Think the nation's obesity epidemic belongs to the slouch sitting next to you? Think again. A new study suggests nearly two-thirds of Palmetto State residents could be obese by 2030.

In a state that already is among the nation's fattest, the prediction translates into serious healthcare implications and ballooning public health costs over the next two decades.

The new figures are included in "F as in Fat: How Obesity Threatens America's Future 2012," a report released today by Trust for America's Health and the Robert Wood Johnson Foundation.

“This study shows us two futures for America’s health,” said Risa Lavizzo-Mourey, MD, Robert Wood Johnson president and CEO. “At every level of government, we must pursue policies that preserve health, prevent disease and reduce healthcare costs. Nothing less is acceptable.”

Already, 30 percent of Palmetto State residents tip the scales with a body mass index greater than 30. The study predicts South Carolina's rate will climb to 63 percent by 2030, if no action is taken.

Mississippi leads the nation with 34 percent of its population being classified as obese in a state-by-state study of obesity. Colorado has the lowest rate. This study showed a national average below 30 percent.

However, in a separate national survey, the average was reported as 35 percent, according to the Centers for Disease Control and Prevention.

In 2008, medical costs associated with obesity were estimated at $147 billion; the medical costs for people who are obese were $1,429 higher than those of normal weight.

The report is encouraging government to take action to encourage the public to get off the couch and to eat a better diet.

If BMIs were lowered by 5 percent (roughly 10 pounds), South Carolina could save 7.4 percent in health care costs, which would equate to savings of $9,309,000,000 by 2030, the study finds.

The study encourages better nutrition and physical activity among youngsters. School lunch programs, physical education requirements, vending machine regulations and other key parts of children's health need reform, the study suggests.

Edited 8:05 a.m. Sept. 19 to clarify the difference between the national average obesity numbers and the state average obesity numbers, which come from two separate studies.