Demi Lovato: 'Rehab was like prison'

X Factor USA judge Demi Lovato has opened up about her treatment for an eating disorder, saying that therapy felt like "a prison".

The star told talkshow host Katie Couric that coming to terms with her imposed surroundings was "so difficult at first".

I remember walking around saying 'I'm in prison!'" she revealed during an interview for Katie, which airs on Monday (September 24).

"They needed to have those strict rules in order for me to understand how sick I was. I wasn't allowed to use the bathroom by myself.

"We had specific phone times. There are tons of things you weren't allowed to have; you weren't allowed to have certain hair products or whatever that you could injure yourself with or possibly drink and you were just stripped of a lot of things."

Lovato - who has spoken out about her struggles with self harm and her diagnoses of bipolar disorder and bulimia - admitted that mealtimes posed the biggest challenge during her recovery.

"I also had someone watching over me every single time I ate," she said. "If I didn't finish what was on my plate - and often... I would cry because I physically couldn't stomach it - if that happened I would have to have little consequences.

"Nothing horrible, just not being able to go to the cafeteria to eat."