(NEW YORK) -- After checking into treatment at a residential facility, teenage Disney darling Demi Lovato received a shocking diagnosis: she was bipolar.
"I had no idea that I was even bipolar until I went into treatment," the 18-year-old told ABC News. "I was actually manic a lot of the times that I would take on workloads, and I would say, yes, I can do this, I can do this, I can do this. I was conquering the world, but then I would come crashing down, and I would be more depressed than ever."
Lovato, who recently announced she was leaving her hit tween comedy, Sonny with a Chance, to focus on her music career, sang her way to the top of the pop charts and heights of wholesome teen icon status, but her natural outward confidence in front of the camera could not protect her from the inner, lasting effects of childhood bullying.
"I've spoken openly about being bullied throughout the past few years, but one thing that I've never been able to feel comfortable talking about was the effects that it had on my life, afterwards," she said. "I literally didn't know why they were being so mean to me. And when I would ask them why, they would just say, 'Well, you're fat."
Her torment turned into a dangerous habit.
"I developed an eating disorder, and that's kind of what I've been dealing with ever since," she said.
Lovato began a lifelong struggle with bulimia and alternately, severely restricting her eating.
Her family helped her find professional help for her food issues. But there was a secret battle she fought alone, something she desperately hid from everyone: At age 11, Lovato began cutting herself -- intentionally self-mutilating her wrists as a way of coping with emotions. It was a dangerous coping mechanism that continued throughout her teen years.
Last summer, it all came to a boiling point during her concert tour with the Jonas Brothers for the Disney Channel musical, Camp Rock 2.
"I was performing concerts on an empty stomach," she said. "I was losing my voice from purging. I was self-medicating. I was not taking medication for depression, and I literally was so emotionally whacked out that I took it out on someone that meant a lot to me."
Lovato admitted to physically striking one of her backup dancers, Alex Welch, during the South American leg of their international tour. Lovato's family and management team then held an intervention.
She immediately quit the tour and checked in to Timberline Knolls -- a residential treatment center in Illinois for women battling addiction and eating disorders -- where she was diagnosed as having bipolar disorder.
While in treatment, Lovato learned to alter her coping skills and found better ways to deal with her emotions.
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