Research Debate: Can a Soda Tax Make America Skinny?

THE DEBATE

SIDE 1: Yes, a soda tax will fight obesity!

Those who support the soda tax believe it would discourage people from downing sugary drinks and quell the rising tide of obesity.

Several studies suggest they’re right.

A 2010 study in the Archives of Internal Medicine followed 5,000 young adults over a period of 20 years and found that those who purchased a soda costing one dollar more ate 124 fewer calories that day. They concluded that an 18 percent increase in the price of soda could amount to a five-pound weight loss per person. Across the whole country, that could be substantial.

"Sugared beverages exact a toll on the nation's health and much like tobacco taxes have had a very positive impact, soda taxes could make a real difference for both adults and children," says Brownell.

A soda tax may even be more effective than subsidies on health food.

Researchers at the University of Buffalo found that a 10 percent tax on junk food—including sugary drinks—encourages women to purchase healthier, lower calorie foods at the grocery store, and is more effective than lowering the cost of health foods. In fact, cheaper health food actually encouraged women to “treat” themselves to junk food, leaving more calories and fewer nutrients in their virtual shopping carts.   

The most widely cited case for a soda tax is a 2009 article in the New England Journal of Medicine, written by Brownell and Thomas Frieden, director of the Centers for Disease Control and Prevention. They argue that the impact of a soda tax depends on how it is implemented, noting, “only heftier taxes will significantly reduce consumption.”

MORE: How Sugar Sneaks Into Your Diet

SIDE 2: No way, it’ll barely make a difference.

The nay-saying experts think a soda tax is unlikely to change behavior and won’t lead to noticeable weight loss.

Eric Finkelstein, associate research professor of economics at Duke University, does agree that a tax would help reduce consumption, but he doesn’t think that’ll lead to weight loss. “The problem is that any savings in calories is partly offset by switching to other beverages and to some extent, other foods. So this alone would have almost no effect on obesity.”

Some studies so far have supported that concern, including a 2010 study from Yale University, which found that soda taxes do impact BMI, but the effect is very small—much smaller than it would need to be to really combat obesity.

But all of that might be beside the point.

A 2011 study from Northwestern University, led by economics graduate student Ketan Patel, found that a tax on sugary drinks would miss the target: Obese people are much more likely to drink dietsoda. Not only that, but Patel found that obese people, regardless of socioeconomic status, are less price sensitive, meaning that a tax is unlikely to dissuade them from choosing the drinks they love.

MORE: Should There Be a Diet Soda Tax?

What’s more, tax or not, soda may still remain the cheapest beverage option. “Even with a large tax, soda is still cheaper than healthier drinks, so that is why [a soda tax] may be least likely to change behavior,” says Finkelstein. He’d rather see a tax on junk foods across the board, including French fries, potato chips, and other treats that are known to pad a paunch.