Greener Environments Linked to Healthier BMI in Children: JAMA

A new study published in the Journal of the American Medical Association observed children who moved to greener, less urbanized areas to show healthier BMI trajectories over time. Increased exposure to natural environments was associated with slower weight gain and a lower risk of developing overweight or obesity compared with peers who stayed in more urban settings

The birth cohorts from the Netherlands (PIAMA), Sweden (BAMSE), and the Czech Republic (ELSPAC-CZ) that took part in the EXPANSE (Exposome Powered Tools for Healthy Living in Urban Settings) project and had birth dates between 1991 and 1997 provided the harmonized data utilized in this longitudinal cohort analysis.

The participants were young people between the ages of 2 and 24 who had moved throughout their follow-up. Multiple exposures from the three exterior exposome domains were described using k Means clustering. After adjusting for pertinent variables, fixed-effects linear models were used to evaluate correlations between changes in the exposome and changes in the age- and sex-standardized body mass index (z-BMI).

The study comprised 4359, where 2215 (50.8%) were male. The average age at admission was 3.0 (1.1) years, and the average age at relocation was 7.7 (4.3) years. Different cohorts have different levels of parental education. Mean (SD) z-BMI was 0.2 (1.1), 0.4 (1.0), and 0.1 (1.2) at baseline and 0.0 (1.0), 0.3 (1.0), and 0.1 (1.1) after moving in PIAMA, BAMSE, and ELSPAC-CZ, respectively.

Moving to higher-hazard settings (more polluted, more gray space) was linked with increases in z-BMI for all domains in PIAMA; significant relationships were also reported for select domains and exposures in BAMSE and ELSPAC-CZ.

Moving to a more constructed environment was specifically linked to an increase in z-BMI that was consistent across cohorts: in BAMSE and PIAMA, an IQR increase in gray spaces was linked to increases in z-BMI of 0.04 (95% CI, 0.01-0.06) units and 0.05 (95% CI, 0.01-0.09) units, respectively.

In PIAMA, increases of 0.07 (95% CI, 0.02-0.12) and 0.07 (95% CI, 0.01-0.14) units in z-BMI for nitrogen dioxide (NO2) and fine particulate matter (PM2.5), respectively, were linked to an IQR increase in air pollution danger. Cohorts differed in the presence of impact modification by age at relocation and parental education. Overall, the results of this study indicate that children's and young adults' z-BMI trajectories were changed in response to abrupt changes in the built environment.

Source:

Saucy, A., Warkentin, S., Milà, C., Coloma, F., Yu, Z., de Bont, J., Bergström, A., Boer, J. M. A., Dadvand, P., de Hoogh, K., Gehring, U., Klánová, J., Mikeš, O., Melén, E., Nieuwenhuijsen, M., Shen, Y., Szabó, D., Vermeulen, R., Vlaanderen, J., … Tonne, C. (2025). Weight trajectories among youths following residential relocation. JAMA Network Open, 8(11), e2544164. https://doi.org/10.1001/jamanetworkopen.2025.44164