State and municipal innovations in obesity policy: why localities remain a necessary laboratory for innovation.

Municipal and state governments are surging ahead in obesity prevention, providing a testing ground for innovative policies and shifting social norms in the process. Though high-profile measures such as New York City's soda portion rule attract significant media attention, we catalog the broader array of initiatives in less-known localities. Local innovation advances prevention policy, but faces legal and political constraints-constitutional challenges, preemption, charges of paternalism, lack of evidence, and widening health inequalities. These arguments can be met with astute framing, empirical evidence, and policy design, enabling local governments to remain at the forefront in transforming obesogenic environments.