Eating disorders are illnesses marked by extreme eating behaviors (e.g., excessive overeating or food restriction) or considerable concern about body weight or shape. Individuals with eating disorders have significant distress or impaired daily functioning. Eating disorders, which usually begin during adolescence, are categorized by three types: anorexia nervosa, bulimia nervosa and eating disorders not otherwise specified.
Anorexia Nervosa
According to the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM), anorexia nervosa is characterized by low body weight and the refusal to maintain a healthy body weight. Individuals with anorexia nervosa also have an intense fear of gaining weight or of being overweight and usually strive to be thinner despite being underweight. They have a poor body image and typically base their self-worth on weight or body shape. Those with anorexia usually see themselves as fat and may deny being at a low weight even though they may be emaciated and thin. Females experience an absence of their menstrual cycle.
There are two types of anorexia nervosa. In the restricting type, individuals limit food intake (such as eating only 500 calories a day). The binge-eating/purging type is marked with behaviors to remove food from the body in an attempt to prevent weight gain. Examples of purging behaviors include self-vomiting and using laxatives, enemas or diuretics. Anorexics who binge and purge typically binge on a small amount of food and purge regularly.
Bulimia Nervosa
Bulimia nervosa is distinguished by a repetitive cycle of feeling out of control when eating an unusually large amount of food (binge eating) and using behaviors to compensate for the binge eating and possible weight gain, according to the DSM. There are two types of these compensatory behaviors. In the purging type, the individual vomits or uses laxatives, enemas or diuretics, and in the non-purging type, the individual fasts or exercises excessively.
This binge-and-purge cycle must occur at least twice a week for at least three months for a diagnosis of bulimia nervosa. Similar to anorexia nervosa, those with bulimia base their self-worth on weight or body shape. But unlike anorexia nervosa, individuals with bulimia are not underweight and may be of a healthy weight or overweight.
Eating Disorder Not Otherwise Specified (EDNOS)
As noted by the DSM, a diagnosis of EDNOS is made when a person has extreme eating behaviors but does not meet full criteria for anorexia nervosa or bulimia nervosa. For example, a female might meet all criteria for anorexia nervosa but has not lost her menstrual cycle. Another example is if an individual meets all criteria for bulimia nervosa but the binge-purge cycle occurs less than once a week. Binge eating disorder is in the EDNOS category. In binge eating disorder, an individual regularly binge eats without using the compensatory behaviors found in bulimia nervosa. EDNOS is the most frequently diagnosed eating disorder.
References
- "Biological Psychiatry"; Research on Eating Disorders: Current Status and Future Prospects; Benedetto Vitiello and Israel Lederhendler; May 2000
- "Diagnostic and Statistical Manual of Mental Disorders (4th ed. Text Revision)"; American Psychiatric Association; 2002
