Longitudinal effects of school policies on children's eating behaviors and weight status: findings from the childhood obesity study in China megacities.

OBJECTIVES

To examine longitudinal effects of school policies on children's weight status and eating behaviors, and study how these effects may vary by children's age, sex, and baseline weight status in China.

METHODS

Data were collected in 2015, 2016, and 2017 in an open cohort of 3298 children aged 6-17, their parents, and schools in five large cities across China (Beijing, Shanghai, Xi'an, Nanjing, and Chengdu). Children's weight, height, and waist circumference were measured, and their eating behaviors were self-reported. The 1691 children with such repeated measures in ≥ two waves were included in longitudinal data analysis with mixed effects models, testing the associations.

RESULTS

Having school vicinity food stall policy was associated with less frequent consumption of fast food (β = -0.14, p < 0.01) and snack (β = -0.84, p < 0.01). More significant associations were found between school policies and unhealthy eating behaviors for girls and children aged 6-11 than their counterparts. Among children without overweight or central obesity at baseline, having school cafeteria food policy was associated with lower risks for overweight and obesity (OR = 0.33, 95% CI: 0.17-0.63) and central obesity (OR = 0.47, 95% CI: 0.26-0.85). This existed for girls, but not for boys. School vicinity food stall policy was associated with lower BMI (β = -0.20, 95% CI: -0.37, -0.03) among all children and in girls (β = -0.28, 95% CI: -0.50, -0.05) without overweight at baseline.

CONCLUSIONS

School policies could reduce children's unhealthy eating behaviors and obesity risk in megacities in China. Children's age, sex, and baseline weight status modify the effects. School policies are important to fight the growing childhood obesity epidemic.