Eating a balanced and healthful diet is crucial for the normal functioning of all organ systems. Disordered eating habits (e.g., skipping meals) or prolonged dieting (e.g., calorie restriction) may deplete the body of important nutrients and can lead to malnutrition. In some cases, such habits may become chronic and may lead to the development of an eating disorder.

Eating disorders involve serious disturbances in eating behavior, including unhealthy reduction of food intake or severe overeating, in addition to extreme unhappiness or concern about body shape and weight. Oftentimes, individuals with eating disorders (e.g., anorexia nervosa, bulimia nervosa) associate their self-worth or self-esteem with the way their bodies look and attempt to control their weight through harmful methods such as starvation and purging (e.g., self-induced vomiting). In some cases, people may feel no self-control when it comes to food and may gorge themselves until they are uncomfortably full (binge eating).

Generally, eating disorders co-exist with other psychological disorders including depression, anxiety disorders (e.g., obsessive-compulsive disorder) and substance abuse. Females are more likely than males to develop eating disorders. According to the U.S. Department of Health and Human Services, more than 90 percent of patients with eating disorders are female. Eating disorders typically begin during adolescence or early adulthood. However, in some cases they may develop before adolescence as well as during middle age (at age 40 or older). Eating disorders are more common in industrialized, economically developed nations. Currently, between 1 and 4 percent of all young women in the United States have some type of eating disorder.