Previous cross-sectional "snapshot" studies have shown that healthier, less-obese people are more likely to live in neighborhoods with supermarkets and access to fresh food, and to some extent in neighborhoods that are walkable.
"Interpretation of results from cross-sectional analyses is limited since that type of study can't determine whether weight gain preceded the neighborhood exposure," said researcher Dr. Amy Auchincloss, an assistant professor in the Drexel University School of Public Health.
Auchincloss and her co-authors consider their new study's results more robust than much of the other work to date on neighborhood risk factors and obesity. They selected participants not obese and baseline and tracked who became obese during a five-year follow-up period and they accounted for person-level factors that could influence both health status and neighborhood choice.
Auchincloss led the new study with co-authors from University of Michigan School of Public Health, University of California Berkeley, Johns Hopkins School of Medicine and Gramercy Research Group.
The researchers analyzed health data from 4,008 adults from six cities across the United States, followed over a period of five years as part of a larger Multi-Ethnic Study of Atherosclerosis. The study participants completed surveys about qualities of the area surrounding their homes: To what extent are healthy foods available nearby? And how walkable do they perceive the neighborhood to be?
During the five-year study period, 406 of the participants became obese.
A healthy food environment was associated with lower obesity - even after accounting for factors such as age, sex, income and wealth, education, ethnicity, smoking, diet, physical activity, as well as walkability of the neighborhood.
Walkability was also associated with lower obesity, but this association was not independent of healthy food environment
"Healthy food environments and walkability are often correlated in urban areas which is why it can be hard to assess their independent effects," Auchincloss noted.
Auchincloss and her co-authors suggested that altering residential environments so that healthy lifestyles are easy to maintain, may be a pre-condition for promoting healthy behavior - but that these changes should work in combination with other strategies for improving health.
The study was recently published in the journal Obesity.