Helen, a 17 year old, is an excellent student and very disciplined. she is 57, weighs 87 pounds and thinks she is fat. she denies any problems with her weight or severely limited food intake. she often wears baggy clothes to hide her body. recently her mother has noticed that she has lost hair and is no longer menstruating. her mother, now divorced from her father, is always on some type of diet. shes highly critical of helen, and her d2ecisions. helen most likely has which disorder?