One in five US school-aged children is obese. The National School Lunch program is crucial for children's intake, accounting for about 1/3 of total daily calories. Previous research on obesity and school-lunch consumption has not included middle school, an important time to establish lifestyle habits that persist into adulthood.
To explore the relationship between school-lunch participation and consumption with child body mass index (BMI) and BMI category.
Study Design, Setting, Participants
This is a secondary analysis of data collected from middle-school students in Birmingham, AL.
Child weight and height were measured and BMI calculated and categorized as 2 groups (underweight + healthy weight [<85th percentile], overweight + obese [≥85th percentile]). At pre- and post-lunch, researchers weighed and photographed school-lunch trays for 5 consecutive weekdays to capture amounts at pre and post. “Offer-versus-serve” was available so students could refuse some meal components. Mixed-effects regression explored BMI and logistic regression explored BMI category (dependent variables) with school lunch participation, pre-, post-amounts, and average consumption of school lunch as independent variables, age, gender, race/ethnicity, family income as fixed effects, and school site as a random effect.
The sample included 288 students (mean age 12 years; 46% male; 36% White, 47% African American, 9% Hispanic/Latino, 8% Other/missing) from 15 schools, 6 school districts. There was no significant relationship between school-lunch participation and BMI/BMI category. However, pre-, post-amounts, and average consumption of school-lunch in grams were all significant (β=2.23, β=-2.29, and β=1.82 respectively, P <0.001) with BMI. The odds of being overweight/obese will increase by 48.3% with every 1 unit increase of the standardized average lunch consumption.
School-lunch consumption was positively related with BMI and BMI category among middle school children. As BMI and obesity risk increased, pre-amounts and average consumption were larger and post-amounts were smaller. Future analyses will assess the association of school-lunch food groups and energy intake with BMI.
Institute of Education Sciences, United States Department of Education