updated 06/15/2011 AT 9:50 AM ET
•originally published 06/19/2011 AT 9:50 AM ET
Paris Hilton is the first to admit that her teens and 20s were all about fun, not food.
“I’d been to every incredible party in the world,” says Hilton, 30. “But I was going out with my girlfriends and dancing, having a lot of coffee and Red Bull. Being on the go, I would just grab fast food or skip meals because I was busy.”
But that lifestyle drained her body and by last year, the 5’8” Hilton weighed just 105 pounds and fit into a size zero.