Demi Lovato has admitted that her life was once so out of control that she didn’t think she would make it to 21.

The singer and actress – who battled substance abuse, self-harming, an eating disorder and depression before ending up in rehab – told American Way magazine that she used to self-medicate with booze and drugs.

“I lived fast and I was going to die young,” she said.

“I didn’t think I would make it to 21.”

Demi Lovato on stage
Demi Lovato (Greg Allen/AP/PA)

In 2010, at the age of 18, Demi checked into rehab where she was diagnosed with bipolar disorder and treated for bulimia.

She recalled: “So now I’m in rehab and I thought, ‘Oh great, now the world thinks I’m just another stereotype’.”

The Skyscraper singer’s mental illness and eating disorder were treated but she said her substance abuse wasn’t under control.

“I thought, ‘I’m not in treatment for a drug and alcohol problem’,” she explained. “But once I started eating again, the other issues got worse. It was like whack-a-mole.”

Demi later entered a sober house for around a year, and is now clean.

“I didn’t go into treatment thinking, ‘OK, now I’m going to be an inspiration’,” she said. “At times I was resentful for having that kind of responsibility, but now, it’s really become a part of my life. It holds me accountable.”