Americans claim that they exercise, but more are obese than ever

So if more Americans are exercising, how can one also become fatter?

Some experts think the results may reflect two groups of people – the haves and the have-nots of fitness, so to speak.

"It is possible that people become more active already have a normal weight," said John Jakicic, director of the Center for Research on the Management of Physical Activity and Weight of the University of Pittsburgh

. 60 years has been an important indicator of health trends in the United States. About 35,000 adults respond to the survey each year, including questions about the frequency, duration, and vigor of their hobbies

The survey gives a good overview of trends, but it is not perfect. According to Jakicic, people overestimate their physical activity, just as they exaggerate their size and weight, he says.

Ten-year-old federal guidelines provide that adults should do weightlifting or other muscle building exercises at least twice a week. They also advise adults to do at least 75 minutes a week of high intensity aerobic activity, such as running, or 150 minutes of moderate intensity exercise, such as brisk walking, or a combination both.

The Centers for Disease Control and Prevention examined responses to the surveys from 2010 to 2015 and found that the level of leisure exercise was more common in some states than in others.

Nearly one-third of Colorado's older adults, Idaho and New Hampshire abided by the exercise guidelines. Only about a seventh in Mississippi, Kentucky and South Carolina did

Higher levels of exercise were more common among people who were working than those who were not working, the # 39 study also found

exercise levels were stable during the years covered by the CDC report. But more recent data show that more adults said that they were exercising at recommended levels in 2016 and 2017.

It's unclear why, said Jena Shaw Tronieri, a weight loss specialist from the University of Pennsylvania. "I do not know if this will explain the rise recently, but we know that these cyclical factors are part of the context," she said.

Of course, unhealthy eating has a lot to do with obesity. Research indicates that "a dietary change is needed to see any bump or reduction in obesity," said Tainya Clarke of the CDC, one of the report's authors.