Demi Lovato believes she was ''born'' with an eating disorder.

The 19-year-old singer-and-actress - who checked into rehab in October 2010 to receive treatment for self-harm and bulimia- can't remember ever having a normal relationship with food and has always been plagued with thoughts about being too fat.

She said: ''I think I was born with an eating disorder, because I've never had a relationship with food that was normal.

''I remember looking in the mirror with nappies on thinking, 'You're fat, change it'.

''II started overeating when I was about eight; I was a binge eater. I would bake a whole plate of cookies and eat them all. Then when I turned 12 I was bullied in school and they called me fat. I went from being an overeater to stopping eating and I lost about 30lb. From then on I continued undereating, but my weight plateaued.

''[Then] I started throwing up to lose weight.''

Demi also revealed she started self-harming when she was 12 years old and admits to ''self-medicating'' with DRUGS and alcohol.

She added in an interview with You magazine: ''I started when I was 12, when I was bullied. It was my way of dealing with the stress and then I often resorted to it when I was feeling overworked.

''Girls [who self-harm] scratch or cut themselves with razor blades, scissors or sharp objects, or burn themselves. I've pretty much tried all of it. My main thing was cutting and that was so horrible.

''I definitely self-medicated with drugs and alcohol. I would be lying if I said I didn't.''

Though Demi is now focused on her recovery, she is aware that she will be fighting her problems for the rest of her life.

She added: ''There's definitely temptation - every meal I fight it. It's an addiction and I'm going to have to fight it for the rest of my life.

''There's no cure and I may mess up, but I want to be a better role model for my fans and my younger sister.''