America is fat and getting fatter. Today 140 million American adults are overweight or obese. Their bodies carry 4 billion pounds of excess fat, the result of eating 14 trillion excess calories. Numbers of this size belong in the domain of economists, not physicians. And therein lies the solution. Medical and public health attempts to control obesity should continue, but it is time to add marketplace approaches. The first step is realizing that, nationally, weight gain is not a medical problem, it's a pollution problem.