Eating disorders are defined as eating habits that are harmful to an individual's health and involve issues with food and weight. The three most common types are anorexia nervosa, bulimia nervosa, and binge eating disorder. Anorexia is characterized by self-starvation and fear of weight gain. Bulimia involves cycles of binge eating and purging. Binge eating disorder involves periods of uncontrolled eating beyond fullness. All eating disorders can have serious medical and psychological effects if left untreated.