Oppenheimer's Cillian Murphy Underwent a Drastic Transformation—& So Did These Movie Stars

Oppenheimer's Cillian Murphy essentially existed on "an almond a day," according to costar Emily Blunt. But he's hardly the first star to undergo a drastic transformation for a film.

By Jamie Blynn Jul 23, 2023 1:00 AMTags
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If you thought Christopher Nolan's Oppenheimer was nuts, just wait until you hear what went into making it.

After all, Cillian Murphy was looking to be explosive while transforming into J. Robert Oppenheimer, a.k.a. the father of the atomic bomb. 

"Oppenheimer had a very distinct physicality and silhouette, which I wanted to get right," the 47-year-old told the New York Times of the scientist, who died from cancer in 1967. "I had to lose quite a bit of weight, and we worked with the costume and tailoring; he was very slim, almost emaciated, existed on martinis and cigarettes."

The Irish actor's diet was a bit different, but just as jarring, according to his costar Emily Blunt, who plays Oppenheimer's wife Kitty

"He had such a monumental undertaking," she told Extra. "And he could only eat, like, an almond every day."

And, reader, he doesn't recommend you try this at home.

Check Out the Most Surprising Celeb Transformations of the Week

"You become competitive with yourself a little bit which is not healthy," he told The Guardian, refusing to share just how many pounds he dropped. "I don't want it to be, ‘Cillian lost x weight for the part.'"

And if you have, you know, gone to the movie theaters (or streamed anything at home), you know he's hardly the first shape up for a role—and he won't be the last.

Keep reading to see stars like Tom Hanks and Anne Hathaway who have undergone drastic transformations on screen...

Plus, Oppenheimer (also starring Matt Damon and Robert Downey Jr.) is out now.

Cillian Murphy

To play scientist J. Robert Oppenheimer in Christopher Nolan's Oppenheimer, the Irish actor "had to lose quite a bit of weight," he shared. "He was very slim, almost emaciated, existed on martinis and cigarettes." His diet? According to costar Emily Blunt, "He had such a monumental undertaking.And he could only eat, like, an almond every day."


Joaquin Phoenix

For his Joker role, the Oscar winner opened up about his 52-pound weight loss, telling the Associated Press, "Once you reach the target weight, everything changes. Like so much of what's difficult is waking up every day and being obsessed over like 0.3 pounds. Right? And you really develop like a disorder."

J.K. Simmons

The Spider-Man alum shocked fans when he debuted his bulging biceps, which were displayed in Justice League.

Jake Gyllenhaal

"I'd say my mother was worried," he previously told E! News after losing 30 pounds for Nightcrawler. "I would say she just wanted me to be careful. But she also knew and knows how seriously I take what I do and she respects that."

Michael B. Jordan

The Black Panther star gained nearly 30 pounds of muscle to transform into a rookie-turned-professional boxer in Creed.

Jared Leto

The actor and musician nabbed an Oscar for his riveting role in The Dallas Buyers Club. He lost 40 pounds for the role.

Chris Messina

The Mindy Project alum had to gain 40 pounds for his role in Live by Night.

Renée Zellweger

The Bridget Jones's Diary actress gained weight to portray the lovable character in the franchise's first and second films.

Matthew McConaughey

The Magic Mike hunk dropped 30 pounds to star in The Dallas Buyer's Club—which centered on the real-life story about a man dying from AIDS in the 1980s who treated himself with alternative remedies he smuggled into the United States from Mexico.

Rooney Mara

The actress looked lean and strong for her starring role in The Girl With the Dragon Tattoo.

Anne Hathaway

The Les Misérables star took home an Oscar for her role in the musical.

Christian Bale

He's no stranger to morphing for movie roles. In 2004, he lost more than 60 pounds for his role in The Machinist, and he did it again for the film The Fighter, opposite Mark Wahlberg. He also gained 40 pounds for American Hustle—and lost 70 pounds for Ford v Ferrari.

Jake Gyllenhaal (Again)

The actor looked more like a god than a prince for his role in 2010's Prince of Persia. Gyllenhaal said he studied Parkour, the French art of street running, in order to bulk up for the film.

Tom Hanks

"All it is is time and discipline," the Oscar winner told Time magazine of his role in 2000's Cast Away, for which he lost over 50 pounds to play a man stranded on an uninhabited island.

50 Cent

The ripped rapper shocked fans with a photo of himself looking slender. He reportedly went from 214 to 160 pounds in just nine weeks to play a football player diagnosed with cancer in Things Fall Apart.

Robert De Niro

Shaping up for movie roles is nothing new. The legendary actor earned an Oscar nom for his role as terrifying tattooed rapist Max Cady in the 1991 thriller Cape Fear.

Christian Bale (Again)

In order to portray former Vice President Dick Cheney in the 2018 biopic Vice, the star sported a fuller figure

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