The Oscar-winning actor stars as tennis icon Billie Jean King in her latest on-screen role, which centres on King's famous match against male player Bobby Riggs in 1973, reported Entertainment Tonight.
Asked how she went about bulking up for the role, she said, "A lot of weightlifting, a lot of protein shakes. I never did it before and I loved it."
The 28-year-old actor said she initially struggled to cope up with the physical demands of adding the extra muscle.
But soon got used to her workout regime and eventually started enjoying the challenge.
Steve Carell plays the role of Riggs in the new movie, which marks the first time he has worked with Stone since he starred as her father in 2011's "Crazy Stupid Love".