In the short term, we can work to regulate chemical obesogens. Japan and Canada are phasing out BPA, and now several states in the U.S. are considering following suit. Without labeling laws, the best consumers can do is to avoid polycarbonate-containing plastics, those stamped with the recycling number 3 or 7. But obesogens will still exist in the environment. The larger benefit of studying them, Blumberg says, may be an increased focus on ways to prevent, rather than treat, obesity. "If, as we believe, chemicals to which we are exposed are altering our metabolism to promote the development of fat cells, this should also remove some of the onus that physicians put on patients," he says. "It is not simply always the case that people are obese because they eat too much and exercise too little."