Stephanie Pratt, star of MTV’s smash hit The Hills, has revealed that she is suffering from an eating disorder.

In the new issue of Us Weekly, the younger sister of series villain Spencer Pratt reveals that it was being on the reality show that drove her to start bingeing and purging.

The 5-foot-7 Stephanie says she became bulimic after watching a scene she shot with former series heroine Lauren Conrad, just after joining the cast in 2007: “I was horrified. I remember saying, ‘I can’t believe how huge I look walking over to Lauren.’”

The 23-year-old says the show never put pressure on her to lose weight, but added that “it’s embarrassing working with skinny girls.”