The High School Musical star plays a member of a group of female inmates, alongside Abbie Cornish and Jena Malone, who try to break out of an asylum in the forthcoming film.
Hudgens trained with a team of experienced Navy officers for the role, but she admits the actresses all ditched their diets once they began filming the dramatic scenes.
She tells Britain’s Total Film magazine, “Some of the scenes were really intense. I haven’t done that much heavy drama before and some scenes were just so draining.
“We would all be a total disaster afterwards and cheat on our diets together and eat cake to comfort ourselves.”