From Celebuzz:
Demi's rep confirmed that the starlet checked into a treatment center this weekend for "emotional and physical issue." According to People, the young Disney star had battled problems with eating disorders and cutting in the past.
"While we cannot speak to any specific case or Demi Lovato’s health, we can assure the public that people do get well from eating disorders, especially if they are motivated to do so," Lynn Grefe, the CEO of National Eating Disorders Association, told Celebuzz, "Cases vary, and the longer a person struggles the harder it can be to recover, but gratefully most do get well if they receive appropriate treatment."
According to People, Demi had often had issues dealing with her weight. "She definitely had body-image issues," and insider tells the magazine, "She was always conscious of her weight."
The 17-year-old star also told the magazine that her "You Make Me Beautiful" tattoo on her rib was meant to remind her of the help she had when she had self-image issues.

Many sources say Demi is doing great in treatment, but they are not saying when she will be released.

Cody Linely, Demi's ex, dedicated this YouTube video to her.