This is Mississippi's third year in a row topping CalorieLab's United States of Obesity report. The BBC goes to Jefferson County, MS to find out why.
"Tiny Jefferson County Hospital sits on top of a hill on the outskirts of Fayette, opposite a school.
It has a nutrition clinic, but it is conspicuously empty.
A poster advertising a weight loss class is taped to a one wall, urging participants to "Drop them pounds like they hot".
But this is not a message many people want to hear, according to Dr Frank McCune, the county's only obesity expert.
Mississippi is the home of the mud pie, of cajun fried pecans, sweet potato crunch, of fried shrimp and catfish - and Dr McCune says overeating is ingrained into the culture of the area.
"Some deny the fact that obesity is a problem," he says. "Many don't know what it is. Some of them think that being 5'4" (1.64m) tall and 225 pounds (102kg; 16st 1lb) is a normal weight."
Thanks to Governing Magazine