Michelle Obama, for one, must be ecstatic. For the first time in decades, several American cities are reporting declines in childhood-obesity rates. The trend included several of the country’s biggest cities, like New York and Los Angeles, as well as some smaller metro areas like Anchorage, Alaska, and Kearney, Neb. The drops aren’t huge—just 5 percent in Philadelpha and 3 percent in Los Angeles—but, as Dr. Thomas Farley, the health commissioner in New York City says, “It’s been nothing but bad news for 30 years, so the fact that we have any good news is a big story.” It’s not clear what’s behind the declines.
