Obesity has reached epidemic proportions in the United States and other developed nations. In the United States, 27% of adults are obese and an additional 34% are overweight. Research in the past decade has shown that genetic influences clearly predispose some individuals to obesity. The marked increase in prevalence, however, appears to be attributable to a toxic environment that implicitly discourages physical activity while explicitly encouraging the consumption of supersized portions of high-fat, high-sugar foods. Management of the obesity epidemic will require a two-pronged approach. First, better treatments, including behavioral, pharmacologic, and surgical interventions, are needed for individuals who are already obese. The second and potentially more promising approach is to prevent the development of obesity by tackling the toxic environment. This will require bold public policy initiatives such as regulating food advertising directed at children. The authors call not for the adoption of a specific policy initiative, but instead propose that policy research, based on viewing obesity as a public health problem, become a central focus of research.