Dwayne Johnson has spent two decades being the biggest man in every room he enters. The most physically imposing action star in Hollywood, the guy who eats seven meals a day and trains before the sun comes up, that has been the brand, the identity, and for a long time, the ceiling.
Then Benny Safdie called.
The Smashing Machine, A24’s biographical drama about UFC pioneer Mark Kerr, required something Johnson had never been asked to do… shrink.
To do that, he first had to become even bigger than he already was, then systematically dismantle everything he had built over thirty years in professional wrestling and Hollywood.
“This transformation was something I was really hungry to do,” Johnson said at a press conference at the Venice Film Festival, where the film premiered in September 2025 to a standing ovation that made him cry.
“I had been very fortunate to have the career that I’ve had over the years and to make the films that I’ve made, but there was just a little voice inside of me that said, ‘Well, what if I could do more — I want to do more and what does that look like?'”
The Two-Phase Plan
When Safdie first approached Johnson about playing Kerr, he was direct about what he needed.
“Benny came to me, we had a good laugh about it, and he said, ‘I don’t know how to say this, and I don’t know if you’ve ever been asked this, you’re going to have to get bigger,'” Johnson told talkSPORT.
“I kind of laughed, but I knew he was right, because Mark Kerr was puffier. Mark was a big guy, a lot bigger than I was back then.”
Johnson asked for 24 hours to figure out how to approach it. He came back the next day with a plan nobody expected.
Rather than simply losing weight for the role, which is what most actors do when playing a fighter, Johnson decided he needed to first gain weight specific to Kerr’s particular physique, and then strip it all away.
Kerr, a two-time UFC Heavyweight Tournament champion who dominated the sport in the late 1990s, has what Johnson described to ESPN as a “rare one-of-one body.”
Not a bodybuilder’s physique. Not a sprinter’s physique. Something more specific, the body of a wrestler with fast-twitch muscle fibers, a particular kind of trap and neck development from years of takedowns and clinch work, quads built from constant shooting and lifting.
“To put on that kind of muscle is just different,” Johnson told ESPN. “So that’s why I went into an MMA camp, trained with real coaches, real MMA fighters, just to keep my movement.”
He gained approximately 30 pounds in the first phase. Then he lost over 60. The net swing from his heaviest point to his final on-screen weight was more than 90 pounds in total body composition change, the most dramatic physical transformation of his career by a significant margin.
Johnson’s Training Camp
Johnson’s MMA training camp began in April 2024, a month before principal photography started.
The timing was brutal. He had just concluded a separate 12-week training camp for WrestleMania 40. He took ten days off and started again.
The camp was based at Black House MMA gym, one of the most respected training facilities in combat sports.
Every single day began with cardio on an empty stomach. A weightlifting session followed after lunch.
An additional 15 to 20 minutes of cardio came after that. Then an hour to 90 minutes in the cage, actual MMA work, with real coaches and real fighters.
The diet shifted completely. The 8,000-calorie-a-day regimen that had built the physique audiences recognized from the Fast and Furious films and Black Adam was gone.
In its place: high-protein, low-sugar meals built around chicken, fish, and vegetables. Every meal, every session, every decision was oriented toward a single outcome.
“I’ve never worked harder,” Johnson told ESPN during a media roundtable. “And we like hard work, it’s what we all like to do. But man, I had never worked harder for a role.”
The work in the cage paid off in ways that went beyond the physical. Safdie told Johnson at the start of production that he would love to never cut away from him during the fight sequences, to use Johnson himself rather than stunt doubles.
“We have a great stunt double, we have two. I’d love to just use you,” Johnson recalled Safdie telling him. Because of those months in the gym, he could deliver.
22 Prosthetics And Four Hours In The Chair
Weight was only one dimension of the transformation. Every morning of production, Johnson sat in a makeup chair for three to four hours with Academy Award-winning makeup artist Kazu Hiro, who applied 22 individual prosthetics.
They included a restructured brow bone, cauliflower ears developed from years of wrestling and grappling, facial scarring, and a wig.
In his Vanity Fair interview, Johnson described the experience of watching the transformation accumulate piece by piece in the mirror.
“I just sat in front of that mirror for three to four hours and watched it all change,” he told the magazine.
“There were about 13 or 14 different prosthetics. Subtle, yet I think very impactful. By the time I got to set, I was Mark Kerr and I felt it, from how he walked to how he talked and how he looked at life.”
Emily Blunt, his co-star, plays Kerr’s former girlfriend Dawn Staples in the film. She described the first time she saw Johnson fully transformed as a complete disruption to the room’s atmosphere.
“I was really staggered by it. It changed the air in the room. Everyone just went very quiet,” she told journalists during the Venice press circuit.
“The transformation seemed like water in the desert. It was so magical.”
She added on Good Morning America that she had never seen anything like what Johnson brought to the role.
“I just felt he had this reservoir of incredible life experience that could be funneled into a role that demanded all of him. And I just thought he was astonishing.”
Getting Into Kerr’s Mind
The physical work was matched by an equally serious emotional and psychological process.
Johnson worked with a vocal coach to adopt Kerr’s speaking voice, softer, more tender, nothing like the booming charisma of the People’s Champion.
He spent significant time with the real Mark Kerr himself, asking questions, listening, internalizing. He listened to melancholic music to carry the emotional weight of Kerr’s story into each day’s work.
Johnson had actually known Kerr since the late 1990s, when both men were rising in their respective combat sports worlds at the same time.
Kerr was at the peak of his UFC dominance. Johnson’s career as Rocky Maivia in the then-WWF was still finding its footing.
They crossed paths during a period when the MMA and professional wrestling communities were witnessing a sudden and devastating wave of deaths, fighters and wrestlers dying from pills and drug addiction, with almost no support systems in place.
“No one can really relate to what it’s like to be the greatest fighter on the planet,” Johnson told Good Morning America.
“At one time, Mark Kerr was the greatest fighter on the planet — undefeated, dominant, and feared. But we can all relate to pressure, what that’s like, and having to deliver day in and day out in relationships and jobs.”
Kerr’s own response to Johnson’s performance came via an anecdote his son Bryce provided.
After seeing the film in New York, Bryce called his father and began whispering his reaction, almost afraid to say it out loud.
“Dad, he walks like you. He looks like you. He talks like you.” Kerr told ESPN: “It was just this whole narrative of the confirmation of his transformation into somebody other than Dwayne Johnson.”
Why This Role Mattered Personally To The Rock
The transformation goes deeper than craft.
Johnson has spoken in multiple interviews about the personal meaning of playing Kerr, a man whose story involves addiction, loss, and the brutal human cost of athletic dominance in an era before anyone was paying attention to what happened to fighters after the lights went off.
Kerr battled painkiller addiction during the late 1990s UFC boom, when the sport had no infrastructure for mental health or recovery support.
Johnson witnessed the same wave of addiction deaths in professional wrestling during the same period, friends and colleagues he lost to a crisis that the industry refused to acknowledge.
In playing Kerr, Johnson described the film as a tribute to those losses and an act of respect for a man whose story had never been fully told.
“This film, this role, and what it represents — it changed my life,” Johnson said at the Venice premiere, visibly emotional after the standing ovation.
The Smashing Machine earned Johnson a Golden Globe nomination — the most significant acting recognition of his career, and has been widely discussed as the performance that reframes what he is capable of as an actor.
Director Benny Safdie described the entire filmmaking process in characteristically vivid terms.
A therapist once told him that treating cancer involves taking blood out of the body, blasting it with radiation, then returning it, and that making a film works the same way. “You look at everything, you notice things and then it just gets put right back inside your head.”
Johnson and Safdie are already moving forward together again. Johnson confirmed he is now slimming down further, past even his Smashing Machine weight, to play a whimsical, eccentric 70-something-year-old character called the Chicken Man in Safdie’s next film, the fantasy project Lizard Music.
“I gained 30 pounds to play Mark Kerr and then came back down after that to my normal weight of around 250 or so,” Johnson told LadBible.
“Now I’m in the process of slimming down where I play a 70-something-year-old man. And we have time to do it, which is really nice. There’s nothing extreme about it. I can’t wait, because, again, it’s the opportunity that I have where I can immerse myself into something and disappear.”
For a man who spent thirty years being the most recognizable body in the room, disappearing appears to be exactly what Dwayne Johnson is chasing now.
