Introduction:

Eating disorders are behavioral problems brought on by a complex interplay of factors, which may include emotional and personality disorders, family pressures, a possible genetic or biologic susceptibility, and a culture in which there is an overabundance of food and an obsession with thinness. There are four general categories of eating disorders:

• Bulimia nervosa
• Anorexia nervosa
• Binge eating
• Eating disorders not otherwise specified

These are not new disorders. Although anorexia nervosa was first defined as a medical problem in the late 1800s, descriptions of self-starvation have been found even in medieval writings.

Bulimia Nervosa

Bulimia nervosa is more common than anorexia, and it usually begins early in adolescence. It is characterized by cycles of bingeing and purging, and typically takes the following pattern:

• Bulimia is often triggered when young women attempt restrictive diets, fail, and react by binge eating. (Binge eating involves consuming larger than normal amounts of food within a 2-hour period.)
• In response to the binges, patients compensate, usually by purging, vomiting, using enemas, or taking laxatives, diet pills, or drugs to reduce fluids.
• Patients then revert to severe dieting, excessive exercise, or both. (Some patients with bulimia follow bingeing only with fasting and exercise. They are then considered to have non-purging bulimia.)
• The cycle then swings back to bingeing and then to purging again.
• Some studies have reported that patients with bulimia average about 14 episodes of binge-purging per week. To be diagnosed with bulimia, however, a patient must binge and purge at least twice a week for 3 months. (Some doctors believe that going through the cycle only once a week is sufficient for a diagnosis.)
• In some cases, the condition progresses to anorexia. Most people with bulimia, however, have a normal to high-normal body weight, although it may fluctuate by more than 10 pounds because of the binge-purge cycle.

Young people who occasionally force vomiting after eating too much are not considered bulimic, and most of the time this occasional unhealthy behavior does not continue beyond youth.

Anorexia Nervosa

The term "anorexia" literally means absence of appetite. Anorexia nervosa involves an aversion to food that leads to a state of starvation and emaciation. It is a very serious illness that some doctors believe is an entirely different condition from bulimia and should be not be diagnosed as a simple eating disorder.

Facts associated with anorexia nervosa:

• At least 15% to as much as 60% of normal body weight is lost.
• The patient with anorexia nervosa has an intense fear of gaining weight, even when severely underweight.
• Individuals with anorexia nervosa have a distorted image of their own weight or shape and deny the serious health consequences of their low weight.
• Women with anorexia nervosa miss at least three consecutive menstrual periods. (Women can also be anorexic without this occurrence.)

Patients with this condition are often characterized as anorexia restrictors or anorexic bulimic patients. Each type is equally prevalent.

• Anorexia restrictors reduce their weight by severe dieting.
• Anorexic bulimic patients maintain emaciation by purging. Although both types are serious, the bulimic type, which imposes additional stress on an undernourished body, is the more damaging.

Severe anorexia is common in the elderly, who may experience weight loss because of social isolation, impaired gastrointestinal function, or loss of certain chemicals related to the feeding drive. Such age-related anorexia, however, is not synonymous with anorexia nervosa, which is a psychologic disorder.

Binge Eating (Binge Eating Disorder)

Bingeing without purging is characterized as compulsive overeating (binge eating) with the absence of bulimic behaviors, such as vomiting or laxative abuse (used to eliminate calories). Binge eating usually leads to becoming overweight.

To be diagnosed as a binge eater, a person typically has the following characteristics:

• Bingeing at least twice a week for 6 months
• Consuming 5,000 - 15,000 calories in one sitting
• Eating three meals a day plus frequent snacks
• Overeating continually throughout the day, rather than consuming large amounts of food during binges

Since binge eating disorder is generally associated with weight gain, it will not be further discussed in this report. [For more information, see In-Depth Report #53: Weight control and diet.]

Eating Disorders Not Otherwise Specified

A fourth category called eating disorders not otherwise specified (NOS) has been established to define eating disorders not specifically defined as anorexia or bulimia. This category includes:

• Infrequent binge-purge episodes (occurring less than twice a week or having such behavior for less than months)
• Repeated chewing and spitting without swallowing large amounts of food
• Normal weight and anorexic behavior

Such patients tend to be older at diagnosis. Although less serious than other eating disorders, these patients still face similar health problems, including a higher risk for fractures and other conditions.