Obese kids as bright as thinner peers

Previous studies have shown that children who are heavier are less likely to do well at school. However, Dr Stephanie von Hinke Kessler Scholder from University of York argues it's vital to understand what drives this association. "We sought to test whether obesity 'directly' hinders performance due to bullying or health problems, or whether kids who are obese do less well because of other factors that are associated with both obesity and lower exam results, such as coming from a disadvantaged family," Dr Scholder explains.

Researchers examined data on almost 4,000 members of the Children of the 90s Birth Cohort Study. These data include the children's DNA. It is well known that genes are randomly allocated within a population, irrespective of factors such as socio-economic position. The researchers combined the latest developments from genetic epidemiology with statistical methodologies in economic and econometric research. Using two carefully chosen 'genetic markers', the research team was able to identify children with a slightly higher genetic pre-disposition to obesity.

"Based on a simple correlation between children's obesity as measured by their fat mass and their exam results, we found that heavier children did do slightly worse in school," Dr Scholder points out. "But, when we used children's genetic markers to account for potentially other factors, we found no evidence that obesity causally affects exam results. So, we conclude that obesity is not a major factor affecting children's educational outcomes."

These findings suggest that the previously found negative relationship between weight and educational performance is driven by factors that affect both weight and educational attainment. Future research should focus on other determinants of poor educational outcomes, such as social class or a family's socio-economic circumstances, Dr Scholder points out.

The finding that obesity is not a cause of poorer educational performance is, the researchers suggest, a positive thing. "Clearly there are reasons why there are differences in educational outcomes, but our research shows that obesity is not one of them," Dr Scholder argues.