Overconsumption of food has led to an increase in the incidence of obesity, non-insulin-dependent diabetes mellitus, hypertension, cardiovascular diseases, and eating disorders. This chapter familiarizes professionals with the clinical picture and the medical and endocrine consequences of the two eating disorders. Historical records have shown that prolonged food abstinence severe enough to induce significant weight loss, such as religious fasting in the middle Ages or chronic infectious and gastrointestinal diseases, the latter common among women in the late 19th century, can precede the psychological and behavioral symptomatology of anorexia nervosa (AN). Pathologic weight loss leading to a starved and eventually skeleton-like appearance is the hallmark of AN. Bulimia nervosa (BN) is an eating disorder characterized by episodic binge eating most often followed by vomiting. BN develops in adolescents or young women who aspire to a lower than normal ideal weight but has difficulty dieting.