Natural environment linked to reduced obesity

New research from North Carolina finds that people who live in counties with better weather and more natural features like hills and lakes are more active and thinner than their counterparts, even when researchers take other factors into consideration.

The findings do not prove that natural features affect how much exercise people get or how much they weigh. However, the study results do raise questions that further research can explore, said lead author Stephanie Jilcott, an assistant professor at the Department of Public Health at East Carolina University.

"We're trying to figure out whether the places themselves encourage activity or people who want to be active move to these places," Jilcott said. She added that such research could encourage discussion about how to better link people with natural amenities − like lakes − that could boost their physical activity.

The study authors examined statistics about the average weight of residents in 100 North Carolina counties and tried to link them to rankings of the weather and the presence of natural features like lakes and hills. The researchers adjusted their statistics, compiled from 2000 to 2007, so that factors like poverty level, participants' age or the percentage of rural and African-American residents in each county would not throw off the results.

The results appear in the September/October issue of the American Journal of Health Promotion.

Body mass index (BMI) is a measurement used to determine whether people are overweight. In adults, normal BMI is 18.5 to 24, while experts consider 25 to 29.9 to be overweight and 30 and over to be obese.

For the study, Jilcott said, the average body mass index was 0.47 points higher in counties with the lowest natural amenity scores compared to those with the highest. This might not make much difference to an individual, she said, but it is more significant in total across a community.

However, the statistics in the study did not offer a breakdown of how many exercised in, say, a gym instead of outside. Also, "it could be that people who like to exercise or pay more attention to their diets choose to live in places that support their lifestyle," said Dr. Deborah Cohen, a senior natural scientist at RAND Corporation who studies how the environment affects health and is familiar with the new research.

Cohen said that people often inaccurately describe their level of physical activity, usually saying they get more exercise than they actually do.

What do the study findings mean in practical terms? "There's nothing we can do to change the natural environment," Jilcott said. "It is what it is, but county leaders may want to assess what elements of natural amenities that could be enhanced. For example, if the county is flat, but has access to water, parks and recreation departments could attempt low-cost investments in encouraging residents to be active in and around the water."