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"Hills" star Stephanie Pratt opens up for the first time in the new issue of Us Weekly about hating her body and her terrifying secret struggle with bulimia -- sparked, she says, by the pressure of appearing alongside her super-thin friends on the hit MTV reality show.

The 5-foot-7 23-year-old reveals she began bingeing and purging after watching a scene she shot with Lauren Conrad in 2007 after first joining the cast: "I was horrified. I remember saying, 'I can't believe how huge I look walking over to Lauren.'"

Another time, when filming in Hawaii in bikinis, the size 0-2 Pratt -- in a bikini and cover-up -- asked co-star Audrina Patridge, "What looks better: Shirt on or off?" Patridge said, 'On.'" Says Pratt, "The producers never put pressure on us to lose weight," but she adds, "It's embarrassing working with skinny girls."

The new issue of Us Weekly hits stands today.


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