MONDAY, May 7 (HealthDay News) -- Even if the skyrocketing rates of obesity level off, 42 percent of Americans will be obese and 11 percent will be severely obese by the year 2030, a new report predicts.

That means 32 million more people will be tipping the scales in the wrong direction, costing the country billions, according to the study, appearing online May 7 in the American Journal of Preventive Medicine.

The (slightly) good news is that the number of people becoming obese may not be increasing as much as previously thought.

"There's some evidence that the curves of increase in obesity may have changed and, at best, may be a plateau," Dr. William Dietz, director of the division of nutrition, physical activity and obesity at the U.S. Centers for Disease Control and Prevention, said during a Monday news conference. "[But] we still have a very serious problem."

The computer model devised by report author Eric Finkelstein and his colleagues also predicted that the prevalence of severe obesity would more than double from 5 percent to 11 percent.

If these new estimates prove true, obesity will cost the country some $550 billion, the report stated.

"Prior publications suggest that by the year 2030 or 2050, we're going to see obesity prevalences well above 50, 60 or even 70 percent," said Finkelstein, who is an assistant director of the Health Services and Systems Research Program at Duke-National University of Singapore Graduate Medical School.

But these estimates have assumed that obesity rates are going to keep rising at the same rate they have been.

The current study takes into account signs that the rates of increase may be slowing.

Taking both national and state data on adults aged 18 and over from 1990 to 2008, the researchers estimated a 33 percent increase in the prevalence of obesity in 2030, less than previously estimated.

The new estimates combined with varying previous estimates "reflect the amount of uncertainty we have with regard to how things are changing," said Dietz.

On Tuesday, the Institute of Medicine will release a report outlining possible solutions to the problem.

These may include workplace wellness initiatives, the authors stated.

More information

The U.S. Centers for Disease Control and Prevention has more information on overweight and obesity.