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, reports Health.com.
In recent years, 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.
Moreover, this pattern held even after the researchers took into account 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.
Overall, the findings fit 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 Gardner Center for Youth and Their Communities, in Stanford, California.
But London and other childhood obesity experts caution that this emerging link is much more complicated than it seems. No one knows for certain why obesity and school performance are related, or whether one directly causes the other.
As London puts it, “Is it the actual state of obesity – those extra pounds – that are somehow influencing students’ achievement, or is it something related to the obesity but not the actual pounds?”
“Social skills and emotional well-being seem to be in the middle of the relationship,” says Becky Hashim, Ph.D., a clinical child psychologist with the Children’s Hospital at Montefiore, in New York City, who was not involved in the study.
However, it’s not clear whether obesity causes emotional problems or vice versa. On the one hand, Hashim says, being obese could weaken social skills if a child becomes isolated due to bullying or stigmatization. On the other hand, she adds, poor social skills could lead to sadness, which could lead to poor eating habits and weight gain if a child turns to food for comfort.
“Feelings of sadness or loneliness or anxiety in and of themselves may get in the way of school performance,” Hashim says. “It may be more difficult to pay attention. These kids may be less likely to ask a question.”
It’s also possible that some of the well-documented health problems associated with childhood obesity – such as asthma, diabetes, and sleep disorders – may interfere with schoolwork or cause kids to miss class time, Gable says.
For example, she says, an obese child “who also has sleep apnea may not be getting adequate-quality sleep at night, which could be interfering with the learning process.”
Even more insidiously, excess weight or physical inactivity might sap a child’s brainpower at the cellular level, by causing inflammation and other harmful biological processes, says Robert Siegel, M.D., director of the Center for Better Health and Nutrition, a pediatric obesity clinic at Cincinnati Children’s Hospital.
“Obesity affects virtually every organ system in the body, including the brain,” Siegel says. “It’s an inflammatory state, and that may have effects on the developing mind.”