Newswise — The age of your neighborhood may influence your risk of obesity, according to a new study from the University of Utah. The study, to be published in the September issue of the American Journal of Preventive Medicine, linked the body mass index (BMI) of nearly a half million Salt Lake County residents to 2000 Census data. The study found that residents were at less risk of being obese or overweight if they lived in walkable neighborhoods—those that are more densely populated, designed to be more friendly to pedestrians and have a range of destinations for pedestrians. The study found that neighborhoods built before 1950 tended to offer greater overall walkability as they more often were designed with the pedestrian in mind, while newer neighborhoods often were designed to facilitate car travel. Demographer Ken Smith, co-author of the study and professor of family and consumer studies at the University of Utah, says that although individuals clearly make personal decisions that influence their weight, neighborhood characteristics also play a potentially important role in affecting residents' risk of obesity. "It is difficult for individuals to change their behavior," he says, "but we can build environments that promote healthy behavior." Using height and weight data collected by the Driver License Division of the Utah Department of Public Safety, Smith and colleagues calculated the BMI of 453,927 Salt Lake County residents age 25 to 64, linking it to census-block groups via geographical coordinates. To protect confidentiality, all personal information from the Driver License Division was removed before the data were provided to the researchers. The study was approved by the University of Utah Institutional Review Board. The study found that a man of average height and weight (6 feet, 200 pounds) weighed 10 pounds less if he lived in a walkable neighborhood versus a less walkable neighborhood. A woman of average size (about 5-foot-5, 149 pounds), weighed six pounds less. "The data show that how and where we live can greatly affect our health," says Smith. According to the study, during 2003-2004 roughly 70 percent of men and 61 percent of women in the U.S. were overweight. The study also notes that by 2030, about half the buildings in the U.S. will have been built since 2000. How this growth occurs will have a significant impact on the environment and on the health of the people living in it, Smith says. "We have the opportunity, using evidence-based data on community design, to create neighborhoods that encourage less car driving, benefiting residents' health and wallets and shrinking our own carbon footprint," says Smith. Neighborhoods with higher percentages of pedestrian traffic—something the study found is associated with less obesity among residents—can serve as models for future residential development and redevelopment. "Neighborhoods with higher fractions of residents that walk to work tell us that something beneficial about the neighborhood is promoting health," notes Smith. "We expect these results mean that residents find walking more attractive and enjoyable where there are other walkers, a variety of destinations easily accessible by foot and pedestrian-friendly street networks. People want to walk when it's pleasant, convenient and when there is a destination." Smith conducted the study with three other University of Utah professors of family and consumer studies—Barbara Brown, Cathleen D. Zick and Jessie X. Fan—and one assistant professor, Lori Kowaleski-Jones, along with Ikuho Yamada, assistant professor of geography.