Although risk factors for binging and purging tend to differ between adolescent boys and girls, dieting and being teased or criticized about their weight may trigger such behavior in either sex, investigators found.

“It is, therefore, of utmost importance that parents, teachers, and clinicians promote maintaining a healthy weight without overemphasizing the importance of weight or stigmatizing overweight youth,” Dr. Alison E. Field and colleagues emphasize in a report on the research.

Field and her group investigated risk factors that might lead to binging and/or purging by analyzing data on 6,919 girls and 5,618 boys, aged 9 to 15 years at the outset, who were participating in the GUTS study, an acronym for Growing Up Today Study.

During the 7 years the teens were followed, 4.3 percent of the females and 2.1 percent of the males started to binge eat. The incidence was higher among subjects who were at least 14 years old.

Purging (vomiting or using laxatives) was more common among females: 5.3 percent vs 0.8 percent. Among females but not males, the incidence increased with age.

Among girls and boys, dieting and high levels of concern about weight were independent risk factor for both behaviors.

“We found that dieters were more likely to be overweight, so it could seem that overweight youth were at higher risk,” Field commented. However, multivariate analysis showed that dieting predicted binging or purging, regardless of weight. “In other words, being overweight only increases your risk if you are concerned about your weight and trying to control your weight. Overweight youth who aren’t dieting were actually at lower risk.”

“These results suggest that we need to move young people away from a quick-fix dieting mentality towards more realistic weight goals and less extreme weight control methods,” she added.

Only among young girls was a maternal history of an eating disorder a risk factor for purging behavior (adjusted odds ratio 2.9).

Among females, being teased by males about weight increased the risk of purging, while males were more susceptible to binge eating when their fathers made negative comments about their weight.

Bulimia - binging and purging - was rare. However, females who reported that it was important to their peers that they be thin were 4 times more likely to become bulimic.

SOURCE: Archives of Pediatrics and Adolescent Medicine, June 2008.