Sydney Sweeney details preparation to play female boxer

At yesterday's premiere of "Christy," a gritty biopic of US female boxing pioneer Christy Martin, the film's star Sydney Sweeney declined to address her recent jeans ad controversy that caused a firestorm online.

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But she was prepared to talk about her waistline, namely how she gained weight to transform her appearance for a role that could make her an Academy Award contender.

"A lot of Chick-fil-A, a lot of Smucker's, a lot of milkshakes, a lot of protein shakes," Sweeney told an adoring crowd following the world premiere at the Toronto International Film Festival. "I trained three times a day, every day."

The film recounts a life that director David Michod described as incredible. "Particularly incredible that I'd never heard it before" until working on the film, he said after the premiere.