Whether your neighborhood is old or new — and thus more friendly to pedestrian traffic or to car travel — may help determine if you're overweight, according to University of Utah research.

The study, to be published in September's American Journal of Preventive Medicine, found that neighborhoods built a half-century or more ago were designed with "walkability" in mind. And living in them reduces an individual's risk of becoming overweight or obese.

Density, diversity and pedestrian-friendly design are the essentials of creating walkable neighborhoods, says Ken R. Smith, demographer, study co-author and professor of family and consumer studies at the U. That matters immensely because by 2030, the researchers say about half of the buildings in the entire country will have been built since 2000. This is the time to impact design to encourage healthy lifestyles.

If you have more residents living in an area, "that is going to make it possible to have things around you that will be attractive to walk to," says Smith. "It makes sense to put businesses where there are a lot of people. If there are other people and places to walk to, walking becomes more attractive."

Diversity means offering a variety of features, he said, citing the new Daybreak development as an example of "trying to engineer diversity by having schools, businesses, residents, parks and a lot of other different types of things all intermingled."

How pedestrian-friendly a place is hinges a lot on traits like whether there are sidewalks and the frequency of intersections. "Intersections are important because if you're walking, they give you options. You can zig and zag and negotiate a path."

If you combine those things right, you have walkability. And that's a key factor in health and well-being, he says. "We are among many who are worried about rising rates of overweight and obesity. There are many, many factors that affect that trend. Our particular purpose is to look at structure and the nature of neighborhoods and see to what extent they contribute to the problem."

The researchers used height and weight information collected by the Driver License Division of the Utah Department of Public Safety and calculated the body mass index (BMI) of more than 450,000 Salt Lake County residents ages 25 to 64, linking it to census-block groups using geographical coordinates. Personal information was stripped away before they got the data, to protect confidentiality.

They found that a man of average height and weight (6 feet, 200 pounds) weighed 10 pounds less in walkable neighborhoods than in less walkable ones. The average woman (5-foot-5, 149 pounds) weighed six pounds less.

"In a perfect world, you could snap your fingers and rearrange neighborhoods in ways that are more walkable, with other objectives like conserving energy, not destroying the environment, along with the obesity objective."

Smith said that older neighborhoods, independent of other factors like race and income, which also affect obesity risk, consistently have lower rates.

Porches on bungalows in downtown Salt Lake City, for instance, face the road (unlike newer backyard decks that put people away from others), and the sidewalks are often shady and pleasant, with a parking strip between them and the road, to improve safety.

Smith conducted the study with three other U. professors of family and consumer studies: Barbara Brown, Cathleen D. Zick and Jessie X. Fan, as well as assistant professor Lori Kowaleski-Jones and assistant professor of geography Ikuho Yamada.

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