Mayor Michael Bloomberg's announcement that the city will pursue a ban on large sugary drinks sold at restaurants, movie theatres, and other locations is just the latest attempt in his campaign against obesity--one that has so far met with little success in the face of a powerful food lobby, one sometimes joined by odd bedfellows.

In 2010, when his administration asked the federal government for permission to prohibit New York City food stamp recipients from purchasing sugary drinks with their benefits, the Food Industry Alliance of New York State, a trade group representing New York State grocers and other ...