Pennsylvania ranked 19th worst in the percentage of obese adults, with 28.5 percent of the state's population considered obese. New Jersey fared better, with only seven states and the nation's capital having lower obesity rates than its 24.1 percent.
"When you look at it year by year, the changes are incremental," says Jeffrey Levi, executive director of the Trust for America's Health, which writes the report with the Robert Wood Johnson Foundation. "When you look at it by a generation, you see how we got into this problem."
The study says a dozen states topped 30 percent obesity in 2010, most of them in the South. Alabama, West Virginia, Tennessee, and Louisiana were close behind Mississippi. Just five years ago, in 2006, Mississippi was the only state above 30 percent.
No state decreased its level of obesity, which is defined as a body mass index of 30 or more. The body mass index is a measurement based on a calculation using a person's weight and height. A person who is 5 feet 5 inches and weighs 150 pounds would have a body mass index of 25, for example, but if that person weighed 180 pounds, the BMI would be 30.
While body mass index isn't always the best indicator for someone with a lot of muscle, such as an athlete, it is considered the best way to measure the general population.
There was a bit of good news in the report: Sixteen states reported increases in their obesity rates, down from 28 states that reported increases last year.
Levi says those increases have been gradually slowing, most likely due to greater public awareness of health issues and government attempts to give schools and shoppers better access to healthier foods.
Michelle Obama has tackled the issue with her "Let's Move" campaign. And Congress last year passed a law requiring school lunches to be healthier. Republicans in Congress have fought against some of those programs, saying a rewrite of school-lunch rules is too costly and questioning an administration effort to curb junk-food marketing to children.