Actress Sydney Sweeney capped off months of dramatic physical transformation this week with the launch of her new lingerie brand, following a rapid weight gain and loss tied to an upcoming boxing biopic.
Sweeney, 28, gained approximately 35 pounds in late 2025 to portray legendary boxer Christy Martin in the film Christy, a role that required an intense physical overhaul.
Speaking at the time, the actress said she relied heavily on constant weight training, boxing sessions, and “protein shake after protein shake” to build muscle mass for the role.
Sweeney converted her grandmother’s backyard shed into a makeshift gym, training multiple times per day under the supervision of boxing and strength coaches.
The physical demands were significant, with Sweeney later revealing she suffered bloody noses and even a concussion while filming the fight scenes.
Once production wrapped, Sweeney quickly reversed course, losing more than 30 pounds in just seven weeks as she prepared for a slate of red carpet appearances and new projects.
In a recent interview, she said the rapid drop was driven by cutting out the extreme calorie intake, protein shakes, and creatine supplements used to build mass.
“When you stop working out and taking all your protein shakes, you lose muscle super fast,” Sweeney explained, noting that muscle was the first weight to come off.
The actress debuted her slimmer figure at the 2025 GQ Men of the Year event, where she was named Actress of the Year and wore a vintage crushed velvet Versace gown.
The look marked the beginning of a high-profile run of public appearances, including the Governors Awards and premieres for her upcoming film The Housemaid.
At those events, Sweeney leaned into classic Hollywood glamour, wearing plunging gowns, corseted silhouettes, and feathered accents inspired by icons like Marilyn Monroe and Pamela Anderson.
Her evolving public image coincided with the rollout of SYRN, a lingerie brand she announced on social media ahead of its Jan. 28 launch.
In promotional photos released for the brand, Sweeney showcased a range of lingerie styles designed to accommodate different body types, per Fox News.
“I was in the 6th grade with DDs. I hated the bra I had to wear,” Sweeney said in a statement, explaining the personal motivation behind the brand.
She said her goal with SYRN was to design lingerie that fits “all bodies” and reflects the many roles women occupy in their daily lives.
“I wanted to create a place where women can move between all the different versions of who we are,” Sweeney said, emphasizing versatility and comfort.
The actress added that lingerie can be both empowering and private, allowing women to express femininity on their own terms.
The launch of SYRN marks Sweeney’s latest expansion beyond acting, capping a period defined by physical extremes, red carpet visibility, and a new business venture.
