The actress was released from rehab earlier this year after seeking help with bulimia, bipolar disorder, and self-harm.
Talking to People, she opened up about the horrifying details of her illness.
'When I was about 15, I was only eating two meals a week, but I wasn't losing any more weight because my body adjusted to that. So I tried new things: laxatives, fasts - nothing was working,' said the 18-year-old.
'I decided maybe I should start throwing up. At my worst, I was doing it five times a day. I threw up so hard and so much, it was just blood in the toilet.'
But her world came crashing down in November when she suffered a breakdown and had to pull out of her world tour with the Jonas Brothers.
'My eating disorders have ruined my life. I thought I could control it, but I couldn't. I ended up in treatment at the most untimely moment in my life,' she explained.
Since leaving rehab, she has been making steady progress, but said that it still isn't easy.
'It is more difficult now because I don't have people supervising me. That's why I haven't been working,' she said.
'My goal for every day is to eat three meals, and that's challenging enough. There are days when I feel so overwhelmed, like I can't do it... I'm still learning just to like food... I'm determined to fight this. I've never been more peaceful or happy in my life. What's important is to help others get to this place.'
