The Fatal Flaw in Bloomberg's Soda Ban

When New York City mayor Michael Bloomberg announced last week that the city's Board of Health of health would ban selling sodas and other sugary drinks over 16 oz., the public mostly reacted as though Bloomberg had gone one step too far down the slippery slope of nannyism and fallen right off the cliff.

If his previous intrusive public health measures – the trans fat restrictions, smoking crackdown, and calorie posting mandate – were paternalistic nudges, the proposed soft drink ban represented a shove that most people weren't prepared to take. The soda ban seems petty and thus absurd, as if New York faces so few problems that the mayor can bother himself with teenagers sipping Big Gulps on its sidewalks (although Big Gulps, it turns out, would escape the ban).

Yet Bloomberg is right that obesity is a problem, both in NYC and nationally, that demands a governmental response. The problem he faces is that the only policy levers he has access to are the wrong ones.

The policy changes that would most discourage obesity would take place at the federal level. Ending corn subsidies would be one. Because of the host of incentives the government offers farmers to grow corn instead of other crops, high-fructose corn syrup is prevalent in the U.S. In fact, the sugary soft drinks Bloomberg is so worried about are almost exclusively sweetened with high-fructose corn syrup, which is probably even worse for your health than sugar. It's been estimated that, of the run-up in sweetener consumption since 1970, fully 65 percent is accounted for by high-fructose corn syrup in sodas.

Corn's role in worsening obesity goes beyond soda, though. Many of the most fattening, unhealthy foods available are an indirect product of artificially low corn prices. It's not likely that a double cheeseburger (made from corn-fed beef) would be economical for a fast-food restaurant to sell for a dollar if it weren't benefiting from corn subsidies.

Corn subsidies are by no means the only government policy that makes us fat (school lunches also come to mind). But they probably outweigh any anti-obesity campaign a city mayor can realistically devise.

Bloomberg, however, has no control over what the federal government subsidizes. If his administration thinks that counteracting the variety of policies that promote obesity is a legitimate goal for New York's government, than he's forced to try to regulate unhealthy food at the city level or alter consumers' behavior. Making it harder to sell high-calorie foods and drinks within city limits might be the only way.

The Big Gulp ban may be the best option available to Bloomberg, but it's probably not a good one. The motivation for the ban on large size sodas is that a number of studies suggest that people tend to overeat when given large portions. Even though New Yorkers would still have access to as much soda as they want at any given time (in smaller cups) under ban, the hope is that smaller servings will nudge them away from overconsuming.

Clever, but a bit too simple. Obesity is a complicated phenomenon; surely there's more to it than ever-expanding portions.

In a 2003 study, the economists David Cutler (a former health care advisor to President Obama), Edward Glaeser, and Jesse Shapiro examined the causes of rising obesity in the U.S. By investigating trends in Americans' caloric intake and time use, they reached a few surprising conclusions. Snacks account for the vast majority of the increase over the past 40 years in calories Americans eat each day. The authors also specifically rule out the possibility that increased portion sizes at restaurants are responsible. Instead, they present compelling evidence that technological advances that cut the time of food preparation are to blame.

French fries are a perfect example of Cutler et al.'s thesis: fifty years ago, people ate potatoes frequently and in large quantities. However, they would generally eat them baked or mashed. Today, with mass production and deep freezing, the majority of potatoes are eaten as French fries, either deep-fried at restaurants or microwaved or baked at home. Cutting fries by hand and frying them oneself would be too time-consuming to be practical back in the day, but nowadays fries – the fattiest form of potatoes –  are available for cheap, and for hardly any labor. That formerly labor-intense foods are now available as snacks is behind the obesity epidemic.

Although Cutler et al.'s study relates to food, the logic is the same for soft drinks. The problem isn't the size of the drinks, it's that they are available with minimum effort.

Short of banning microwaves and freezers, it's not clear what Bloomberg could do to reverse the situation. Making people buy smaller drinks at theaters and hot dog stands won't do it. Perhaps a broad-based, steep tax on all sodas could make a difference in Gothamites' behavior, as it would influence every decision to drink such large quantities of sugar. But the bottom line, as he is finding out right now, is that there just aren't many attractive options available to a mayor.