Eating disorders can profoundly affect the individual and family unit. Changes in the individual include disturbances in body perception, organ damage, and increased risk factors leading to ill-health in later years. There is thus a fundamental requirement to adequately diagnose, treat and manage those individuals with eating disorders which the American Psychiatric Association have recently categorized (DSM-5) into Anorexia Nervosa, Bulimia Nervosa, Binge Eating Disorder, and Other Specified- and Unspecified-Feeding or Eating Disorders. The aim of this reference work is to describe, in one comprehensive resource, the complex relationships between eating disorders, diet, and nutrition. In this regard eating disorders are regarded as psychiatric conditions though there are some eating disorders that have a genetic basis. Genetic influences will also include polymorphisms.