Big gains in physical activity were seen in counties in Kentucky, Georgia and Florida, but Kentucky's Lewis County also had the biggest increase in male obesity -- from about 29 percent in 2001 to about 45 percent in 2009. Western states claimed some of the most active counties, with residents of Wyoming's Teton County the most active of all -- with about 78 percent meeting recommended exercise guidelines.
Six of the eight least active counties were in Mississippi.
Increases in physical activity suggest that many communities have successfully adopted healthier lifestyles, likely through policies that promote physical activity, Dwyer-Lindgren said.
It is worth considering how these counties have so dramatically improved physical activity levels, Dwyer-Lindgren added. Work on the World Health Organization's Global Burden of Disease project suggests that 234,000 deaths could be averted through more physical activity, Dwyer-Lindgren said.
Samantha Heller, a senior clinical nutritionist at NYU Langone Medical Center in New York City, said it's not surprising exercise alone hasn't whittled down the nation's burgeoning obesity statistics.
Not that exercise doesn't help. "Cardiovascular and resistance exercise keeps bones and muscles strong, boosts brain power, amps up energy levels, turns back the clock on physiological aging [and] reduces the risk of chronic diseases," she said. Physical activity also helps to alleviate anxiety, improve glucose control, manage weight and improve longevity, she noted.
"There is just no down side to exercise," Heller said.
The prevalence of overweight and obesity is in part generated by an environment replete with processed, fast and junk foods that are saturated with fat, sugar and sodium and marketed as cheap and convenient, she said.
Strides have been made to encourage eating fresh, whole foods, cooking at home and daily physical activity, Heller said. "But we need to do more," she added.
Dwyer-Lindgren's team used data on about 34,000 adults from the Behavioral Risk Factor Surveillance System, a state-based telephone survey that covers most counties in the United States, and the National Health and Nutrition Examination Survey.