On Friday the Centers for Disease Control and Prevention issued a startling report about beverage consumption. American teens, the report concludes, drank less sugary soda last year than in 2009—a lot less. The number of high school-age U.S. soda drinkers dropped by 5 percent in just one year. If soda taxes are really all about nudging us—and especially our kids—into giving up soft drinks, it seems that result has already been achieved without the use of punitive taxes.

According to the CDC’s Morbidity and Mortality Report from June 17, soda isn’t even among the three most frequently consumed drinks among American teens. Here are the percentages of high school students who reported drinking at least one serving per day of different beverages during a one-week period last year (the top five are shown, rounded to the nearest percentage point):

Water

72% of students

Milk

42%

100% fruit juice

30%

Soda

24%

Sports drinks

16%

And yes, soda consumption is on the decline. (Last year, that number was 29 percent.)

In another CDC study, also issued Friday, researchers looked at how many high school students were meeting the government’s minimum goals for strength-training and “aerobic” physical activity. The results are eye-opening.

Here are the percentages of high school students meeting both of those minimum standards (rounded to the nearest percentage point):

Ninth grade

15% “passed”

Tenth grade

12%

Eleventh grade

11%

Twelfth grade

10%

OVERALL

12%

Notice anything odd, other than the fact that teens get more and more sedentary with each passing year? Eighty-eight percent of U.S. high school students are cultivating habits that will leave them out of shape. That’s more than three times as many as those regular soda drinkers.

Anyone who looked at these numbers with a level head (and a grade-school education) would conclude that the bigger problem—and the more likely reason for kids being overweight—is not a shiny cylinder with a pop-top. It’s the fact that teens aren’t moving their bodies very much.

But then there’s Yale University’s Kelly Brownell, the godfather of the “Twinkie Tax” (and other preschool-level ideas). Brownell is sticking to his soda-taxing guns, telling the Philadelphia Inquirer that artificially raising the price of soft drinks as a behavioral tool is an idea whose time will eventually come.

Nonsense.

Right now, Philadelphia’s recently defeated soda-tax proposal is a comedy of errors. Mayor Michael Nutter originally proposed it as a public-health tool, but now he’s admitting that it’s all about raising $80 million in new government revenues. Sure, the funds are supposedly earmarked for education—but how much of that money do you think will buy new exercise equipment, hire physical education teachers, or create new sports teams?

Does “zero” sound about right?

Here’s a memo for Kelly Brownell and Mayor Nutter: Fewer teens are drinking soda, and new taxes had nothing to do with it. We’re confident that eventually you’ll think of a way to tax sweat. But for now let’s tackle a truly big problem—our collective lack of exercise—before we spend time, money, and political capital on the small ones.