Eating disorders happen as a result of severe disturbances in eating behavior, such as unhealthy reduction of food intake or extreme overeating. These patterns can be caused by feelings of distress or concern about body shape or weight and they harm normal body composition and function. A person with an eating disorder may have started out just eating smaller or larger amounts of food than usual, but at some point, the urge to eat less or more spirals out of control.
Eating disorders are very complex, and despite scientific research to understand them, the biological, behavioral and social underpinnings of these illnesses remain elusive. Eating disorders frequently develop during adolescence or early adulthood, but some reports indicate their onset can occur during childhood or later in adulthood. Many adolescents are able to hide these behaviors from their family for months or years.
Eating disorders are not due to a failure of will or behavior; rather, they are real, treatable medical illnesses in which certain maladaptive patterns of eating take on a life of their own. The main types of eating disorders are anorexia nervosa and bulimia nervosa. A person with anorexia nervosa starves himself or herself to be thin, experiencing extreme weight-loss. An estimated .5 to 3.7 percent of females suffer from anorexia nervosa in their lifetime. Bulimia nervosa is binge eating followed by purging (vomiting). An estimated 1.1 percent to 4.2 percent of females have bulimia nervosa in their lifetime. A third disorder, binge-eating disorder, is characterized by frequent episodes of out-of-control eating. A cycle develops due to feelings of shame and disgust caused by obesity brought on by the overeating and leading to bingeing again. Community surveys have estimated that between 2 percent and 5 percent of Americans experience binge-eating disorder in a six-month period. This illness has only been suggested but has not yet been approved as a formal psychiatric diagnosis.