Demi Lovato’s coming clean: It was an eating disorder that prompted her three-month stint in rehab late last year.

The Sonny With a Chance actress, 18, set off a Tween Panic when she abandoned her tour with The Jonas Brothers and checked into a private facility in Chicago to receive treatment for “emotional and physical issues” last October. She even attacked one of her backup dancers in a fit of rage. But, as a contributor in the May 2011 edition of Seventeen Magazine, now alludes to the real reason she entered rehab. In the piece, Lovato says that for years she suffered for silence with a “lifelong disease,” but is now coping well, thanks to treatment.

“I wish I could tell every young girl with an eating disorder, or who has harmed herself in any way, that she’s worthy of life and that her life has meaning. You can overcome and get through anything,” Demi now says. “Yes, there have been times when I definitely have been tempted to get rid of my dinner. But I will deal with it for the rest of my life because it’s a life-long disease. I don’t think there’s going to be a day when I don’t think about food or my body, but I’m living with it, and I wish I could tell young girls to find their safe place and stay with it.”

Demi, who is reportedly now dating the much-older Wilmer Valderamma, urges girls with eating disorders to turn to loved ones for help, saying: “If you are going through that dark period, go to your family and closest friends. Don’t put yourself in danger. It’s very crucial that you get your feelings out – but don’t ever inflict harm on your own body because your body is so sacred.”

In February, just weeks after her release from rehab, Demi issued a video statement thanking her fans for their unwavering support.

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