Walking mediates associations between neighborhood activity supportiveness and BMI in the Women's Health Initiative San Diego cohort

Objectives: To investigate whether walking mediates neighborhood built environment associations with weight status in middle- and older-aged women. Methods: Participants ( N=5085; mean age=64±7.7; 75.4% White non-Hispanic) were from the Women's Health Initiative San Diego cohort baseline visits. Body mass index (BMI) and waist circumference were measured objectively. Walking was assessed via survey. The geographic information system (GIS)-based home neighborhood activity supportiveness index included residential density, street connectivity, land use mix, and number of parks. Results: BMI was 0.22 units higher and the odds ratio for being obese (vs. normal or overweight) was 8% higher for every standard deviation decrease in neighborhood activity supportiveness. Walking partially mediated these associations (22-23% attenuation). Findings were less robust for waist circumference. Conclusions: Findings suggest women who lived in activity-supportive neighborhoods had a lower BMI than their counterparts, in part because they walked more. Improving neighborhood activity supportiveness has population-level implications for improving weight status and health.