When a four year old was nervous about dressing up as a princess to see Cinderella, her 25 year old uncle, Jesse Frank Nagy, dressed as a princess as well to give her confidence. "If it's going to make her happy, I'll do it," he said. Just look at her face-
Then at the bottom of that article, these images of Disney Princesses with realistic waistlines:
(Hmm..maybe to this collection we could add Lily James in the Cinderella costume in the movie, with and without a restricting corset in which she was unable to eat solid foods?)
I should note that in Hollywood, it's considered completely normal for many actors (of both genders) to diet severely for a part, especially one with a particularly revealing costume or if the character is supposed to be especially thin. It's not something that's limited to Disney movies, but something that is of concern across the board where media is concerned.