Associations between parental role modeling of physical activity and overweight and obesity in children and adolescents: words, actions, or both? A cross-sectional study of young children’s population in Shanghai

BACKGROUND: Child and adolescent overweight and obesity are rising in China, yet how parental words, namely verbal encouragement, and actions, namely parents' own physical activity, relate to weight status remains unclear. This study estimated the associations of four observed parental role-modelling patterns, defined by parental verbal support and guideline-level parental physical activity, with overweight and obesity in children and adolescents. METHODS: Cross-sectional data were drawn from the Shanghai site of the Physical Activity and Fitness in China, The Youth Study from 2016 to 2020. The study included children and adolescents in Grades 4 to 12, each linked to one responding parent. Parental verbal support and parental physical activity were assessed by questionnaire. Two binary indicators, verbal support and guideline-level parental physical activity, were cross-classified to define four role-modelling patterns: no verbal support and no guideline-level parental physical activity (NS), verbal support only (VO), guideline-level parental physical activity only (AO), and both verbal support and guideline-level parental physical activity (BS). Child height and weight were measured objectively, BMI was calculated, and overweight or obesity was defined using WHO age- and sex-specific references. We used cluster-adjusted logistic regression to estimate adjusted odds ratios (aORs) for overweight or obesity, with adjustment for sociodemographic covariates. Subgroup-specific estimates were examined descriptively, and formal interaction tests were conducted in the full analytic sample. RESULTS: Data from 18 479 parent-child dyads (aged 9-18 years) were analysed; VO was most common (42.1%), followed by BS (26.8%), NS (22.4%), and AO (8.7%). Overall, 23.2% had overweight or obesity. Compared with NS, AO was associated with lower odds of overweight or obesity (aOR 0.82, 95% CI 0.69-0.96). BS was associated with even lower odds (aOR 0.57, 95% CI 0.50-0.65), suggesting a greater magnitude of association, whereas VO showed no evidence of association (aOR 0.99, 95% CI 0.98-1.01). BS was associated with lower odds across all examined subgroups, whereas the association for AO was more evident in Grades 7-9, non-only children, and higher-income households. CONCLUSION: Guideline-level parental physical activity was more consistently associated with healthier weight status among children and adolescents than verbal support alone. The combination of verbal support and guideline-level parental physical activity was associated with the lowest odds of overweight or obesity. Family-based obesity prevention should support parents in developing active routines and aligning verbal encouragement with their own physical activity.