Sydney Sweeney is opening up about her dramatic transformation to portray legendary boxer Christy Martin in an upcoming biopic. In a new interview with W Magazine published Monday, the actress revealed she spent months training for the role, gaining 30 pounds and going up four pant sizes in the process.

The Emmy nominee revealed that “my body was completely different” because of all the training, which led to her not being able to “fit in any of my clothes.”

Fans went wild last fall when paparazzi captured some photos of Sydney Sweeney looking very much unlike Sydney Sweeney while filming an upcoming movie. Now, the actress is giving more details about her upcoming Christy Martin biopic—and the physical work it took for her to get into