Association of greenness with overweight and obesity in Bangladesh: cross-sectional geospatial analysis of 42,081 participants

Background: Features of neighbourhoods, including green space, have been shown to shape obesity and health in adults. However, research is predominantly from Europe and North America.

Purpose: We explored the cross-sectional association of geospatially-derived indicators of neighbourhood greenness, tree cover and built-up areas with overweight and obesity in Bangladesh. We tested whether associations varied by urbanicity and household income.

Methods: We used data from 42,081 Bangladeshi adults enrolled in South Asia Biobank between 2017-2022. Using a geographical information system, we constructed a 500m buffer around home address. We quantified greenness using the normalized difference vegetation index. We quantified tree cover and built-up areas using the WorldCover dataset. Adjusted regression models explored the association of (a) greenness; (b) tree cover and (c) built up areas with overweight and obesity defined using (i) body mass index; (ii) waist circumference and (iii) waist-hip ratio. We tested for interactions by urbanicity and household income.

Results: 49% of participants were overweight or obese. Higher greenness was associated with lower odds of overweight and obesity across body mass index (OR=0.90, 95%CI 0.86 to 0.93), waist circumference (OR=0.87, 95%CI 0.84 to 0.90) and waist-hip ratio (OR=0.87, 95%CI 0.84 to 0.91). Conversely, higher amounts of built-up areas were associated with higher odds of overweight and obesity across body mass index (OR=1.10, 95%CI 1.08 to 1.11), waist circumference (OR=1.08, 95%CI 1.07 to 1.10) and waist-hip ratio (OR=0.87, 95%CI 0.84 to 0.91). Associations were strongest in urban participants. Tree cover associations were not statistically significant.

Conclusions: In Bangladeshi adults, higher greenness and lower amounts of built-up areas were associated with more favourable body composition, particularly in urban dwellers.

Practical implications: This study aligns with others indicating beneficial associations of green space with health, and with policy to support greening of cities.

Funding: National Institute for Health Research (16/136/68, 133205).