Strong associations between built environment and BMI

New York City dwellers who reside in densely populated, pedestrian-friendly areas have significantly lower body mass index levels compared to other New Yorkers, according to a new study by the Mailman School of Public Health.

Placing shops, restaurants and public transit near residences may promote walking and independence from private automobiles.

"There are relatively strong associations between built environment and BMI, even in population-dense New York City," said Andrew Rundle, DrPH assistant professor of Epidemiology at the Mailman School and lead author.

The researchers looked at data from 13,102 adults from New York City's five boroughs. Matching information on education, income, height, weight and home address with census data and geographic records, they determined respondents' access to public transit, proximity to commercial goods and services and BMI, a measure of weight in relation to height.

The authors discovered that three characteristics of the city environment - living in areas with mixed residential and commercial uses, living near bus and subway stops and living in population-dense areas - were inversely associated with BMI levels. For example, city dwellers living in areas evenly balanced between residences and commercial use had significantly lower BMIs compared to New Yorkers who lived in mostly residential or commercial areas.

"A mixture of commercial and residential land uses puts commercial facilities that you need for everyday living within walking distance," Dr. Rundle said. "You're not going to get off the couch to walk to the corner store if there's no corner store to walk to."

Although previous studies have addressed the relationship between obesity and the urban built environment in smaller, newer cities, this study is the first to evaluate the relationship in older, larger New York.