Much has been written about the merits or demerits of Bloomberg's large soda ban (here was my recent take on it in the New York Daily News).
However, there has been much less actual research conducted to determine whether such restrictions might curb consumption or on how retailers might respond. Well, some researchers from UC San Diego conducted a small scale study on the issue that was just published in the journal PLoS One.
What they showed is that food companies can get around the ban by offering bundles of smaller-sized drinks and that people respond in kind by buying more soda! The study reminds me of what happened when San Francisco tried to ban giving away toys in Happy Meals; McDonalds decided to instead sell them for a very low price ($0.10).
That's the problem with a lot of these regulations - people and companies find a way around them in ways that the regulator couldn't envision and, as this PLos ONE study shows, it might even lead to weight gains. It's like squeezing a balloon - the air doesn't leave it just moves to a different place. Banning large soda or Happy Meal toys doesn't diminish demand for these items, it just causes people to seek out alternative means to get them.
Here is the study abstract:
We examined whether a sugary drink limit would still be effective if larger-sized drinks were converted into bundles of smaller-sized drinks.
In a behavioral simulation, participants were offered varying food and drink menus. One menu offered 16 oz, 24 oz, or 32 oz drinks for sale. A second menu offered 16 oz drinks, a bundle of two 12 oz drinks, or a bundle of two 16 oz drinks. A third menu offered only 16 oz drinks for sale. The method involved repeated elicitation of choices, and the instructions did not mention a limit on drink size.
Participants bought significantly more ounces of soda with bundles than with varying-sized drinks. Total business revenue was also higher when bundles rather than only small-sized drinks were sold.
Our research suggests that businesses have a strong incentive to offer bundles of soda when drink size is limited. Restricting larger-sized drinks may have the unintended consequence of increasing soda consumption rather than decreasing it.
While the study findings are intriguing, it must be said that the study is far from perfect. For example, the study involves a bunch of college students making a number of hypothetical choices. I'd much prefer to see an experiment where people actually had to pay (and eat) what they bought. Moreover, as the study authors readily acknowledge, the study doesn't reveal whether people would actually drink both sodas or just give one to a friend, nor did it differentiate between diet or full calorie soda. Thus, there appears to be fertile ground for additional research.