Obesity rates in the United States will continue to rise over the next two decades, a new study says.

By 2030, 42 percent of people in the U.S. will be obese, meaning 32 million more people will become obese in the coming years, the study found. Currently, about 34 percent of adults and 17 percent of children are obese.

The percentage of Americans who are severely obese, defined those carrying more than 80 pounds of extra weight, will increase from 5 percent to 11 percent by 2030, the researchers from Duke University said.

While previous predictions had suggested obesity rates could reach 50 percent or more by 2030, these were based on the steep rise in obesity rates seen in previous decades. However, more recent data suggest obesity rates have been leveling off.

The new study identified variables that may predict obesity, such as changes in the country's demographics, changes in the price of healthy and fast foods, and the number of fast-food restaurants. The researchers then modeled how changes in these variables could lead to changes in the country's obesity rate.

Still, the researchers noted predicting obesity rates is tricky, and the real percentages could differ if their assumptions do not hold true.

The findings were presented today (May 7) at the Center for Disease Control and Prevention's Weight of the Nation Conference in Washington, D.C.

Pass it on:  Forty-two percent of the American population will be obese by 2030, according to new estimates.

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