Editor's note: David Frum is a contributing editor at Newsweek and The Daily Beast and a CNN contributor. He is the author of seven books, including a new novel, "Patriots."

Nobody seems to have a positive word for Mayor Michael Bloomberg's proposal to ban oversized servings of sugary drinks in New York's food-service establishments.

The mayor has been decried as a nanny. He has been accused of selective enforcement. (A Starbucks 20 ounce drink can have more than 500 calories, but will be exempt from the ban because it contains more than 50% milk.) The beverage industry complains that solutions to the obesity problem ought to be more "comprehensive." One important conservative magazine called the mayor's actions a form of "fascism."

So let's defy the trend here and say: Good for Bloomberg. Obesity is America's most important public health problem, and the mayor has led the way against it. This latest idea may or may not yield results. But it is already raising awareness. Even if it fails to become law, it ought to prod the beverage industry into acting as more responsible corporate citizens.

Read - Bloomberg's visionary move against obesity and Controversy fizzing over Bloomberg's soda ban