Longitudinal weight status, and academic achievement in elementary schoolchildren in the United States

Abstract

Background/Objectives. Childhood overweight and obesity have a well-established negative impact on children’s health. Overweight and obesity might also negatively impact children’s academic performance, but existing literature on this association is inconclusive. This study uses a longitudinal design in a large, diverse elementary school sample to rigorously test the association between longitudinal weight status and academic achievement. Analyses also investigate modification by sex, race/ethnicity, and cardiorespiratory fitness (CRF). Subjects/Methods. In a large suburban school district in the United States, 4 936 Grade 4 students were recruited. Demographic, course grade, and standardized test data were collected from school records for Grades 3 to 5, and body mass index (BMI) and CRF were assessed each year. Students wore accelerometers during the school day for up to 15 days across three semesters (Grade 4 Fall and Spring, Grade 5 Fall) to objectively measure physical activity. Multiple imputation addressed missing data and multilevel analyses controlled for student demographics and clustering within schools. Results. Unadjusted multilevel models found small negative associations for students who were persistently obese with course grades and standardized test scores, but these associations largely disappeared when controlling for demographic characteristics. Residual associations for math and writing course grades were attenuated when controlling for CRF, though some marginal negative associations for math and writing remained for students who became obese during follow up. There was no evidence of modification by sex or race/ethnicity. Conclusions Results suggest very small associations between obesity status and academic achievement that were largely explained by CRF. These findings support growing evidence that increasing CRF is more important than losing weight for improving children’s cognition and academic achievement.