Untangling the relationship between BMI and academic achievement in the elementary years

Abstract

Although the negative relationship between body mass index and academic achievement is well documented, no prior studies have investigated the potential bidirectional relationship between body mass index and academic achievement in childhood. We investigated the longitudinal relationships between child body mass index and academic achievement across different school subjects (reading, math, and science) and sexes. To do so, we employed the Early Childhood Longitudinal Study kindergarten cohort (ECLS-K: 2011), which is a nationally representative sample of American children who entered kindergarten in 2010-2011. We utilized the kindergarten–fifth grade longitudinal sample (n=17,480) and applied cross-lagged panel models with fixed effects to address unobserved heterogeneity. Our results showed significant but small reciprocal relationships between body mass index and math/science achievement for girls (n=8,540) (year-to-year effect sizes ranged from -.01 and -.04), but not for reading. In contrast, we did not find any evidence of reciprocal relationships between body mass index and academic achievement for boys (n=8,940). Our results reveal that early weight status and academic performance may be jointly responsible for a vicious cycle of poor academic achievement and unhealthy weight. Breaking the cycle from academic achievement may complement existing obesity prevention strategies, particularly for girls in the STEM field.