The Mediating Effect of Concurrent Changes in Dietary Behaviors on the Associations Between Intervention and Changes in Adiposity Outcomes: Evidence from a Cluster-Randomized Controlled Trial

Behavioral interventions have been shown to be effective in improving dietary behavior and reducing childhood obesity. There is limited evidence on how concurrent changes in dietary behavior from intervention studies affect childhood obesity. The present study aimed to evaluate the mediating effect of concurrent changes in dietary behaviors between the intervention and changes in adiposity indicators. This study included 1180 children from the DECIDE-Children study, which was conducted across three areas in China, aiming to promote children's healthy diet and physical activity, while also engaging schools and families to support children's behavioral changes. Dietary behaviors were collected by a revised version of the Food Frequency Questionnaire and a self-designed questionnaire. Adiposity outcomes were objectively measured by trained personnel. Generalized linear mixed models were used to estimate the association between scores of dietary behavioral changes and adiposity indicator changes. Mediation analyses were used to evaluate how scores of dietary behavioral changes mediated the effect of intervention on adiposity indicator changes. Six hundred children in the intervention group and five hundred and eight in the control group with both baseline and follow-up data were included. Each increase in dietary behavioral change score was associated with a 0.06 (p = 0.016) decrease in changes in BMI and other adiposity indicators. Scores of dietary behavioral changes mediated 13.87% (p < 0.001), 11.81% (p < 0.001), 17.60% (p = 0.024), and 16.78% (p = 0.032) of the association between intervention and changes in body mass index (BMI), BMI z-score, body fat percentage, and waist circumference, respectively. Scores of dietary behavioral changes mediated the intervention effect on adiposity indicator changes. Future interventions targeting childhood obesity should incorporate promoting multiple dietary behaviors simultaneously.