First a Soda Tax, Now a Pizza Tax: The Food Police March On

America's nutritional nannies are at it again.

A study published earlier this week by the American Medical Association's Archives of Internal Medicine argues that if pizza and soda were more expensive, people would consume them less frequently in favor of healthier fare. Tacking an 18% tax onto pizza and soda would reduce Americans' intake of calories, which would in turn help slash health care costs by an astounding $147 billion a year, according to the study's authors. Pizza was singled out by the researchers because, like soda, its real price (versus inflation, through 2006) fell over time, while costs for seemingly healthier foods such as whole milk rose over the 20-year period reviewed in the study.

Though I believe that there is an obesity epidemic (I am a statistic myself), I have a tough time believing the study offers much of a solution.

For one thing, pizza isn't especially bad for you, and whole milk is not especially nutritious. Pizza clocks in at about 300 calories for single plain slice, according to CalorieKing: That's not a salad -- which can become an orgy of calories depending on the type of dressing you choose -- but it's not as bad as a McDonald's (MCD) Quarter Pounder, which has 510 calories. Of course, pizza gets more fattening when you add meat-based toppings to it such as peperoni.

As for milk, some experts have questioned whether drinking it is especially good for people. Whole milk is the most fattening variant, with 147 calories in a single serving.

Good Foods Versus Bad Foods: Too Simplistic a View?

For their part, the authors argue that they are not trying to demonize any particular food.

"Our findings suggest that national, state or local policies to alter the price of less healthful foods and beverages may be one possible mechanism for steering U.S. adults toward a more healthful diet," the authors write. "While such policies will not solve the obesity epidemic in its entirety and may face considerable opposition from food manufacturers and sellers, they could prove an important strategy to address overconsumption, help reduce energy intake and potentially aid in weight loss and reduced rates of diabetes among U.S. adults."

Theoretically, the authors are probably right. Making something prohibitively expensive discourages people from doing it. Subsidizing the production of high-fructose corn syrup is not a good idea either, and healthy foods should be more accessible and affordable. But other experts say reducing the fight over obesity to a struggle between good foods and bad foods is overly simplistic.

"I don't think you can single out one food or two foods as a cause of obesity." says Keri Gans, a registered dietitian based in New York and a spokeswoman for the American Dietetic Association. "People love their high-calorie coffee drinks that cost a fortune," though plain coffee is much cheaper.

"It's No One's Business What Anybody Puts in Their Mouths"

The idea of taxing people to better health is gaining popularity. Anti-obesity soda taxes are being discussed in New York and Philadelphia. There is even talk of a levy at the federal level. Both the Centers for Disease Control and Prevention and the American Heart Association support soda taxes. But these taxes are unfair to the poor, who already spend a far greater fraction of their salaries on food than the wealthy. And attempts to change behavior through taxation or legislation don't always produce the desired effects.

For years, smoking rates declined as cigarette taxes skyrocketed. Then the declines stalled, in part because states did not spend enough on smoking cessation efforts The CDC estimates that about 46 million American adults are smokers. Studies of New York City's law mandating that restaurants provide calorie information disagree about whether it is having a positive impact.

Americans are quite ingenious at avoiding laws they don't like. Think about the throngs of people who take special road trips to buy Fourth of July fireworks which are illegal where they live. Delaware advertises itself at the home of "tax-free shopping" because it lacks a sales tax: In theory, out-of-state residents are supposed to declare their Delaware purchases to their home states, but most never bother. At least these items are easily identifiable: Can you imagine the fights that will occur over obesity-prevention taxes if experts can't agree on what is nutritious?

Sallie James, a policy analyst at the libertarian Cato Institute, denounces these types of proposals as paternalistic. "It's no one's business what anybody puts in their mouths," she says in an interview. "I suspect some lawmakers are attracted to it for a revenue source."

Pizza Sellers Ask: Why Pick on Us?

With government budgets being squeezed, she has a point. Of course, obesity is a serious problem. Medical expenses for the overweight accounted for 9.1% of total U.S. medical expenditures in 1998 and may have reached as high as $78.5 billion, according to the CDC. Approximately half of these costs were paid by Medicaid and Medicare.

From big chains to mom-and-pop operations, pizza is about a $50 billion business in the U.S. Many pizza restaurants have suffered in recent years from wildly fluctuating commodities prices; meanwhile, cash-strapped have customers increasingly chosen to dine out in cheaper fast-food restaurants. An 18% tax increase on pizza and soda would be devastating to the industry, which counts on soda sales to boost its profits, says Jennifer Litz, editor of Pizza Marketplace, an industry Web site.

Some pizza chains seem puzzled as to why their product specifically is under fire from anti-obesity activists.

"Pizza is completely customizable -- you can make it as healthy or as indulgent as you want," says Tim McIntyre, vice president for communications at Domino's Pizza Inc. (DPZ), in an email statement. "It's the consumer's choice. Blaming certain foods [for] obesity is a stretch, to say the least."

At the very least, we should not make the cure for obesity worse than the disease.