Sydney Sweeney reveals what it really took to become boxing icon Christy Martin

10 November 2025

‘I became a fighter’ … in Christy. Photograph: Black Bear

When Sydney Sweeney signed on to play Christy Martin in the new biopic Christy, she knew the physical transformation would be intense. Yet nothing prepared her for the hits, bruises and mindset shift that came with stepping into the ring. In a wide-ranging interview with The Guardian, Sweeney spoke candidly about boxing full-contact, gaining over 30 pounds for the role and navigating the public perception that comes with celebrity.

The journey began with a training regime that might intimidate even seasoned athletes. Sweeney described daily routines filled with weight training, kick-boxing and hours spent in sparring sessions. “There were concussions, some bloody noses,” she said with a grin. “In between takes I’d be like ‘I think I won that round!’” She credited the actress who played Laila Ali an actual Team USA boxer for delivering one of her earliest concussions, setting the tone for authenticity in the process.

Gaining muscle and weight was only part of the story. Sweeney admitted to eating stacks of protein shakes, burritos and Uncrustables the frozen jam-sandwich snack and putting her body into high-gear to match the fighter’s 135-to-137 pound fighting weight. One humorous anecdote involved co-star Ben Foster, who similarly bulked up for his role. She mistook his natural double chin for prosthetics around week two and teased him until he broke character.

But the physical wasn’t the only transformation. Representing Martin meant inhabiting the mindset of a woman who carved a path in a male-dominated sport while battling personal demons behind the scenes. “On a lot of different levels I understood and could relate to Christy,” Sweeney confessed. “She has her fight inside the ring and outside the ring … Misunderstood. Complicated relationships. Growing up as a woman.”

Sweeney’s career has not been without controversy. She referenced the backlash from a prior ad campaign for an American Eagle jeans commercial and a birthday photo scandal involving MAGA-style caps. “I’m always myself and what other people put on me is uncontrollable,” she said when asked about public perception. It’s a sentiment rooted in the duality of reinventing oneself for a role and preserving one’s own identity.

Directed by David Michôd and co-written with Mirrah Foulkes, Christy did more than showcase gritty fight scenes. At its core it delved into themes of coercive relationships, domestic abuse and identity terrain both intimate and indicting. The real Martin played an active role behind the scenes, ensuring the narrative of her near-fatal attack by her husband-trainer was handled with nuance. “She was there to tell her story,” Michôd said.

After completing the intense shoot, Sweeney had only seven weeks to drop the bulk and return as Cassie Howard on Euphoria. She described the transition as a “weird serotonin drop” and a mental reset after being in fighting mode for so long. At her peak for Christy, she felt “the strongest, full-of-life version of myself,” she said.

Yet for Sweeney, this project wasn’t about pushing Oscar buzz though the industry has taken notice but about honouring a story. “I did this for Christy. For me all that mattered was that she was happy with the film and that people get to see her story.”

Christy opened in the United States in November 2025 and is scheduled for a U.K. release later in the month. While audiences and critics may debate elements of the film, Sweeney’s commitment to the physical and emotional demands of the project has become part of its narrative.

Whether you’re inspired by the athletic dedication, intrigued by the narrative of female resilience in boxing, or interested in the cinematic transformation of a major star, Sweeney’s journey into the ring offers more than spectacle. It’s a reminder: true transformation often means getting punched, getting up and going back out there.