More than the weight per se is the dramatic weight loss and the behaviors that surround her eating habits, along with the medical worries. Seeking help is not up to her - it's important that you arrange help. Enlist the assistance of her pediatrician in this regard. Serious medical complications, including death, can arise from anorexic behavior and it is mandatory that she be treated.
She has some symptoms.Is she 5'9" and 102lbs, underweight too much in her age? Thank you.
I should have mentioned that her weight (in terms of percentile for her age) is not alarming. I'm assuming that when she lost weight she was actually overweight at the time. Is that correct?
When you say that she displays many symptoms of anorexia (in spite of eating three meals/day), what do you mean? What are the symptoms you are noticing?