is significantly low, and variations in deve lopmental trajectories among youth limit the
utility of simple numerical guidelines. The CD C has used a BMI-for-age below the 5th per-
centile as suggesting underweight; however,  children and adolesce nts with a BMI above
this benchmark may be judged to be significantly underweight in light of failure to main-
tain their expected growth trajectory. In su mmary, in determining whether Criterion A is
met, the clinician should consider available numerical guidelines, as well as the individual’s
body build, weight history, an d any physiological disturbances.
Individuals with this disorder typically display an intense fear of gaining weight or of
becoming fat (Criterion B). This intense fear of becoming fat is usually not alleviated by
weight loss. In fact, concern about weight gain  may increase even as weight falls. Younger
individuals with anorexia nervosa, as well as  some adults, may not recognize or acknowl-
edge a fear of weight gain. In the absence of  another explanation for the significantly low
weight, clinician inference drawn from collateral history, observatio nal data, physical and
laboratory findings, or longitudinal course eith er indicating a fear of weight gain or sup-
porting persistent behaviors that prevent it  may be used to es tablish Criterion B. 
The experience and significance of body weight and shape are distorted in these indi-
viduals (Criterion C). Some individuals feel globally overweight. Others realize that they
are thin but are still concerned th at certain body parts, partic ularly the abdomen, buttocks,
and thighs, are “too fat.” They may employ a variety of techniques to evaluate their body
size or weight, including frequent weighing, obsessive measuring of body parts, and per-