# Physical Activity Determinants Under the Double Burden of Malnutrition: Contrasting Pathways for Underweight and Overweight Chinese Adolescents

## TL;DR

This study explores how physical activity is influenced differently in underweight and overweight Chinese adolescents, highlighting the need for tailored public health strategies.

## Contribution

The study identifies distinct psychological and social pathways influencing physical activity among underweight and overweight Chinese adolescents.

## Key findings

- Normal-weight adolescents' physical activity is predicted by stage of change, friend support, self-efficacy, and perceived benefits.
- Overweight/obese adolescents rely more on friend support and social factors for physical activity.
- Underweight adolescents depend on internal factors like stage of change and self-efficacy for physical activity.

## Abstract

Background: Chinese adolescents face a dual burden of malnutrition, yet the weight-status-specific mechanisms underlying physical activity (PA) participation remain underexplored. Methods: We conducted a cross-sectional study among 1573 adolescents (aged 9–15 years) in Shangrao City, China. Validated scales measured social-ecological factors (family/peer support, physical environment), psychological factors (stage of change, self-efficacy, decisional balance), and PA participation. Data preprocessing utilized full information maximum likelihood to handle missing values. Confirmatory factor analysis was performed to validate the measurement model, followed by multi-group structural equation modeling to analyze pathway configurations across underweight (n = 187), normal-weight (n = 1070), and overweight/obese (n = 316) groups. Mediation effects were tested using bootstrapping with 5000 resamples. Results: Clear weight-specific patterns emerged. Normal-weight adolescents presented a fully functional comprehensive model where PA was predicted by the stage of change (β = 0.211, p < 0.001), friend support (β = 0.120, p < 0.001), self-efficacy (β = 0.092, p < 0.05), and perceived benefits (β = 0.095, p < 0.01). Underweight adolescents primarily relied on internal readiness driven by stage of change (β = 0.270, p < 0.001) and self-efficacy (β = 0.164, p < 0.05), with family support only indirectly influencing participation via psychological mediators. In contrast, overweight/obese adolescents showed a “socially dependent” pattern: friend support directly predicted PA levels (β = 0.136, p < 0.05), significantly enhanced self-efficacy (β = 0.370, p < 0.01), and effectively lowered perceived barriers (β = −0.165, p < 0.05). Additionally, the physical environment strongly impacted perceived benefits (β = 0.471, p < 0.01) but did not translate into action. Conclusions: These findings underscore the significant differences in PA determinants across the spectrum of malnutrition, necessitating targeted public health interventions to support the Healthy China 2030 initiative.