There are three essential features of anorexia nervosa: persistent energy intake restriction;
intense fear of gaining weight or of becoming fat, or persistent behavior that interferes
with weight gain; and a disturbance in self-perceived weight or shape. The individual maintains
a body weight that is below a minimally normal level for age, sex, developmental trajectory,
and physical health (Criterion A). Individuals' body weights frequently meet this
criterion following a significant weight loss, but among children and adolescents, there
may alternatively be failure to make expected weight gain or to maintain a normal developmental
trajectory (i.e., while growing in height) instead of weight loss