Does where you live influence your health? Yes, and maybe even more dramatically than you might expect.
When a U.S. Department of Housing and Urban Development (HUD) offered a program in the 1990s to move families out of poor neighborhoods, it created a unique opportunity not only to improve people’s day-to-day lives, but also to study how a change in environment might impact their health over the long term. Now, more than a decade later, the researchers have found that families who moved to lower-poverty neighborhoods had lower levels of obesity and diabetes than those who stayed behind. What’s more, the improvements in health were as significant as those that typically result from targeted diet and exercise interventions or the use of medications to treat diabetes.
“The results suggest that over the long term, investments in improving neighborhood environments might be an important complement to medical care when it comes to preventing obesity and diabetes,” says study author Jens Ludwig, a professor of public policy at University of Chicago
The HUD program, called Moving to Opportunity (MTO), wasn’t originally focused on tracking people’s health. It was designed to study the effect of the residential milieu on employment, income and education in families with children living in cities with a 40% or greater poverty rate. But Ludwig and his team were curious about how the rise in poverty in the U.S. has also mirrored the increase in obesity and diabetes and wondered, Could neighborhood and social factors influence health outcomes?
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The current study, published in the New England Journal of Medicine, is the first to conduct a social experiment that allowed the comparison of such outcomes in families — in this case, low-income single mothers and their children living in public housing — who were randomly assigned to live in different economic environments. Families who volunteered to join MTO entered a lottery, which randomly put them in one of three groups: those who received vouchers to move to a less disadvantaged neighborhood (with a poverty rate of less than 10%), those who got vouchers to live wherever they chose, and those who did not receive any vouchers or additional assistance.
Because of the randomized design of the program, scientists knew they could track and correlate changes in living circumstances to later health outcomes like obesity or diabetes. Most of the families — who were from Baltimore, Boston, Chicago, Los Angeles and New York — were followed for an average of 12 years, during which they answered survey questions about their neighborhood, jobs and health.
Among the 4,498 single moms who volunteered for the program, those who were assigned to move to lower-poverty areas were 19% less likely to have a BMI of 40 or higher, the cutoff for morbid obesity, and 22% less likely to have glucose levels typical of diabetes, compared with those who stayed in public housing. “Neighborhood disadvantages contribute to obesity and diabetes,” says Ludwig, while “improving the economic situations [of families] improves their health.”
But what is it about our neighborhoods exactly that affects health? Previous studies have shown that poverty-stricken neighborhoods tend to be food deserts — lacking good sources of nutritious food — that contribute to obesity and ill health in residents. Poor neighborhoods also often don’t have parks, sidewalks or other safe places for physical activity. Lack of access to medical care and inadequate education about the benefits of a healthy diet and exercise certainly play a role as well.
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And there’s something else that often gets overlooked: stress. Psychological stress due to financial hardship or chronic anxiety about physical safety can have adverse effects on people’s metabolism, leading to weight gain and conditions like heart disease and diabetes. The participants in the study undoubtedly had high stress — their motivation for enrolling in MTO centered around their desire to provide a safer environment for their families. Ludwig says half of the households reported at the start of the study that at least one family member had been the victim of a crime in the previous month.
Clearly, neighborhoods aren’t the direct or only cause of obesity or diabetes, but the study shows that they may play a previously unappreciated role in one of the biggest health challenges we face today. “We didn’t think of neighborhoods as having a health effect, but it turns out to have an effect in the ballpark of the size that we would see from medical interventions that address diabetes,” says Ludwig. That’s a huge boon for public policy makers, since it gives them another strategy for addressing the growing consequences of the obesity epidemic.
While previous studies have associated poverty and being part of a minority group to an increased risk of obesity and diabetes, the new findings offer stronger evidence to explain the connection. “This study raises the possibility that at least part of the elevated rates of obesity and diabetes among minorities compared to whites might be due to the fact that minorities tend to live in more disadvantaged neighborhoods,” Ludwig says.
And that suggests that when it comes to addressing the health problems of obesity and diabetes, simply improving medical care may not be enough. “People may need more than health care in order to be healthy,” he says.
Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.