How 'Cats' Star Rebel Wilson Lost 8 Lbs In Four Days

As if you needed another reason to go see "Cats" this winter, it may provide a way to shed those extra holiday pounds -- just ask Rebel Wilson.

The 39-year-old actress chatted with Entertainment Tonight on Thursday and revealed she lost eight pounds while working on the film. The key to her unintentional weight loss? Dancing in a hot room.

"I lost eight pounds, shooting my number, in four days," Wilson recalled. "One, because there's a lot of physicality... but also, they heated up the set very high, to almost 100 Fahrenheit, so that we could never cool down."

"These people are like, the best dancers in the whole world, so they can't cool their muscles down or they could get an injury and they'd be out of the film... So they'd heat up the set like a sauna so we would never cool down, but made it pretty uncomfortable," she explained.

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While it wasn't part of Wilson's job, in particular, it is a pretty common practice that actors will lose or gain weight for a role. A major example of this is Christian Bale. The award-winning actor's weight has fluctuated for his roles in films like "American Psycho," "The Machinist," and, most recently, "Ford v Ferrari."

Despite winning awards for some of these roles, fans shouldn't expect any drastic weight changes from Bale in the future.

“I keep saying I am done with it. I really think I am done with it, yeah,” Bale said.

"Cats" hits theaters on Dec. 20.