Abstract
Mainstream public health theories of obesity attribute current, unprecedented numbers of obese youth to changes in eating practices and levels of physical activity, in turn leading to greater energy consumption and lesser energy expenditure. While substantial research has examined energy consumption among school-age children, key modes of energy expenditure such as active school transport (AST) remain underexplored. Using AST data obtained from the California Safe Routes to Schools program and child health data from the California Physical Fitness Test, we examined the association between AST and child obesity among school-age children and disambiguated this relationship introducing the variable poverty. We found that greater AST correlated with higher rates of child obesity and higher rates of child poverty, which in turn correlated with worse child health and obesity rates. Our findings suggest that child poverty explains the positive relationship between AST and child obesity that has puzzled investigators. Our analysis also reveals recurring blind spots in the public health literature, which often acknowledges that poverty begets poor health yet calls for environmental changes while rarely calling for eliminating poverty, one critical social determinant of health, even as these determinants have become legitimate objects of scientific inquiry. We propose that while environmental changes may improve the health of the poor, the only effective way to improve child health and reduce child obesity is to eliminate or dramatically reduce child poverty, a sociopolitical issue. This study is part of a larger project evaluating socio-political determinants of child health.
Acknowledgements
The authors wish to acknowledge Mr Paul Tang at the University of California San Francisco for his invaluable assistance with data analysis and Austin Brown at the National Center for Safe Routes to Schools Highway Safety Research Center at the University of North Carolina and Lisa Cirill and Victoria Custodio at the California Department of Public Health for their generous assistance with data collection, also partly supported by a California Department of Transportation (Caltrans) grant.