The Associations between the Home and School Environments and Child Body Mass Index: A Growth Curve Modeling Approach

Background and Purpose – Child obesity is one of the most prominent health concerns of the modern era; the most recent nationally representative data find that 31.9% of American children aged 2-19 years old were overweight or obese (body mass index >=85th percentile), a substantial increase over comparable figures from the past few decades. However, despite a voluminous body of literature dedicated to exploring the causes of child obesity, the full set of environmental conditions responsible for this epidemic are still unknown. Moreover, many previous studies have focused on only one or a few potential causes, limiting our understanding of the etiology of a health condition that is likely multi-faceted. To partly address these gaps in previous literature, this study uses an ecological approach to simultaneously examine the role of the home and school environments in the growth of body mass index (BMI) over the period of kindergarten to 5th grade.

Methods – This study used data from Early Childhood Longitudinal Study – Kindergarten Cohort (ECLS-K), a nationally representative survey of kindergarten children initiated in 1998. The final sample consisted of approximately 9,600 children who had the requisite amount of data available. Making use of the ECLS-K survey design, which collected longitudinal data on schools, teachers, children, parents, and homes, I used growth curve modeling to assess whether a number of variables related to the school and home environments were associated with changes in BMI over the period of study as well as changes in the rate of growth of BMI. In order to assess the possible impact on children's overweight or obese status, I also conducted simulation analyses, which systematically varied those factors found to be significant in growth curve models.

Results – A number of different aspects of the home and school environments were found to be significantly associated with BMI. These included the hours of sleep children got per night, the number of breakfasts they ate at home, the average minutes of television they watched daily, the average hours their mothers worked per week, the number of school lunches they ate, the minutes of recess they had per week, and whether or not their schools had adequate gyms and cafeterias. These results were robust to the inclusion of a vast number of controls, including children's level of activity. Simulation results suggested that when considered jointly, the home and school environments could substantially affect the chances of a child becoming overweight or obese.

Conclusions and Implications – This study found that a number of home and school factors were significantly associated with children's BMI. These findings provide important direction for future research and potential policy interventions aimed at reducing the proportion of children who are overweight or obese. For one, they suggest the importance and feasibility of considering the role of multiple environmental influences on child obesity within one analytic framework. In addition, they indicate a variety of home and school characteristics, which, after further study could prove to be useful targets for anti-obesity policy and programming.