What puts teenage girls at risk of obesity? Maybe not what you think!

Eating lots of high-fat foods, going on binges, and not being physically active do not predict obesity in teenage girls, according to a prospective study in nearly 500 girls between 11 and 15 years old. Rather, frequent dieting, radical weight-control behaviors such as vomiting and laxative use, and symptoms of depression are strong predictors. So is parental obesity-a finding that was not surprising.

Participants in the five-year investigation, drawn from eight private and public schools in a metropolitan area of the Southwest, completed a survey, primarily about behaviors. Investigators adapted standard special-purpose questionnaires to assess how often the responding teenager ate common high-fat foods, engaged in binge eating, and participated in a range of activities; whether she dieted to lose weight or practiced compensatory behaviors, such as vomiting or laxative or diuretic abuse; whether she had depressive symptoms; and whether she perceived either or both of her parents as overweight. The teenagers also participated in a structured interview and had their weight and height measured and body mass index (BMI) calculated.

Investigators then measured height, weight, and BMI annually for the next four years and calculated what psychological and behavioral risk factors predicted onset of obesity. Girls who repeatedly used compensatory behaviors were most likely to become obese during the course of the study. Perception of parental obesity and frequent dieting were also strong risk factors. Each reported symptom of depression increased the risk of obesity fourfold. Eating a high-fat diet was the weakest predictor of obesity (Stice E et al: J Consult Clin Psychol 2005;73:195).