Eating Disorders: Overview and Risk Factors
Anorexia nervosa and bulimia nervosa are common and serious eating disorders. Up to 3 percent of American women suffer from an eating disorder, and up to 20 percent of college-aged women engage in abnormal eating behaviors.
Anorexia nervosa is marked by refusal to maintain normal body weight. Affected individuals have a distorted body image, a body weight at least 15 percent below the expected value, absence of menstrual periods, and abnormal eating behaviors, particularly restricted food intake. About half of patients also have symptoms of bulimia.
Bulimia nervosa is a disease marked by recurrent episodes of binge eating and inappropriate methods to prevent weight gain, such as self-induced vomiting and laxative abuse.
The cause of these disorders is largely unknown, but genetic, psychological, environmental, and social factors are probably involved. Some experts believe that a cultural obsession with thinness and dieting in the United States and other Western countries has set the stage for eating disorders. However, equally likely is that poor dietary habits in Western countries frequently lead to weight gain among children and adolescents. Rather than adopt more healthful dietary habits, many young people turn to dietary restriction or other means to control their intake. Nearly 40 percent of adolescent girls in the United States believe they are overweight, and nearly 60 percent are attempting to lose weight. A substantial number have reported that they have tried vomiting or laxatives to control their weight.
The long-term health issues associated with eating disorders include osteoporosis, damage to certain areas of the brain, electrolyte imbalances, heart disorders, intestinal dysfunction, wearing down of the teeth, and infertility, some of which are irreversible, even with appropriate treatment. Many affected individuals also have other psychiatric disorders, including depression, anxiety, and obsessive-compulsive disorder.
About 90 percent of cases occur in women, usually beginning in late adolescence and early adulthood. Additional risk factors include:
- History of obesity and/or dieting: A history of obesity is linked to an increased risk for eating disorders. Adolescents who reported dieting during mid-adolescence were significantly more likely to develop eating disorders.
- Participation in activities that emphasize leanness: Examples include ballet, gymnastics, and running.
- Family history: Women who have a first-degree relative with an eating disorder are up to 10 times more likely to develop an eating disorder themselves. Eating disorders are also associated with a family history of depression.
- Psychiatric history: Depression, substance abuse, sexual abuse, weight dissatisfaction, and low self-esteem are linked to a higher risk for eating disorders.
- Early puberty: Early sexual development may lead to increased self-consciousness regarding body image and is associated with subsequent dieting behaviors.
A medical and psychiatric history and physical examination is necessary, with the diagnosis based on criteria developed by The American Psychiatric Association.
The American Psychiatric Association's diagnostic criteria for anorexia nervosa are summarized as follows:
- Refusal to maintain body weight at or above a minimally normal weight for age and height (e.g., weight loss leading to maintenance of body weight less than 85 percent of that expected; or failure to make expected weight gain during period of growth, leading to body weight less than 85 percent of expected).
- Intense fear of gaining weight or becoming fat, despite being significantly underweight.
- Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of current low body weight.
- The absence of at least three consecutive menstrual cycles (prior to menopause).
The diagnostic criteria for bulimia nervosa are summarized as follows:
- Recurrent episodes of binge eating during discrete periods of time (e.g., within any two-hour period), characterized by eating an amount of food that is definitely larger than most people would eat during a similar period of time, and a sense of lack of control over eating during the episode.
- Recurrent inappropriate compensatory behavior in order to prevent weight gain, such as self-induced vomiting; misuse of laxatives, diuretics, enemas, or other medications; fasting; or excessive exercise.
- Episodes of binge eating and inappropriate compensatory behaviors occurring, on average, at least twice a week for three months.
Screening questionnaires are available. For example, answers of "yes" to two or more of the questions below strongly suggest an eating disorder:
1. Do you make yourself sick because you feel uncomfortably full?
2. Do you worry you have lost control over how much you eat?
3. Have you recently lost more than 14 pounds in a three-month period?
4. Do you believe yourself to be fat when others say you are too thin?
5. Would you say that food dominates your life?
Lab testing may include blood tests, EKG, pregnancy testing, bone-density testing, or MRI of the brain.
- Psychiatric therapy is the treatment of choice. This may include cognitive-behavioral therapy, family-based therapy, and group therapy. Also, self-help manuals appear to be effective in reducing binge eating, and programs such as Overeaters Anonymous are often effective as well.
- Fluoxetine (Prozac) was recently approved for treatment of Bulimia by the Food and Drug Administration. It appears to be effective in about 60 percent of cases. Further, combining medication with psychiatric therapy appears to work better than either treatment alone.
- In severe cases, hospitalization and medical therapy may be necessary for refeeding and to treat electrolyte disturbances, dehydration, heart arrhythmias, and other complications.
- Vitamin and mineral supplementation may be necessary.
- A structured eating program may help restore healthy eating habits.
Eating Disorders: Nutritional Considerations
- Weight-Loss Treatments: Weight-loss treatments are effective for patients with binge eating disorder. Structured meal plans provided for weight loss may give binge eaters a feeling of greater control over eating.
- Vitamin and Mineral Deficiency: Vitamin and mineral deficiencies are common in individuals with eating disorders. More than half of patients with anorexia nervosa fail to meet the recommended dietary allowance (RDA) for vitamin D, calcium, folate, vitamin B12, zinc, magnesium, and copper. Deficiencies are also common for thiamine, niacin, other B vitamins, folate, vitamin C, vitamin E, and vitamin K.
Replacement of these and other nutrients is an important part of nutrition therapy. Zinc in particular has been found to improve recovery in people with anorexia by increasing weight gain and improving anxiety and depression. Calcium and vitamin D may improve osteoporosis.