Have States Reduced Obesity by Legislating More Physical Activity in Elementary School?

Did child obesity decline after 2016 food regulations in Chile?

We estimated trends in the prevalence of obesity and overweight among Chilean primary and secondary students before and after Chile's 2016 regulations on the marketing and availability of foods high in energy, total sugars, sodium, or saturated fat. We used data from Chile's Survey of Nutrition, which measured the body mass index (BMI) of students in government-funded schools. Using BMI thresholds defined by the World Health Organization, we calculated the prevalence of overweight and obesity for each year from 2013 to 2019 among students attending pre-kindergarten (age 4 years), kindergarten (age 5 years), first grade (6 years), and ninth grade (14 years). In ninth grade students, overweight and obesity prevalence rose by 2 percentage points over the 3 years after introduction of the 2016 regulations. In pre-kindergarten, kindergarten, and first grade, overweight and obesity fell 1 to 3 percentage points 1 year after the regulations were introduced, but rebounded to previous levels the next year. Chile's food regulations were not followed by a sustained decline in obesity in primary- and secondary-school students. Future research should examine whether and how children in Chile and other countries maintain high levels of overweight and obesity despite food regulations designed to reduce consumption of obesogenic foods and beverages.

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

Although the negative relationship between BMI and academic achievement (AA) is well documented, no prior studies have investigated the potential bi-directional relationship between BMI and AA in childhood. We investigated the longitudinal relationships between child BMI and AA across different school subjects (reading, math and science) and sexes. To do so, we employed the Early Childhood Longitudinal Study kindergarten cohort (2011), which is a nationally representative sample of American children who entered kindergarten in 2010-2011. We utilised 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 BMI and math/science achievement for girls (n 8540) (year-to-year effect sizes ranged from -0·01 to -0·04), but not for reading. In contrast, we did not find any evidence of reciprocal relationships between BMI and AA for boys (n 8940). Our results reveal that early weight status and academic performance may be jointly responsible for a vicious cycle of poor AA and unhealthy weight. Breaking the cycle from AA may complement existing obesity prevention strategies, particularly for girls in the science, technology, engineering and mathematics field.