Corset training is all the rage in Hollywood as a slimming fad, but as a costuming choice?

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Cinderella star Lily James has come under fire in recent weeks for her tiny waistline in the Disney movie and promotional materials. Critics are crying Photoshop, but the actress claims that it’s her natural slim look, with the aid of a corset.

"I naturally have a really small waist and then the corset pulls it in and the skirt makes it bigger so I think the perspective makes it look even smaller," James told ET correspondent Jason Dundas at Sunday’s premiere in L.A. "But it's totally just my waist. There's no CGI."

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James told Dundas she wore a corset under every dress in the film, but costumers were especially conscious of creating a silhouette in Cinderella’s iconic blue ballgown. Her co-stars also support her corset claims.

"Oh my God, she, she could barely breathe when she was dancing that waltz with the Prince," said Cate Blanchett, who plays James’ evil stepmother Lady Tremaine in the film. "It was remarkable."

Judge for yourself and watch the latest Cinderella trailer in the video below.