The number of states with an adult obesity rate of at least 30 percent remained unchanged from the previous year, but a new study says adult obesity rates could exceed 60 percent in 13 states by 2030.

The "F as in Fat: How Obesity Threatens America’s Future 2012" report was recently released by the nonprofit organization Trust for America’s Health and the Robert Wood Johnson Foundation (RWJF). This is the first year that the annual report has projected obesity rates based on state-by-state data from the Centers for Disease Control and Prevention (CDC).

Not only could there be 13 states with adult obesity rates of 60 percent or above by 2030, but if obesity rates continue on their current trajectories, 39 states could have rates above 50 percent, and all 50 states could have rates above 44 percent, according to the report. By 2030, Mississippi could have the highest obesity rate at 66.7 percent, and Colorado could have the lowest rate for any state at 44.8 percent.

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

The number of states with an adult obesity rate of 30 percent or above in 2011 was 12, the same number as the previous year. For the first time, all 50 states plus the District of Columbia were at 20 percent or above.

For the eighth consecutive year, Mississippi has the highest adult obesity rate at 34.9 percent, an increase from 34.4 percent from the previous year. For the ninth consecutive year, Colorado has the lowest adult obesity rate at 20.7 percent, an increase from 19.8 percent from the previous year. By comparison, Mississippi had the nation’s highest adult obesity rate in 1995 at 19.4 percent.

If states’ obesity rates continue on their current paths, the number of new cases of type 2 diabetes, coronary heart disease and stroke, hypertension and arthritis could increase 10 times between 2010 and 2020, and double again by 2030, according to this year’s study. Obesity could contribute to more than 6 million cases of type 2 diabetes, 5 million cases of coronary heart disease and stroke, and more than 400,000 cases of cancer in the next two decades.

By 2030, medical costs associated with treating preventable obesity-related diseases are estimated to increase by $48 billion to $66 billion per year in the United States, and the loss in economic productivity could be between $390 billion and $580 billion annually by 2030, according to the study. Current estimates of the medical cost of adult obesity in the United States range from $147 billion to nearly $210 billion per year, although the study notes that medical cost estimates can be difficult to calculate.

The states with the highest adult obesity ranking, based on 2011 data, are:

1. Mississippi (34.9 percent)
2. Louisiana (33.4 percent)
3. West Virginia (32.4 percent)
4. Alabama (32 percent)
5. Michigan (31.3 percent)
6. Oklahoma (31.1 percent)
7. Arkansas (30.9 percent)
8. (tie) Indiana (30.8 percent)
8. (tie) South Carolina (30.8 percent)
10. (tie) Kentucky (30.4 percent)
10. (tie) Texas (30.4 percent)
12. Missouri (30.3 percent)

The states with the highest projected adult obesity rankings by 2030 are:

1. Mississippi (66.7 percent)
2. Oklahoma (66.4 percent)
3. Delaware (64.7 percent)
4. Tennessee (63.4 percent)
5. South Carolina (62.9 percent)
6. Alabama (62.6 percent)
7. (tie) Kansas (62.1 percent)
7. (tie) Louisiana (62.1 percent)
9. Missouri (61.9 percent)
10. Arkansas (60.6 percent)
11. South Dakota (60.4 percent)
12. West Virginia (60.2 percent)
13. Kentucky (60.1 percent)