Differences in the influence of the built environment and physical activity on obesity in urban and suburban contexts

In recent decades, the influence of the built environment and physical activity (PA) on obesity has attracted much research attention. However, findings often conflict partly because the studies are conducted in different cities or countries in which the context may vary not only in the built environments, but also in sociocultural and economic backgrounds. This study aims to contribute to the literature by examining urban and suburban areas of the same city, where the contextual differences are largely confined to the built environment. Using data from a two-day household survey conducted in Shanghai in 2018, we developed multi-group path analysis models to examine the connections between the built environment, PA, and obesity in urban and suburban settings. The findings reveal that urban residents engage in longer durations of PA across all types except semi-active transport PA, compared to suburban residents. Protective effects of PA on weight control differ by context: urban residents benefit more from active transport and leisure PA, while semi-active transport, leisure, and household PA reduce obesity risk for suburban residents. The mediating role of PA in the built environment-obesity relationship also varies. In urban areas, a greater land use mix and a higher density of parks promote leisure PA, indirectly reducing the risk of being obese. Conversely, in suburban settings, park density is positively associated with obesity, as it discourages leisure PA. Therefore, policies aimed at promoting a healthy lifestyle and weight management should be tailored specifically for people living in urban and suburban neighborhoods, respectively.