People in 'Active Cities' Are Slimmer

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Cities and states with more sidewalks and bike paths tend to have slimmer residents than locations where people must rely on non-active, car transportation, a new study finds.

Those cities with the highest levels of active commuting and lower obesity rates tended to be the older U.S. cities with well-developed public transit systems in the Northeast (Boston, New York and Washington, D.C.) and on the West Coast (Seattle and San Francisco). More than 10 percent of work trips in these cities involved walking or biking, said study researcher David Bassett, of the Obesity Research Center, University of Tennessee, Knoxville.

"U.S. cities with the lowest levels of ped-bike commuting were newer cities affected by urban sprawl, such as Dallas, Ft. Worth, Arlington, Jacksonville, Nashville, Indianapolis, Oklahoma City and Charlotte," Basset wrote in an e-mail to LiveScience. These cities reported having just 1 percent to 2 percent of work trips involving active travel.

The study, published online today in the American Journal of Public Health, adds to the mounting evidence showing active travel has significant health benefits, Bassett said.

And infrastructure can help. "People who live in areas that are more conducive to walking and cycling are more likely to engage in these forms of active transport," Bassett and his colleagues wrote.

Couch potato vs. active cities

Bassett and his colleagues analyzed data from all 50 U.S. states and 47 of the 50 largest U.S. cities, along with international data from 14 countries. While the international data included the percentage of all trips taken by walking and cycling, the city and state comparisons used the percentage of work trips that were active. They also looked at overall physical activity, obesity and diabetes.

Results showed that walking and cycling rates could explain more than half of the differences in obesity rates among countries, and about 30 percent of the difference in obesity rates among cities and states.

States with higher rates of walking and cycling had a higher percentage of adults who met the recommended levels of physical activity, a lower percentage of obese adults, and a lower percentage of adults with diabetes.

Overall, the United States doesn't measure up well, coming in at No. 12 out of 14 on percent of trips adults take by bike or foot. Australia came in last, though that data looked at percent of work trips that were active not total trips.

The most active countries (these countries also showed the lowest self-reported obesity rates) were:

  • Switzerland: 50 percent of trips by bike or foot
  • Netherlands: 47 percent
  • Spain: 35 percent
  • Sweden: 32 percent
  • Germany: 32 percent

"European countries with high rates of walking and cycling have less obesity than do Australia and countries in North America that are highly car-dependent," the researchers wrote.

Slimming down cities

The researchers suggest that in addition to infrastructure improvements, cities and states should create restrictions on car use, such as car-free zones, reductions in motor vehicle speeds, and limited and more expensive car parking.

"Moreover, land-use policies should foster compact, mixed-use developments that generate shorter trip distances that are more suitable for walking and biking," they wrote.

The study researchers noted the large increases in obesity rates over the past 30 years, with the World Health Organization estimating more than 300 million adults are obese. Expanding waistlines put these adults at increased risk for diabetes, hypertension, cardiovascular disease, gout, gallstones, fatty liver and some cancers.

Jeanna Bryner
Managing editor, Scientific American

Jeanna Bryner is managing editor of Scientific American. Previously she was editor in chief of Live Science and, prior to that, an editor at Scholastic's Science World magazine. Bryner has an English degree from Salisbury University, a master's degree in biogeochemistry and environmental sciences from the University of Maryland and a graduate science journalism degree from New York University. She has worked as a biologist in Florida, where she monitored wetlands and did field surveys for endangered species, including the gorgeous Florida Scrub Jay. She also received an ocean sciences journalism fellowship from the Woods Hole Oceanographic Institution. She is a firm believer that science is for everyone and that just about everything can be viewed through the lens of science.