Study: Better neighborhood lowers obesity, diabetes risk

From the article: 

Low-income moms who move from very poor neighborhoods to less disadvantaged ones lower their risk of becoming extremely obese and developing type 2 diabetes, a study reveals.

"This research shows how important the environment can be for people's health," says the study's lead author, Jens Ludwig, a professor of social service administration, law and public policy at the University of Chicago.

Obesity increases people's risk of developing type 2 diabetes, heart disease and other serious health problems. People in poorer neighborhoods are at a higher risk of becoming too heavy because they may not have access to grocery stores that are well-stocked with healthy fare such as fresh fruits and vegetables, often don't have safe places to be physically active and may have greater concerns about safety, which could impact their psychological stress and eating habits, Ludwig says.

The study is the first to use data from a randomized experiment to learn about the connection between neighborhoods and risk of obesity and diabetes, he says.

Ludwig and colleagues studied about 4,500 women with children who lived in public housing in high-poverty areas (40% or more of the residents had incomes below the federal poverty level) in Baltimore, Boston, Chicago, Los Angeles and New York City. The majority were either black or Hispanic.

The poverty level for a single mother with two children is currently about $17,500 a year.

The participants were all part of a long-term housing study by the Department of Housing and Urban Development (HUD). From 1994 to 1998, the families who volunteered to participate were randomly assigned to different groups. One group received rent-subsidy vouchers so they could move to a higher-income neighborhood — where about 10% of the residents were below the poverty level. Other women were assigned to the control group and didn't get the rent subsidy.

From 2008 to 2010, researchers did follow-up health assessments including blood testing for diabetes. Among the findings, which appear in today's New England Journal of Medicine:

•14.4% of women who were offered the opportunity to move to better neighborhoods were extremely obese (a body mass index, or BMI, of 40 or greater) at follow-up vs. 17.7% of women in the control group.

•16.3% of women who had the chance to move had diabetes vs. 20% of women in the control group.
Overall, about 7% of U.S. women are extremely obese. About 14% of black women are in that category. A 5-foot-4 woman who is extremely obese weighs 235 pounds or more, Ludwig says.

Having diabetes increases medical spending by $5,000 annually per person, he says, so this research suggests "that investing in neighborhood environments could substantially reduce health care spending over the long term."

Ludwig says the difference between the cost of public housing and the rent-subsidy vouchers for private housing is negligible, but both are expensive. The number of people living in high-poverty neighborhoods is going up, he says. "This may explain part of the increase in obesity and diabetes," Ludwig says.

Robert Whitaker, a public health and pediatrics professor at Temple University in Philadelphia and a researcher on this study, says, "People's health habits are often constrained by the choices they face in their neighborhoods.

"This study is one of the strongest pieces of evidence yet that improving the environments where low-income families live can have a meaningful impact on their risk of chronic disease."

William Dietz, director of the Centers for Disease Control and Prevention's Division of Nutrition, Physical Activity and Obesity, says that this report emphasizes "that place matters. What's striking is that there is a significant impact on severe obesity."
Stephanie Broyles, an assistant professor and researcher at the Pennington Biomedical Research Center in Baton Rouge, says these latest findings show "we can't just ask individuals to change their behaviors; we have to change the environment as well."

Neighborhoods, Obesity, and Diabetes — A Randomized Social Experiment
Jens Ludwig, Ph.D., Lisa Sanbonmatsu, Ph.D., Lisa Gennetian, Ph.D., Emma Adam, Ph.D., Greg J. Duncan, Ph.D., Lawrence F. Katz, Ph.D., Ronald C. Kessler, Ph.D., Jeffrey R. Kling, Ph.D., Stacy Tessler Lindau, M.D., Robert C. Whitaker, M.D., M.P.H., and Thomas W. McDade, Ph.D.
N Engl J Med 2011; 365:1509-1519 October 20, 2011

BACKGROUND
The question of whether neighborhood environment contributes directly to the development of obesity and diabetes remains unresolved. The study reported on here uses data from a social experiment to assess the association of randomly assigned variation in neighborhood conditions with obesity and diabetes.

METHODS
From 1994 through 1998, the Department of Housing and Urban Development (HUD) randomly assigned 4498 women with children living in public housing in high-poverty urban census tracts (in which ≥40% of residents had incomes below the federal poverty threshold) to one of three groups: 1788 were assigned to receive housing vouchers, which were redeemable only if they moved to a low-poverty census tract (where <10% of residents were poor), and counseling on moving; 1312 were assigned to receive unrestricted, traditional vouchers, with no special counseling on moving; and 1398 were assigned to a control group that was offered neither of these opportunities. From 2008 through 2010, as part of a long-term follow-up survey, we measured data indicating health outcomes, including height, weight, and level of glycated hemoglobin (HbA1c).

RESULTS
As part of our long-term survey, we obtained data on body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) for 84.2% of participants and data on glycated hemoglobin level for 71.3% of participants. Response rates were similar across randomized groups. The prevalences of a BMI of 35 or more, a BMI of 40 or more, and a glycated hemoglobin level of 6.5% or more were lower in the group receiving the low-poverty vouchers than in the control group, with an absolute difference of 4.61 percentage points (95% confidence interval [CI], −8.54 to −0.69), 3.38 percentage points (95% CI, −6.39 to −0.36), and 4.31 percentage points (95% CI, −7.82 to −0.80), respectively. The differences between the group receiving traditional vouchers and the control group were not significant.

CONCLUSIONS
The opportunity to move from a neighborhood with a high level of poverty to one with a lower level of poverty was associated with modest but potentially important reductions in the prevalence of extreme obesity and diabetes. The mechanisms underlying these associations remain unclear but warrant further investigation, given their potential to guide the design of community-level interventions intended to improve health. (Funded by HUD and others.)