Dietary Patterns and Physical Activity in Relation to Physical Fitness among Urban Adolescents in Indonesia: The Mediating Role of Body Composition

Abstract

Physical fitness is a critical marker of adolescent health. Although physical activity and dietary patterns are widely recognized as behavioural correlates of fitness, evidence on their integrated pathways particularly through body composition remains limited among urban adolescents in developing countries. This cross-sectional explanatory study examined the direct and indirect associations of physical activity and dietary patterns with physical fitness, with body composition tested as a mediating variable, among urban adolescents aged 13–15 years in Jakarta, Indonesia (N = 300). Physical activity was measured using the Global Physical Activity Questionnaire (GPAQ) and expressed as total MET-minutes/week. Dietary patterns were assessed using an eight-item dietary behaviour questionnaire (five-point Likert scale), of which three indicators (protein-source intake, water intake, and reverse-scored fried-food consumption) were retained in the final formative construct. Body composition was measured using bioelectrical impedance analysis (Xiaomi Mi Body Scale 2). Physical fitness was assessed using the V Sit-and-Reach, Sit-Up, Squat Thrust, and Kasch Pulse Recovery Step tests. Data were analysed using Structural Equation Modelling–Partial Least Squares (SEM-PLS 4; Ringle et al., 2024). Dietary patterns showed the strongest direct association with physical fitness (β = 0.482, p < .001), larger than that observed for physical activity (β = 0.105, p = .040). Body composition was significantly associated with physical fitness (β = 0.251, p < .001) and carried significant indirect associations of both dietary patterns (β = 0.107, p < .001) and physical activity (β = 0.081, p < .001) with physical fitness. The model explained 53.6% of the variance in physical fitness (R² = 0.536, adjusted R² = 0.531) and 43.6% of the variance in body composition (R² = 0.436, adjusted R² = 0.432). Given the cross-sectional design, these findings should be interpreted as associations rather than confirmed causal or mediating effects. The results suggest that the retained dietary behaviours (protein-source and water intake and lower fried-food consumption) and body composition reflected here by lean mass and hydration status rather than adiposity are important correlates of adolescent fitness and support further longitudinal or experimental investigation of interventions that integrate nutrition improvement with physical activity promotion.