“Physical activity can be something as simple as walking to the bus stop. That’s another problem, by the way: the South doesn’t have many bus stops. Public transportation is paltry, and for most people, the best way to get around is by car. “You don’t really think of riding the train as exercise, but at least you have to walk a few blocks to get to the stop,” says Bassett. States like Mississippi and Tennessee also have a surprising lack of sidewalks, discouraging even the most eager pedestrians. Many roads are narrower than those in the North — where streets have wider shoulders to accommodate winter snow — and people who want to bike or jog find themselves uncomfortably close to traffic.”
Why Are Southerners So Fat? - TIME
Really quite fascinating.
Other reasons: poverty, the heat, fried foods/high calorie diets.