It looks like San Francisco mayor Gavin Newsom is making an early bid for next year’s Worst Nanny Award. Last Friday Newsom announced a plan to implement what has quickly become the latest big-government “solution” to rising obesity rates: special taxes on soft drink sales at large retailers.

Newsom (a politician, not a scientist) claims there’s a “direct nexus” between childhood obesity and the high-fructose corn syrup (HFCS) found in many sweetened drinks. Funds collected from the new tax -- or, as Newsom spins it, the “small fee” -- would go toward city-run anti-obesity programs which have so far been laughably ineffective at changing kids’ eating behavior.

What about the “direct nexus”? A major study published earlier this month shows that consuming HFCS has the same physical effect as drinking a glass of milk. And the urge to drink sodas won’t go away with the stroke of a mayoral pen. If sugary drinks sold at large stores get too expensive, kids will just buy them somewhere else.

Interestingly, Newsom’s PR flacks have been quick to assure voters that the mayor has no plans to tax other tasty treats popular among schoolkids, like pizza, Twinkies, and HoHos. But why stop at irresponsibly scapegoating just one food? Taxing everything that’s not celery would be an easy way to fill up the city’s coffers without actually addressing why kids become obese. As an editorial in today’s San Francisco Chronicle argues:

[T]here is also something unhealthful about a politician's attempt to selectively target one source of calories for a new tax … 

Government could drive itself crazy trying to calculate the societal cost of a bag of Cheetos, a bucket of extra-crispy fried chicken or a sumptuous serving of tiramisu at the end of a four-course meal.