Sydney Sweeney slams online body-shamers as she transforms herself for role as professional boxer

"Nothing to see here other than an average chunky Yankee girl," one user wrote. 

"Too pale," another wrote. "And she needs to lose a few pounds around the middle."

Towards the end of the video, Sweeney shared footage of herself working out in the gym, lifting heavy weights, and training in a boxing ring.

At one point, the video pans to a sign that reads, "Just Don't Quit."

Many were quick to praise Sweeney's clap back. 

"It's always wild to see people publicly out-themselves as pieces of s---with comments like that," Lili Reinhart wrote. "You look incredible and your dedication to your project is very inspiring."

"Strong baddie," Kesha added.

Sweeney's latest role as professional boxer Christy Martin has left her unrecognizable. In a recent Instagram post, Sweeney posed in costume alongside the real Martin with both of them holding up a fist.

"We have wrapped filming Christy Martin's story and it has been one of the most emotional, transformative experiences of my life. Christy's journey is so deeply inspiring, and having her by my side during this process was nothing short of surreal," she wrote in the caption.

She continued, "There were moments on set where I'd glance over at her standing by the monitors, cheering us on, and I'd just become so emotional. Knowing what she's endured, what she's pushed through to be there in that moment-it made me want to cry."

Throughout the rest of the caption, Sweeney thanked the cast and crew of the movie, later adding she is excited for audiences to "witness a story that's as powerful as the woman who lived it."

Fox News Digital's Brie Stimson contributed to this post.