Eating Too Much Is Still Why You're Fat, Despite All That Jogging

Waistlines are growing even as exercise levels increase. Here’s why.

The good news: Americans are exercising more. The bad news: it’s not doing much to reduce obesity rates.

A new study from the University of Washington reveals that the level of women exercising "sufficiently" in the U.S. rose from 50.7% to 59.2% between 2001 and 2011, while the exercise level among men climbed from 59.4% to 61.3%. But in the vast majority of counties, waistlines kept increasing.

The study, which is based on hundreds of thousands of responses collected by the Centers for Disease Control, found only nine counties where obesity levels decreased: five for men, four for women. Overall, one percentage point increase in physical activity led to only 0.11% lower prevalence of obesity.

The researchers say exercise is necessary, but not sufficient to curb obesity, which affects up to one third of Americans. Diet may be as important. "Other changes such as reduction in caloric intake are likely needed to curb the obesity epidemic and its burden," they conclude.

Kentucky, Florida, Georgia, and California had the largest gains in activity. Among the top 10 most improved counties, Kentucky had six for men, and seven for women. Atlanta, Los Angeles, San Francisco, San Diego, Houston, and Denver, were also big climbers. Levels of physical activity were generally lowest along the Texas-Mexico border, and in parts of the deep South.

Obesity levels vary widely. In 2011, the highest levels among women were in Issaquena County, Mississippi (59.3%), and, for men, in Owsley County, Kentucky (46.9%). The lowest levels for women were in Falls Church City, Virginia (17.6%), and for men, San Francisco County, California (18.3%).

Given the lack of impact from increased exercise, the researchers suggest that counties try other approaches, like better food labeling, taxing harmful products, and improving incentive programs.