More walkable neighborhoods may reduce obesity, diabetes
People living in walkable neighborhoods are more likely to engage in physical activity and less likely to have diabetes, obesity and other metabolic diseases, according to findings published in Endocrine Reviews.
In a review of studies on walkable living environments and their impact on metabolic health, most evidence suggests residing in a more walkable neighborhood can reduce the risk of developing diabetes and obesity. Gillian L. Booth, MD, MSc, scientist at the MAP Centre for Urban Health Solutions at St. Michael’s Hospital in Toronto and professor in the department of medicine at the University of Toronto, said the evidence can be used to create policies for improving existing neighborhoods and informing urban planning.
“Where you live matters and it can have a profound impact on your health,” Booth told Healio. “There’s a profound body of evidence now that where you live, how supportive your neighborhood is for walking, being physically active and using more active forms of transportation has an impact on your risk of developing metabolic diseases.”
The researchers analyzed studies assessing built environment, defined as all physical structures in the environment made or modified by humans, and how it influences different aspects of metabolic health. The review focused on studies assessing differences in metabolic outcomes among people living in areas promoting active forms of transportation such as walking and cycling vs. areas promoting the use of cars.
Walkable neighborhoods improve metabolic health
Most studies in the review found people living in walkable areas had better metabolic health. An analysis of data from 15 cities in Canada revealed the prevalence of overweight and obesity among young and middle-aged adults was 43% in those living in high walkability areas vs. 53% for those living in low walkability areas. In the Multi-Ethnic Study of Atherosclerosis (MESA) in the U.S., people who moved to a more densely populated neighborhood had a modest reduction in BMI. However, some studies, such as the Coronary Artery Risk Development in Young Adults (CARDIA) study, did not find a change in BMI associated with neighborhood walkability.
Some studies found associations between neighborhood walkability and markers of glycemic control and insulin resistance. A study of 1.1 million adults living in urban centers in Ontario, Canada, found the incidence of prediabetes was 20% higher among immigrants residing in the least walkable areas compared with those living in the most walkable areas. A number of studies have also suggested neighborhood walkability reduces the odds for developing diabetes. In an analysis of administrative health care data of adults living in Toronto, long-term residents and recent immigrants residing in low walkability areas were 30% to 50% more likely to develop diabetes compared with those in high walkability areas. In another study of young and middle-aged adults in southern Ontario, those living in the highest walkability neighborhood had substantially lower rates of diabetes as well as overweight and obesity.
Several studies also found associations between neighborhood walkability and hypertension. A population-based Canadian study found moving from an unwalkable neighborhood to a highly walkable one was associated with a 54% lower likelihood for hypertension over 10 years. Similar findings were observed in an analysis of the Residential Environment and Coronary Heart Disease (RECORD) cohort in France, data from the UK Biobank and in the CARDIA study. However, most studies have not found any associations between neighborhood walkability and markers of dyslipidemia.
Assessing other environmental factors
Numerous studies have linked metabolic health to neighborhood walkability, but other environmental factors can play a role in health outcomes. Neighborhood income has the potential to cause disparities in studies of built environments, and the researchers noted policies often target economically privileged areas, which may further health inequities.
The availability of healthy food can have a direct impact on metabolic health. Data from the New York City Community Health Survey found the percentage of neighborhood food retailers selling fast food was directly connected to BMI in areas with low levels of poverty. In Toronto, neighborhoods where fast food companies made up the majority of food retailers had 2.5 times higher obesity rates and 1.7 times higher diabetes rates among young and middle-aged adults compared with the general population.
High air pollution can also increase risks for diabetes and hypertension. One Canadian study showed that people living in city neighborhoods that were more walkable were 25% less likely to be diagnosed with diabetes and 35% less likely to be diagnosed with hypertension if there were low levels of traffic-related air pollution. Several studies also found that more green space near people’s homes is associated with a lower BMI and reduced odds for obesity and diabetes.
Booth said research examining built environmental impacts on metabolic health should account for these variables.
“We definitely need to be thinking about the bigger picture,” Booth said. “As researchers, we need to think about how these things work together. It’s not just about changing one thing in the environment.”
Although more research is needed to further explore the impact of walkability on metabolic health, Booth said, policymakers can use existing evidence to begin making smarter and more equitable urban planning policy decisions.
“We can look at how we are designing neighborhoods,” Booth said. “We can also think of the existing landscape we live in and give more opportunities to people, whether it’s more bicycle paths or more walking paths, trying to connect green space to make it easier for people to get outdoors or changing zoning for people to walk places. A big part of it is public transit. If you don’t have the opportunity to use other forms, you’re going to jump in the car. How we build up all of those opportunities and make it easy and safe and attractive for people to use those options is what we need to be thinking about.”
For more information:
Gillian L. Booth, MD, FRCP, can be reached at gillian.booth@unityhealth.to.
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