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Fitness

The Most Insane Celebrity Transformations

by Vidur Saini Published on Mar 31, 2025 Expert verified by Victor Martinez

This post may contain affiliate links (disclosure policy).

Celebrities that look like pro bodybuilders

Celebrities are the trendsetter when it comes to style, fashion or fitness. Watching your favorite celebrities go through a physical transformation can motivate and push you to start your own transformation, and there are some incredible transformations that some celebrities have undergone.

While it may not be the 1980s action stars like Arnold Schwarzenegger or Sylvester Stallone dominating the screen, there have been a lot of feature films over the past few years that have in shape actors. The fitness trend in Hollywood is even more prominent in the superhero universes of Marvel and DC.

In this post, our team at Generation Iron breaks down our top picks for the best celebrity transformations.

The 8 Most Insane Celebrity Transformations

Let’s take a look at the top 8 celebrity fitness transformations.

Christian Bale

The Most Insane Celebrity Transformations

Christian Bale has arguably the most radical transformations. Bale’s dedication and commitment to his roles are evident from what he is ready to put his body through. His transformation from The Machinist, where he was almost a skeleton, to Batman Begins where Bale sported a good amount of muscle mass, is nothing short of inspiring.

Gerard Butler

Gerard Butler wasn’t always the ripped King Leonidas we saw in the movie 300. Butler completed his insane transformation for the role of the Spartan king in a mere three months. Now, this is something all of us should work towards.

Kevin Hart

The comedian rockstar’s transformation came as a surprise to most. Kevin Hart was always in shape but he took his fitness to a whole new level when he showed off his tones muscle and ripped abs. Hart has partnered with Nike and promotes running.

Jake Gyllenhaal

Jake Gyllenhaal is someone who pretty often sports a ripped physique. He even gained 30 pounds and 15 pounds of lean muscle for his role in the boxing film Southpaw. In the beginning, Gyllenhaal worked out three hours a day and after two months his workouts were six hours long.

Chris Hemsworth

Chris has always been a fit guy but his level of fitness took a new turn when he started training for his role as Thor. We have to admit, Hemsworth looked nothing short of a demi-God after his transformation.

Jonah Hill

When Jonah appeared on The Tonight Show with Jimmy Fallon, he said: “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 eat less and go to a trainer, will I get in better shape?’

“And he said, ‘Yes, you dumb motherf*****, of course you will, it’s the simplest thing in the entire world.”

Jonah Hill was always known as a “fat guy” in Hollywood, but he certainly changed that!

Chris Pratt

chris pratt transformation

Chris Pratt had no other option but to get in shape for his role in the Guardians of the Galaxy. Pratt lost 60 pounds in six months. Chris’ trainer made him eat turkey with gravy every day and his workouts included sessions of P90X, running, swimming, boxing, kickboxing, and even a triathlon.

Hugh Jackman

Hugh Jackman first played Wolverine in the first edition of X-Men (2000). There has been a dramatic transformation in his physique ever since. On being asked about his diet, Hugh said, “The Wolverine diet is strict. It has about 4000 calories a day, maybe 4 and a half cause I’m bulking up. Always protein, 6 times a day, steam vegetables, and occasion brown rice.”

“I had to be in peak condition for the role. I went on a water dehydration diet so I can be as ripped and cut as possible. Twenty to thirty hours of not drinking any water and I had a nasty headache. You start cranking up.”


Best Celebrity Transformations Wrap Up

Which celebrity has the best physique according to you? There are certainly some great ones out there, so let us know which one impressed you the most.

Let us know in the comments below. Also, be sure to follow Generation Iron on Facebook and Twitter.

About Vidur Saini

Vidur is a fitness junky who likes staying up to date with the fitness industry and loves publishing his opinions for everyone to see.

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