LOS ANGELES - Obesity rates in the United States climbed over the past year in 16 states, and not a single state reported a decline in the proportion of excessively overweight residents, according to a report released on Thursday.

The report, published by HealthDay News, found that more than 30 percent of the people in 12 states are obese. Four years ago, only one state could make that claim.

Twenty years ago, "there wasn't a single state that had an obesity rate above 15 percent, and now every state is above that," said Jeff Levi, executive director of Trust for America's Health, which compiled the report.

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"We have seen a dramatic shift over a generation," he added. " This isn't just about how much people weigh, but it has to do with serious health problems like diabetes and hypertension. These are the things that are driving health care costs."

With the exception of Michigan, the 10 most obese states are in the South. The Northeast and West reported the lowest obesity rates. In addition, in eight states, more than 10 percent of adults suffer from type 2 diabetes, according to the report.

Mississippi, where 34.4 percent of the people are obese, has the highest obesity rate. Other states with obesity rates above 30 percent include: Alabama, Arkansas, Kentucky, Louisiana, Michigan, Missouri, Oklahoma, South Carolina, Tennessee, Texas and West Virginia. Thirty-eight other states have obesity rates above 25 percent.

For the second year in a row, obesity rates rose in Illinois, Kentucky, Massachusetts, Missouri, Rhode Island and Texas.

And, for the third year straight, more residents of Florida, Kansas, Maine, Oklahoma and Vermont tipped the scale toward obesity.

Colorado, with an obesity rate of 19.8 percent, is the only state where the rate is less than 20 percent, the report found.

The study also found that more than one-third of children and adolescents are obese or overweight, with the highest prevalence in the South. However, the new data indicate that obesity among children and adolescents may have leveled off, except among the heaviest boys.