Demi Lovato's first TV interview since entering a treatment facility late last year airs this Friday on Good Morning America and 20/20. The 18-year-old sat down with Robin Roberts to open up and get personal about many of the issues she faced.
According to ABC, "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," Lovato 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."
"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.
"I was compulsively overeating when I was eight years old," she said. "So, I guess, for the past 10 years I've had a really unhealthy relationship with food."
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: According to Demi, at age 11, she began cutting herself - intentionally self-mutilating her wrists as a way of coping with emotions.
"It was a way of expressing my own shame, of myself, on my own body," she told Roberts.
"I was matching the inside to the outside. And there were some times where my emotions were just so built up, I didn't know what to do. The only way that I could get instant gratification was through an immediate release on myself."
Lovato's family and management team held an intervention after an incident with backup dancer Alex Welch on the Camp Rock 2 tour.
"They sat me down and said, ';You can't live like this,'" Lovato said.
She immediately quit the tour and checked in to Timberline Knolls - a residential treatment center in Illinois for women battling addiction and eating disorders.
While in treatment, Lovato learned to alter her coping skills and found better ways to deal with her emotions.
"For the first time in my life, I started to feel," she said.
During the tough times in treatment, Lovato says it was the thought of her younger sister, Madison, who plays Juanita Solis, the daughter of Gabrielle on "Desperate Housewives," that got her through her darkest hours.
"A picture of my little sister, on my little bulletin board, was one of the main things that kept me going," she said. "I just kept thinking, ';OK, set this example for your little sister.'"
Lovato wanted to set an example - not only for Madison, but for all the other women fighting the same issues.
"The real reason why I'm sitting down with you," she said, "is to open up the eyes of so many young girls, that it doesn't have to be this way."
Make sure to watch the full interview Friday at 10pm on 20/20 and also that morning on Good Morning America to hear Demi tell her story.