If obesity rates remain at 2010 levels, savings in projected medical expenditures would be $549.5 billion, according to a study released Monday.

The study in the American Journal of Preventive Medicine, led by Eric Finkelstein of Duke University, suggests that by 2030, 42 percent of American adults will be obese, and 11 percent will be severely obese. Earlier forecasts suggested that 51 percent of American adults would be obese by 2030.

Obesity is a body mass index (BMI) of 30 or more. Severe obesity is a BMI of 40 or more.

The study was conducted in 2009 through 2010 and used 1990 through 2008 data from the Behavioral Risk Factor Surveillance System, a federally funded telephone system.

Researchers estimate a 33 percent increase in obesity prevalence and a 130 percent increase in severe obesity prevalence during the next two decades. If those forecasts turn out to be accurate, efforts for health care cost containment will be hindered further, researchers report.

However, variables such as increased access to recreational facilities, improvements in urban design, anti-obesity social marketing programs, worksite health promotion programs, new drugs and technologies could slow obesity growth even further than the forecasts predict, researchers note in the study.