Does obesity affect school performance?

(Health.com) -- Obese children and teenagers face a slew of potential health problems as they get older, including an increased risk of diabetes, heart attacks, and certain cancers. As if that weren't enough, obesity may harm young people's long-term college and career prospects, too.

In recent years, an uneven yet growing body of research has suggested that obesity is associated with poorer academic performance beginning as early as kindergarten. Studies have variously found that obese students -- and especially girls -- tend to have lower test scores than their slimmer peers, are more likely to be held back a grade, and are less likely to go on to college.

The latest such study, published this week in the journal Child Development, followed 6,250 children from kindergarten through fifth grade and found that those who were obese throughout that period scored lower on math tests than non-obese children.

What's more, this pattern held even after the researchers took into account extenuating factors that can influence both body size and test scores, such as family income, race, the mother's education level and job status, and both parents' expectations for the child's performance in school.

"In boys and girls alike who entered kindergarten with weight problems, we saw these differences in math performances emerge at first grade, and the poor performance persisted through fifth grade," says lead researcher Sara Gable, Ph.D., an associate professor of nutrition and exercise physiology at the University of Missouri-Columbia.

The study had some limitations, however, and the results revealed some potentially important inconsistencies with respect to gender and age. For instance, the link between obesity and test scores was weaker -- or nonexistent, in the case of boys -- if the children became obese in the third or fifth grade, as opposed to kindergarten.

Overall, though, the findings jibe with evidence stretching back more than a decade. "I think it's been established that there's a link between students' obesity or physical fitness and academic achievement," says Rebecca London, Ph.D., a senior researcher at Stanford University's John W. Gardner Center for Youth and Their Communities, in Stanford, Calif.

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