Anorexia Nervosa in adolescents holds adverse effects on different body systems as the cardiovascular, central nervous, endocrine, bone and gastrointestinal systems. There is paucity of information regarding the adverse effects of this tenacious illness on the lungs of adolescents at the hypocaloric stage of their illness. Based on previous clinical observations we postulate that lung function tests would be adversely effected by the hypocaloric nutrition of adolescents with anorexia nervosa and that they may improve during short refeeding in an inpatient setting of a general pediatric ward. To examine our hypothesis we would check lung function by various parameters of adolescents suffering from AN and a control group of adolescents.