WASHINGTON — A day after New York City Mayor Michael Bloomberg's Health Department went to court to defend its proposed cap on the sale of super-sized sodas, a published study offered evidence that Bloomberg's plan would reduce average calorie intake among those most likely to buy large drinks, and would have its greatest effect on overweight and obese kids.
The study, conducted by researchers at Columbia University's Mailman School of Public Health, also found that low-income consumers were no more affected by a portion cap than were those of higher income -- a major challenge to opponents of the proposed cap, who have argued it unfairly targets the poor.
The research was published in the American Journal of Clinical Nutrition.
Among patrons of food-service establishments who would normally buy a sweetened soda in a container larger than 18 ounces, the researchers explored the effect of a variety of consumer responses to the portion ban, ranging from the wholly compliant to the completely defiant. In a scenario they suggested might be most realistic, the researchers presumed that 80 percent of consumers would respond to the portion-control measure by buying a 16-ounce drink instead. The remaining 20 percent would purchase two 16-ounce drinks, an end-run that would result in more calories consumed.
If such a cap were to extend across the country — an unlikely prospect — and 80 percent of consumers responded to it by buying smaller drinks, the researchers projected that each American child would reduce his or her daily caloric intake by an average of 6.9 calories, with an average 6.3-calorie daily reduction for every American man and woman.
Past research has established that overweight and obese Americans are more likely than normal-weight consumers to buy and consume super-sized sweetened drinks in food-service establishments. Consequently, the average daily calorie reduction among the overweight and obese — 4.8 calories for adults and children alike — would be greater than those among Americans of normal weight. Such adults would take in an average of 4.2 fewer calories daily, and children would take in on average 3.3 fewer calories daily.
University of North Carolina nutrition expert Barry Popkin said the study fulfills a needed bit of data to demonstrate that a portion cap on sugar-sweetened beverages would dial down Americans' calorie consumption. Behavioral economists have already shown in studies that, faced with limited serving sizes on sugar-sweetened beverages, consumers do not respond by doubling their order, but by paring back. The current study, which draws on a detailed federal database of Americans' dietary habits to probe the effect of a change in consumer behavior, adds a crucial next step to that data, Popkin said: It shows that consumers would take in fewer calories, and that the consumers who most need to reduce their calorie intake (the overweight and obese) will do so the most.
At the same time, the finding that low-income consumers pared about the same number of calories from their daily intake as those with higher incomes may undermine an argument mustered by many opponents of soda restrictions or taxes: that such measures restrict poor people's choices but not those of higher-income consumers.
Gus K. West, president of the Washington-based Hispanic Institute, says it's time for that argument to lose its power anyway. In low-income communities and Latino communities disproportionately affected by obesity and diabetes, measures that drive down sugar-sweetened beverage consumption should and will have a heavy impact — for the better, West says.
"We believe overall, the community as a whole is going to benefit more than be negatively affected. We don't believe they've demonstrated the store owners are going to really suffer any hardship, and there's no evidence to prove that low-income consumers are going to turn around and buy another portion. We don't buy that argument."