Actors Who Totally Rebuilt Their Bodies For A Single Role

Acting is an inherently physical profession. A large part of the job deals with memorizing lines, tapping into extreme emotions, and bringing complex stories to life, but there's no denying that much of a thespian's life is spent physically embodying a wide range of characters. To convincingly portray another person, many actors spend a great deal of time perfecting the mannerisms, speech patterns, and physical charm of their roles, hoping to persuade the audience to suspend their disbelief and embrace the on-screen fantasy. 

Occasionally, this transformation is as simple as a costume or a well-made wig. Other roles require a total body transformation, causing actors to spend months in intense training to build a physical framework that will allow them to fully tell the story. Christian Bale is known for these chameleon-like transformations and seems to remake his body for every new role he takes on. Though he has become the industry's gold standard for body modification, Bale is not the first actor to undergo a physical overhaul while preparing for a role. The following is a list of 14 actors who have dedicated a significant portion of their lives to intense workouts and rigorous diets to transform their bodies for particular films. 

The following article includes descriptions of dieting and exercise.

Emma Stone was fresh off her Oscar-winning performance as Mia in Damien Chazelle's "La La Land," when a new role called for a total body overhaul. Stone signed on to play Billie Jean King, the real-life tennis star who shocked the world by beating the legendary Bobby Riggs in a match dubbed the Battle of the Sexes. Playing a woman known as "the mother of modern sports" required a different sort of conditioning than her dance training for the Los Angeles-based musical and an altogether different kind of physical presence. 

Stone worked with trainer Jason Walsh to bulk up, adding 15 pounds of muscle to her diminutive frame. Hoping to combat many women's misconception that heavy weight training can lead to a masculine physique, Walsh designed grueling workouts involving agility exercises like pushing a 200-pound sled and using heavy weights with various exercises like single leg squats, weighted pushups, and 185-pound deadlifts. Stone also bumped up her caloric intake with protein shakes made with ashwagandha, spinach, and protein powder. To play the woman John McEnroe described as "the single most important person in the history of women's sports," Stone not only challenged herself but long-held stereotypes about feminine fitness.

"Raging Bull" is the godfather of boxing movies. Martin Scorsese's black and white masterpiece is based on "Raging Bull: My Story," the memoir of boxer turned comedian Jake La Motta. The film was a passion project for De Niro, who embarked on a year of training and put on 20 pounds of muscle to play the legendary pugilist. He reportedly went 1,000 rounds in the ring with La Motta himself, who served as a technical advisor on the film. Part of De Niro's transformation included three professional fights, of which De Niro won two, causing his real-life counterpart to believe he could have become a professional boxer in another life.  

Scorcese began filming La Motta's boxing career, then took a four-month hiatus during which his star underwent another dramatic transformation. De Niro traveled to Italy and began binging the rich local cuisine, packing on an additional 70 pounds to play the out-of-shape boxer in his later life. It was this weight loss and gain that ultimately drew De Niro to the role. At the Hollywood Reporter's Actor Roundtable of 2019, De Niro recalled, "I thought the graphic difference of being out of shape and then being a young fighter really was interesting. I thought I'd like to see if I could gain that weight." 

While many of us were nursing backyard gardens and sourdough starters during the 2020 lockdowns, Chris Hemsworth was working out. With nothing else to occupy his time, the "Thor” actor took to swimming, heavy weight lifting, and martial arts. He supported this punishing activity by eating nearly 6,000 calories a day. As a result, Hemsworth arrived on the "Thor: Love and Thunder" set more muscular than ever. 

However, Hemsworth noted that something about his eighth appearance as the Asgardian God of Thunder seemed different. Perhaps due to the grueling production schedule, a higher target weight than in previous films, or simply the fact that he's getting older, the MCU veteran noted that reprising his role for the film "was just exhausting... I don't know, maybe I'm getting old, but things just started to hurt more." Hemsworth's wife, Elsa Pataky, was reportedly not thrilled with his ultra-jacked physique. Hemsworth hinted to People that this could be the last time he commits to such rigorous preparation: "They can give me a fancy muscle-y costume next time. I'm done."

Of all the transformations on this list, few are as rigorous as Hilary Swank's preparation for "Million Dollar Baby." Making her breakout performance as the titular "The Next Karate Kid," the actress was no stranger to physical roles. To convincingly play a boxer, Swank was initially asked to add 10 pounds of muscle to her naturally thin frame. When this didn't produce the desired results, she added another 9 pounds to portray the lonely boxer, Maggie Fitzgerald.

With only three months to prepare, Swank began a highly orchestrated program, including four-hour workouts six days a week. Each session began with two and a half hours of boxing, followed by two hours of heavy lifting. This weight gain also required Swank to up her caloric intake and consume more than 200 grams of protein a day. She accomplished this massive increase by drinking egg whites and flaxseed oil. To build bulk, Swank needed to eat every 90 minutes and would wake herself up in the middle of the night to down additional protein shakes. Despite these frequent interruptions, Swank made sure to get nine hours of sleep per night to allow her muscles to rest and repair. Her performance earned Swank a second Oscar, and "Million Dollar Baby" remains one of the most devastating and beloved sports movies of all time.

One of the most dramatic Hollywood makeovers in recent memory is the stunning transformation of Chris Pratt. Before 2014, the doughy funny-man was known as the bumbling but loveable Andy Dwyer on "Parks and Recreation." After winning the role of Peter Quill (aka Star-Lord) in "Guardians of the Galaxy," Pratt shocked the world by posting a shirtless selfie, revealing a chiseled torso, having lost 60 pounds in just six months. 

Pratt reportedly took to the program with gusto, noting that it gave him "a sense of absolute control." To achieve the body of a Star-Lord, Pratt teamed with personal trainer Duffy Gaver, who started the out-of-shape actor with bodybuilding exercises and then added high-intensity training, including a signature workout of just three body-weight moves. Pratt repeated a cycle of pull-ups, push-ups, and air squats, completing five reps of each as many times as possible within five minutes. In addition to diligent exercise, Pratt believes his rapid weight loss ultimately amounted to a series of small choices. He gave up alcohol for all six months of training and opted for lighter fare, reminding himself, "I eat that hamburger and that's 1,200 calories, and I'm gonna work out tomorrow and burn 800 calories. I may as well eat a salad here, still do that workout, and then I'm actually making progress."

As it turns out, Kit Harington knows something about exercise. The "Game of Thrones" star shook off the fur cloaks and black regalia of the Night's Watch for the more revealing robes of a gladiator in Paul W.S. Anderson's first-century disaster film, "Pompeii." In addition to a highly specific 1,800-calorie diet, Harington dove into a grueling program involving two hours of fight training followed by an hour of weight lifting and another hour of cardio.

Harington committed to the role with an intensity that at times became scary, telling Vulture, "I became obsessed with it ... to the point where I was going to the gym three times a day for six days a week." Fearful of body dysmorphia, his trainer intervened and set the actor on a more sustainable path. Harington enjoyed performing his own stunts for "Pompeii," and a "gladiator boot camp" provided unexpected benefits for his "Game of Thrones" character. After Harrington returned to Westeros with an impressive new set of skills, director Neil Marshall reportedly called Anderson to thank him for giving the show's star some additional training.    

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In 2016, 61-year-old J.K. Simmons set the internet on fire by posting gym pictures of himself lifting weights with impossibly ripped and veiny biceps and a bushy gray beard. Initial reports claimed this transformation was sparked by his casting as Commissioner Gordon in the 2021 film "Justice League." However, the Oscar-winning actor insisted that after years of dramatically fluctuating weight and health, he simply decided to live the rest of his life in what he calls "decent shape." It just so happens that director Zack Snyder is a "fitness maniac," and they found common ground in their various routines while filming. 

Simmons worked out two to three times a week with his personal trainer Aaron Williamson using a technique called Cumulative Blood Volume Training designed to pump as much blood to targeted muscles as possible. Dual workouts include cardio and strength training, consisting of exercises like hammer curls, pushups, a variety of crunches, and ironically, a move called the Superman in which he lifts his body off the floor in an imitation of the caped hero flying toward danger. Simmons also revamped his diet to include mostly lean protein, fruits, and vegetables.