Puberty is hard enough on kids. It's worse for those don't conform to whatever beauty standards pre-teens are aggressively marketed these days. But a new study shows that for 11-year-old girls, obesity likely affects educational test scores throughout adolescence. For boys, the evidence remains unclear.
As part of an ongoing survey, researchers from a coalition of British universities measured how well some 4,000 children fared on the U.K.'s mandatory achievement tests (which include teacher assessments) at ages 11, 13, and 16. The girls who were obese at age 11 did significantly worse than their peers with healthy weights at all three ages. The same was true for girls who started off at a healthy weight at 11, but then became obese by 16.
The study, published in the International Journal of Obesity, was unique in that it tested for a wide range of confounding variables. Even while accounting for these factors—including, but not limited to, the age of the mother at delivery, ethnicity, socio-economic status, levels of physical activity, parents' educational attainment, and depression levels—the pattern for girls held.
So where does that leave us? And why are boys off the hook (as far as we know)? The authors suggest that there could be a teacher grading bias towards obese kids—one large study published in 2012 found that while obese students received lower grades from middle school through college, their measured intelligence and achievement test scores were no different from their peers. Other studies have shown that obese women face especially severe stigma because of their weight, a factor that could also contribute to obese kids' significant absenteeism from school.
The researchers also note that there is some evidence linking childhood obesity to decreased cognition. A recent study on mouse brains found that a neurotransmitter in obese mice appeared to sabotage their thinking and memory test scores. After giving the mice liposuction, the neurotransmitter disappeared, and subsequently, the mice did fine on the tests.
The cause of the education gap remains elusive, but could likely be a combination of factors. And while exercise might help with cognition, it won't eliminate the stigma of what it means to an obese teenage girl.