Demi Lovato Says Eating Disorder Started At Age 8, Cutting At Age 11

Demi Lovato says the issues that eventually led her to seek treatment started as a child.

During her first interview since leaving rehab, Demi tells ABC's Robin Roberts that "I was compulsively overeating when I was eight years old. So, I guess, for the past 10 years I've had a really unhealthy relationship with food."

Lovato also revealed that she's been a cutter since age 11. "It was a way of expressing my own shame, of myself, on my own body," she said in the interview. "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."

Demi also says she takes "full responsibility" for striking backup dancer Alex Welch. "I feel horrible," Lovato says. "[She] was my friend."

Her full interview airs Friday on 20/20.

As for what's next for Lovato work-wise? See what she just announced regarding her Disney show ... after the jump.