical therapist regularly, worked out twice a day, and enlisted Arin Babaian, Channing Tatum’s *Magic Mike* trainer.

Kumail Nanjiani, Eternals (2021)

Kumail Nanjiani, not swole, in 2018 / Kumail Nanjiani, swole, in 'Eternals'.

Kevork Djansezian/Getty; Sophie Mutevelian/Marvel

Kumail Nanjiani grew up in India reading comics and watching action movies. Naturally, when he was cast in *Eternals* as the MCU’s first South Asian superhero, he wanted to physically fit the superhero mold. Thus began a rigorous training process as Nanjiani prepared to play Kingo, an alien posing as a Bollywood star.

Marvel was comfortable with Nanjiani’s original physique, but the actor wanted to keep up with the likes of Thor and Captain America. The comedian’s diet consisted of five meals a day, including the same breakfast — a variation of eggs with chicken or steak — in addition to daily workouts. He even used electric muscle stimulation to help his muscles grow.

“I had to change my relationship to pain,” he told *Men’s Health* in 2020. “You’re so designed to avoid it, but in that situation you really have to be okay with it. You have to *want* it. It’s almost trying to rewire your brain.”

Even today, Nanjiani maintains his physique with a rather unique motivation. As he joked in his most recent stand-up special, he has no reason to still have the body of a superhero — he just doesn't want to give his critics the satisfaction.

Hilary Swank, Million Dollar Baby (2004)

Hilary Swank, not swole, in 2003 / Hilary Swank, swole, in 'Million Dollar Baby'.

Dimitrios Kambouris/WireImage; Everett

Hilary Swank won her second Oscar as underdog boxer Maggie Fitzgerald in Clint Eastwood’s Oscar-winning *Million Dollar Baby*.

Swank's character rose from nothing to become a contender, and the actress had to do the same, albeit with lower stakes. To transform her body, the actress embraced an intensive workout regimen and added a ridiculous amount of protein into her diet. The path to her camera-ready, ring-ready physique was a demanding one.

“I started working out five hours a day — I had to eat 210 grams of protein a day,” Swank told *The Hollywood Reporter* in 2014. “I don’t know if you guys are aware of intake of protein… I had to eat 60 egg whites in a day and I couldn’t. So every morning I would drink them. I had to eat every hour and a half. So in the night, I had to wake up and drink protein shakes. I put on 23 pounds of muscle.”

Swank’s workouts consisted of two and a half hours of boxing, followed by weightlifting.

Charlize Theron, Mad Max: Fury Road (2015)

Charlize Theron, not swole, in 2013 / Charlize Theron, swole, in 'Mad Max: Fury Road'.

Jason Merritt/Getty; Everett

In one of the most fast-paced, action-packed films of the century, Charlize Theron starred opposite Tom Hardy in *Mad Max: Fury Road*. Theron stole the show as the rebellious Imperator Furiosa, who liberates the five enslaved wives of the tyrannical Immortan Joe.

Her buffed-up look in the film turned heads. The Oscar winner hoped that if she looked the part, her heroics would feel even more realistic — and more inspiring for women.

“I wanted to look like I had tremendous upper-body strength because there was so much physicality in the movie, especially with someone like Tom Hardy,” Theron told *The Independent* in 2015. “I just hate that idea of scrawny little girls fighting men off and then winning, so I did a lot of upper-body yoga to get my shoulders and neck strong. I look like a football player in this movie."

Theron filmed for up to 14 hours a day over 130 days in the hot Namibian sun, often wearing heavy equipment. She still squeezed in at least one hour a day of exercise on filming days to maintain the physique she had worked so hard to achieve.

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