By Robbie Webber
Research in the last ten years has linked walkability, improved pedestrian environments, mixed-use development, and even older housing stock—a proxy for neighborhoods built for walking as opposed to driving—with improved public health measures related to weight. A new longitudinal study from McGill University is the first to study changes in body mass index over a relatively long time period as a function of walkability.
The study tracked body mass index for 12 years among 2943 young and middle-aged adults (18-55 years old) across Canada who lived in urban areas (≥ 50,000 population), including both those who changed residential location once within the study period and those who did not move. Neighborhoods were divided into walkable quartiles using Walk Score, with the most walkable neighborhoods scoring between 70-100 points, and the least walkable 0-39 points.
They found that moving to a more or less walkable environment can affect the BMI of men. They found no detectable influence for women. On average, men living in highly walkable neighborhoods had lower BMIs; but moving to a new neighborhood also had an effect on BMI. During the study period, the average BMI among the men increased, but the trajectories of the weight gain were different depending on the walkability of the area. Men who moved from the least walkable to most walkable neighborhoods lowered their weight, and thus their BMI, by an average of 1 kg/m2, and those who moved from a highly walkable neighborhood to a least-walkable neighborhood gained an average of .45 kg/m2.
The study is interesting in not only controlling for socio-economic factors such as education, income, marital, and immigration status, but also individual behaviors such as leisure time physical activity, utilitarian walking, and smoking. Even controlling for utilitarian walking, the BMI for men living in very walkable neighborhoods still was lower than those in low-walkability settings. The researchers conclude, “This suggests that there could be other factors such as neighborhood social norms that might influence body weight and are worth further exploration.”
Robbie Webber is a Senior Associate at SSTI.
By Robbie Webber