Newsletter #202

The underlying causes of the obesity epidemic are complex and can’t really be pinned on any single factor, which is why it is such a terrible challenge from a public health standpoint. But one influential variable that has been identified is the built environment, meaning the spaces where we live, work, and engage in leisure activities on a day-to-day basis. This can strongly affect levels of physical activity, especially at a population level. For example, living in a place with sidewalks, and which is in reasonably close proximity to work and other amenities, obviously makes it a whole lot easier to walk places rather than drive.

This, in turn, may help mitigate weight gain, and that can blunt some of the downstream metabolic consequences of obesity over time. For instance, we know that insulin resistance often accompanies obesity, which ultimately leads to the development of type 2 diabetes. Additionally, insulin resistance frequently coexists with high blood pressure, perhaps due to the impact of elevated insulin on sodium absorption by the kidneys.

So, how exactly does “walkability” affect this constellation of conditions that make up metabolic syndrome? To learn how the built environment affects insulin resistance, obesity, type 2 diabetes, and hypertension, scroll on down 👇🏻

Researchers in Ontario examined data from 1,128,181 adults with normal blood sugar at baseline. The walkability of the neighborhood in which every individual lived was analyzed and they were divided into ten categories based on levels of walkability. After following them for an average of eight years, the researchers found that incidence of pre-diabetes was 20% higher among individuals living in the least walkable areas, compared to the most, after adjusting for age, sex, and income. Pre-diabetes is an important window for intervention, as an estimated 70% of those with prediabetes go on to develop type 2 diabetes, but lifestyle interventions (including walking) can effectively reverse that unfortunate trend.

The same research team examined data on transportation behavior, aspects of the built environment, and health outcomes in Toronto residents between 2003 and 2009. They drew upon the Canada census, a transportation survey, a national health survey and a validated administrative diabetes database, and were able to capture walkability by graphically depicting availability of walkable destinations. They found, unsurprisingly, that individuals in the most walkable areas were more than twice as likely to use public transit or active transportation, compared to those in the least walkable areas. Individuals living in the least walkable areas were 18% more likely to be overweight or obese, and 33% more likely to have type 2 diabetes, compared to counterparts in highly walkable areas.

Researchers examined data from participants in a large Canadian health survey, and linked the survey data to a population-based healthcare database that identified hypertension diagnoses. They defined residential walkability for subjects using a walkability score that was based on walking distances to a diverse set of nearby amenities, including grocery stores, restaurants, schools, etc. From there, they compared otherwise similar individuals who had relocated from a low-walkable area to either a 1) highly walkable area or 2) another low-walkable area. They found that those who had moved from an area of low walkability to a neighborhood of high walkability had a 54% reduced risk of developing high blood pressure, compared to those who moved to a low walkability area.

Thanks for reading, as always. If you're looking for more health research, be sure to visit with us on Twitter on @humanOS_me.

https://mailchi.mp/humanos.me/newsletter-202