Healthcare costs related to obesity total more than $190 billion is spent annually - - more than double previous estimates, according to a new study. Reuters

Obesity is a growing problem in the United States, and as waistline girth expands, so does the costs of managing healthcare -- and that cost has been heavily underestimated, according to a new study. Researchers found the annual medical costs of obesity are more than double previous estimates.

An obese person's annual medical cost is $2,700 higher, in 2005 dollars, than a non-obese person, according to the study. In 2010 dollars, the last year data is available, that is equivalent to almost $3,000.

More than 35 percent of adults in the U.S. older than 20 are obese. In 1985, no state had an obesity rate higher than 14 percent. By 2010, no state had an obesity rate lower than 20 percent, according to the Centers for Disease Control and Prevention.

Costs associated with obesity accounts for $190 billion annually -- 121 percent higher than previous estimates. More than 20.6 percent of all national health expenditures is spent on managing obesity and the related plethora of health problems, researchers said.

Historically we've been underestimating the benefit of preventing and reducing obesity, John Cawley, lead researcher and professor of economics at Cornell University, said in a statement. Obesity raises the risk of cancer, stroke, heart attack and diabetes. Obesity raises the costs of treating almost any medical condition. It adds up very quickly.

The majority of money is spent comes from those who are more than 100 pounds overweight. The five percent of Americans who are morbidly obese spend by far the most on healthcare, researcher said.

They were critical of previous studies that simply reported the difference between the medical expenses of obese and non-obese people. People who gain weight as a result of an injury shouldn't be counted, but often are, they said.

For example, I could have injured my back at work, and that may have led me to gain weight, Cawley said. The injury could have led to a lot of health care costs that are due to my back, not my obesity.

The findings underscore the need for the government to provide more funding for anti-obesity programs, the researchers wrote. They also found the increase in obesity is linked to increased Medicaid costs, suggesting that, regardless of weight, everyone is paying for obesity through higher taxes.

That means that obesity isn't just a personal issue, Cawley said. This is relevant to all of society, because the health care costs of obesity are borne by the population as a whole.

The study was published in the Journal of Health Economics.