A new federal report shows that more Americans are obese despite an overall increase in the rate of regular exercise.
The National Center for Health Statistics found that 31.4 percent of Americans over the age of 20 were obese in 2017. That's up from 19.4 percent who were obese in the 1997 version of the study.
At the same time, the number of Americans getting regular exercise has increased. In 2017, 53.8 percent of Americans met physical activity guidelines recommended by the federal government, up from just 41 percent who met those guidelines as recently as 2005.
Scientists at the National Center for Health Statistics, an agency housed within the Centers for Disease Control and Prevention said there is no way to decipher whether the figures show that those who are obese are working out more, or if it is only those who do not qualify as obese who tend to get more exercise.
But, they said, most experts will say that a healthy diet is a more integral part of weight loss than going for a jog.
"A dietician will tell you that nutrition is 70 percent of what contributes to weight loss," said Tainya Clarke, a health statistician at the center. "Obesity is the result of complex interactions."
David Katz, director of the Yale University Prevention Research Center, said changes in Americans' dietary habits are fueling rising obesity rates.
"The ubiquity of energy-dense, hyperpalatable foods literally engineered to be addictive make this a virtual truism of modern living: It is far easier to out-eat almost any level of exercise than to outrun the effects of what most of us eat," Katz said.
"Our culture peddles exercise, and people do buy in," Katz said. "But our culture also peddles soda, and all-you-can-eat buffets, and more is better, and multicolored marshmallows as part of a complete breakfast. And ever-rising obesity rates are the predictable and obvious result."
Obesity rates are worst among men between the ages of 40 and 59, almost 38 percent of whom qualify, according to the figures released Thursday. Obesity rates are lowest among men between 20 and 39 – just a quarter of younger men are obese. Minorities tend to have higher obesity rates than whites, in part because those at the lower end of the economic spectrum have less access to healthy foods.
The data also found that exercise rates tend to fall over time. Almost two-thirds of those under the age of 25 met federal physical activity guidelines last year, while just 30 percent of those over the age of 75 met the same requirements, according to the study.
The latest annual survey does have its positive points. Clarke pointed to the prevalence of diabetes, which has plateaued in recent years, while smoking rates are down, vaccination rates are up and more Americans than ever are getting tested for diseases like HIV.
Cigarette smoking rates have fallen by 10 percentage points over the last two decades; today, just 14 percent of adults over the age of 18 are current cigarette smokers, down from nearly a quarter in 1997.
"That's the direction we want it to go in," Clarke said of smoking levels.
Despite the rising obesity rates, Americans are just as likely to say they are in excellent or very good health as they were two decades ago. About two-thirds of Americans describe themselves that way in this year's survey, a number that has hardly changed over time.