Will Soda Taxes and Fast-Food Bans Fix Obesity?

Last week in San Francisco, the city council voted to ban including toys with fast food that doesn't meet a certain nutritional standard (San Francisco's mayor plans to veto the ban, but he'll also have to appeal to the council, which has enough votes to override the veto). In New York, the public-health commissioner is pushing to forbid using food stamps to purchase sodas and other sugary drinks. In Portland, Maine, restaurants will now have to list the calorie content of all their menu items.

These policies—and others like them throughout the country—are imposed with the best of intentions: designed to improve wellness, reduce health-care premiums, and help citizens lose weight and eat healthfully. But do they work? The answer, for now at least, is "who knows?" The truth is, while government agencies—as well as businesses and private institutions—are all looking for ways to battle the obesity crisis, no one has yet figured out successful interventions that both improve health and save money. Programs that are being implemented are often unproven and untested.

The ad-hoc, grassroots nature of these programs makes them hard to track, and it's difficult to evaluate their success rates or determine whether what works in Peoria would play well in Pensacola. "Thinking about healthy eating and access to physical activities is a community issue, so communities are looking to address it in a lot of different ways," says Aviva Must, chair of the public health department at Tufts University. In the case of obesity, she argues, that type of creativity should be encouraged. "We're going to want to try to design studies to collect evidence to understand which approaches are most effective, but I don't think we can sit back and wait for these perfect studies to tell us that a, b, and c are good, and d, e, and f are less effective."

Once plans are in place, it can be difficult to assess how cost-efficient and successful they are. "People find it very threatening, the idea that you might come along and say "it didn't do anything." I think sometimes the people in the trenches feel like, why are you hassling me, I'm very well intentioned, aren't there other things you should be doing with your time?" says John Cawley, an associate professor of policy analysis and management at Cornell University.

While there is some published research on the effectiveness of these plans, the findings are contradictory. Studies show that increased costs discourage consumption of unhealthful food, but that soda taxes don't reduce beverage consumption. Listing calorie totals on menus leads to consumption of 250 fewer calories per meal in a controlled study, but no real difference at Starbucks in California. While some of these programs are based around successful interventions in other areas—taxes on cigarettes, or restrictions on WIC food-subsidy programs—there are too many subtle shifts and big variables to draw any real parallels. And many of these initiatives—for instance, the Happy Meal laws—are being enacted for the first time, with no real precedent to guide them.

That public-health officials don't know how to tackle the obesity crisis is due in part to the fact that researchers are still unsure what's causing it (if obesity is the cause of chronic diseases in the first place). Rising obesity rates have been linked to race and sleep, going on food stamps, viruses, pollutants, and bacteria; but what's causal, what's correlation, and what's just a coincidence is still not understood.

As such, these public-health plans are often based on best guesses given available evidence, not the result of rigorous scientific calculation. "If you think about the study designs, it's very difficult, and there's a lot of background noise," says Must. "We're going to have to rely on our good sense and to understand if you can create an economic environment that has disincentives for eating unhealthy foods, that it will drive people to more healthy choices." Even things as basic as the government's dietary guidelines—the food pyramid—are more opinion than fact. "The guidelines that are promulgated are based on reasonable science and inference from observation, but evidence to support the effectiveness of the guideline is not there," says Paul Marantz, the associate dean for clinical research education at the Einstein College of Medicine at Yeshiva University. Similarly, "we have reason to believe that exercise is in general a good thing, or conversely that sedentariness is not a good thing, but we don't know whether telling people we should exercise three times a day, three times a week, achieves an improvement in health." (Witness how often those guidelines have changed).

In most cases, a little experimentation in the name of public health is a good thing, says Cawley, as long as the stakes are low—building public sidewalks is a costly project that would require a lot of evidence of efficacy before it's implemented, he argued. "As an economist, I'm much more willing to experiment with a policy when there's no apparent downside—it may end up being ineffective, but there's no down side to the government or doesn't harm anyone."

That's the problem, says Marantz. "There's the potential for harm that's often underrecognized," he notes. For instance, he argues, dietary regulations that pushed carbohydrates over fat in the 1980s and '90s was based on the spurious assumption that high-fat diets lead to heart disease, As a result, people ate more carbs, consumed more calories, and gained more weight (the argument is a hot topic in the nutrition community). Marantz encourages communities to keep tabs on the effects—both intended and otherwise—that result from public-health initiatives. But he also recognizes that long-term, rigorous testing is unrealistic in a climate where everyone is clamoring for a solution to chronic illness. "That's what makes this area really neat—it's the Wild West," says Cawley. "Every level of society is trying something."