Nine of 10 states with the highest rates of obesity are in the South, while states in the Northeast and West had lower rates, the report shows. Mississippi had the highest adult obesity rates for the seventh year in a row and Colorado had the lowest (less than 20%).

Twenty years ago, no state had an obesity rate higher than 15%, but today 38 states have obesity rates over 25%. Obesity rates are growing rapidly in Oklahoma, Alabama, and Tennessee and at a slower pace in Washington D.C., Colorado, and Connecticut.

Overall, rates of obesity are highest among members of racial and ethnic minority groups, the study showed. Along with the increase in obesity rates comes a corresponding increase in diseases associated with obesity such as diabetes and high blood pressure.

Since 1995, diabetes rates have doubled in eight states, and every state has high blood pressure rates greater than 20%, and nine have rates above 30%.

There is no single reason that obesity rates are increasing across the board.

"A lot of little changes have added up to that," Marks says. "Portion sizes in restaurants and the size of soft drinks that one can get at convenience stores are much larger," he says. "You can get a 44-ounce drink and that is the equivalent of a six pack when I was growing up."

"Snacking has gone up more and more," he says.

It is difficult to even get healthy foods in some parts of the country, Marks says. "We have cut off physical activity funding in schools and the foods that are subsidized are those that are least healthy for children."