Anorexia nervosa (AN) and bulimia nervosa (BN) are disorders characterized by aberrant patterns of feeding behavior and weight regulation and disturbances in attitudes and perceptions toward body weight and shape. The distinguishing features of AN are an inexplicable fear of weight gain, unrelenting obsession with fatness, and extreme cachexia, to which the person appears strikingly indifferent. In BN, the differentiating characteristics are binge eating of variable frequency and intensity, usually emerging after a period of dieting and which may or may not have been associated with weight loss, and either self-induced vomiting or some other means of compensation for the excess of food that is consumed. Unlike in AN, weight does not decrease to dangerously low levels. In most people affected with BN, feeding patterns are disrupted and satiety may be impaired. However, although abnormally low body weight is an exclusion for the diagnosis of BN, a significant proportion of persons affected with this illness have a prior history of AN (Eddy et al. 2007).