People buy larger amounts of soda when purchasing packs of smaller drinks than when offered single servings of different sized drinks, according to research published April 10 in the open access journal PLOS ONE by Brent M. Wilson and colleagues from the University of California, San Diego.
The researchers tested the effects of limiting sugary drink sizes on people's soda consumption by offering them three kinds of menus. One menu offered 16 , 24 or 32 ounce sized individual drinks, a second gave them the choices of a 16 oz. drink, or bundles of two 12 ounce drinks or two 16 ounce drinks, and a third menu offered only individual 16 oz. drinks for sale. When participants made choices from these menus as they would in a fast food restaurant, people bought more soda from the menu with packs of 12 oz. or 16 oz. drinks than they did when offered individual sodas of different sizes. Based on the choices participants made, total business revenues were also higher when menus included packs of drinks rather than only small sized drinks.
The study concludes that when drink sizes are limited, businesses may have a strong incentive to offer packs of several small drinks rather than only individual servings. The authors suggest that restricting larger servings of sugary drinks in efforts to moderate may thus have the unintended outcome of increasing soda consumption rather than reducing it.
"Our research shows the New York City ban on large-sized drinks may have unintended consequences that policy makers need to consider. Sugary drinks are a major source of business revenue, and businesses will adjust their menus in order to maximize profits," says Wilson.
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Wilson BM, Stolarz-Fantino S, Fantino E (2013) Regulating the Way to Obesity: Unintended Consequences of Limiting Sugary Drink Sizes. PLOS ONE 8(4): e61081. doi:10.1371/journal.pone.0061081