A state-by-state breakdown shows Americans are getting fatter, with almost one-third of the adult population in 12 states now classified as obese.

The findings are part of a report released Thursday by two private organizations, the Trust for America's Health and the Robert Wood Johnson Foundation.

The report found obesity rates increased in 16 U.S. states from 2009 to 2010. It also found that obesity rates are highest in the southern U.S., home to nine of the 10 fattest states.

Even in the U.S. state with the lowest percentage of overweight adults – the central state of Colorado – almost one out of every five adults is considered obese and at a higher risk for ailments like diabetes and heart disease.

The executive director of the Trust for America's Health says the findings are worrisome. Doctor Jeff Levi warns the increasing obesity rates will have a growing impact on the country's health care spending.

The study also found differences in obesity rates along racial and ethnic lines and among those with different levels of education.

The state-by-state analysis showed Blacks and Latinos had higher obesity rates than whites. It also found one-third of adults who did not graduate from high school are obese, compared to 22 percent of adults who graduated from a two or four year college.