Anorexia nervosa is a severe cause of undernutrition. It leads to a dramatic decrease of weight with an important modification of the body composition. During the renutrition phase, disharmonious body composition recovery is a relapse factor. Dual X-ray absorptiometry (DXA) is the gold standard to study body composition in children with anorexia nervosa. But, due to technical limits, DXA analysis needs to take in account a potential failure to thrive with an adjustment on height. Moreover DXA needs an irradiation which does not allow close repeat measurements. Since several years, a simple, non-invasive, non-irradiant method for measure of body composition has been developed in pediatrics: the air displacement plethysmography (ADP). Actually, only one device is available for this measurement: the BodPod®. However, feasibility and accuracy of ADP compare to DXA have not been evaluated in pediatric anorexia nervosa. The aim of this study is to compare the accuracy of BodPod® compare to DXA in girls with anorexia nervosa.

Inclusion Criteria:

• Female patients aged between 8 and 18 years
• Female with a diagnosis of anorexia nervosa according to the DSM V classification, restrictive type or hyperphagic / purgative access type, evolving for less than 3 years.
• Female who received explanations adapted to their level of understanding for this study
• Female who expressed their consent to participate to this study
• Female whose parents or holders of parental authority have been informed and signed free and informed consent
• Female affiliated to a social security scheme

Exclusion Criteria:

• Patients with psychotic symptoms
• Patients with claustrophobia
• Patients with severe respiratory disease