NEW YORK — A group campaigning against obesity predicts that by 2030 more than half the people in 39 states will be obese — not merely overweight.

The report says Georgia is expected to have a 54 percent obesity rate by 2030. The state currently has a 28 percent rate. Mississippi is expected to retain its crown as the fattest state in the nation for at least two more decades. The report predicts 67 percent of that state’s adults will be obese by 2030; the current rate is 35 percent.

The new projections were released Tuesday by Trust for America’s Health and the Robert Wood Johnson Foundation. The two organizations regularly report on obesity to raise awareness, and they rely on government figures.

Trust for America’s Health officials said their projections are based in part on state-by-state surveys by the Centers for Disease Control and Prevention from 1999 through 2010. Those numbers come from what residents say are their height and weight when asked by interviewers over the phone. People aren’t always so accurate about that.

The researchers then looked at other national data in which residents actually were weighed and measured and they made adjustments for how much people in each state might fudge the truth about their weight. They also tried to apply recent trends in obesity rates, along with other factors, to make the predictions.