Risk Factors
Many factors contribute to the risk of developing an eating disorder.
Age
Dating disorders occur most often in adolescents and young adults. However, new research finds that they are increasingly prevalent among young children. Eating disorders are more difficult to identify in young children because they are rarely suspected.
Age of Onset for Bulimia. A 2004 study of high school students in the United States found that about 25% of girls and 10% of boys followed abnormal eating and weight control practices. Another study found that 2% of adolescent girls and 0.3% of adolescent boys fulfilled the criteria for bulimia. The average age of onset was 17.2 years. According to estimates, as many as 10% of college-aged women have bulimia. Some experts claim that even these percentages grossly underestimate the problem because many people with bulimia are able to conceal their purging and do not become noticeably underweight. For example, a European study detected bulimic behavior in 14.4% of adolescents 14 to 16 years old, with full-blown bulimia observed in 1.8% of girls and 0.3% of boys.
Age of Onset for Anorexia Nervosa. After asthma and obesity, anorexia nervosa is the third most common chronic illness in adolescent women. It is estimated to occur in 0.5% to 3% of all teenagers. Anorexia usually first occurs in adolescence with peaks at 13 to 14 years of age and at 17 to 18 years of age. Over the past 40 years, however, the incidence has been steady in teenagers, but it has increased threefold in young adult women.
Gender
Studies typically report that 90% of those with eating disorders are females. However, the prevalence in males appears to be increasing.For example, a 2003 Canadian health survey reported that 20% of the patients were male. A 2000 study of teenagers in Minnesota reported that 13% of girls and 7% of boys reported disordered eating behavior.
When eating disorders occur in young adults, men are more apt to conceal them, so the incidence among males may be underreported. One study of Navy men, for example, reported a prevalence of 2.5% for anorexia, 6.8% of bulimia, and 40% for binge eating.
Studies suggest that the psychiatric and behavioral profiles of men and women with eating disorders are very similar to each other, although there are some differences. Excessive physical activity is more prevalent in males with anorexia. Anorexics tend to have very low sexual interest, although there is a higher rate of homosexuality among young men than women. Sexual preference for men may tend to differ, however, by the specific eating disorders. One study reported that 42% of male civilians with bulimia were homosexual or bisexual while 58% of the men with anorexia were asexual.