Sydney Sweeney Details How She Became ‘Crazy Strong’ for Her Upcoming Christy Martin Biopic

Sydney Sweeney didn’t just learn to throw a jab for her upcoming Christy Martin biopic—she also rebuilt her physique. In a new W Magazine cover story, the 27-year-old recalls signing on to play the famous boxer and immediately embracing a fighter’s schedule: “I loved it. I came onboard to play Christy, and I had about three and a half months of training. I started eating. I weight-trained in the morning for an hour, kick-boxed midday for about two hours, and then weight-trained again at night for an hour.”

All that work added over 30 pounds, and change in her wardrobe. “My body was completely different. I didn’t fit in any of my clothes. I’m usually a size 23 in jeans, and I was wearing a size 27. My boobs got bigger. And my butt got huge. It was crazy!” Still, the payoff was worth it: “I was so strong, like crazy strong.”

Director and co-writer David Michôd was equally struck by her commitment. “Sydney trained her butt off to play the part...She turned up to work every day with her tail wagging, ready to go. No matter how tough it was, she was like a ray of sunshine,” he told the magazine.

That transformation, however, vanished almost as quickly as it arrived. Michôd recalled FaceTiming Sweeney seven weeks after wrap, when she was back in the Euphoria makeup trailer: “I was stunned by the change in her appearance,” Michôd said. “I had only seen her as an adorable, tough moppet with late-’80s hair, ready to box. Sydney was happiest when she was in the ring punching and being punched. It was shocking to see her being so glamorous.”

The intense regimen revived an old passion for the actress. “My mom told me from a very young age to fall in love with as many things as possible,” Sweeney said, listing skiing, wake-boarding, grappling, and kick-boxing among the sports she took up before acting took over.

Production on the still-untitled film has wrapped, and Sweeney is already helping introduce it to fans: On June 8, she rode alongside Martin as grand marshal of the International Boxing Hall of Fame’s Parade of Champions in Canastota, New York.