Pop Science: The Case for and Against the Soda Ban

March 12, 2013— -- Mayor Michael Bloomberg says "the best science" is behind his controversial ban on large-sized sugar-sweetened beverages, which was overturned by a lower court earlier this week, but that doesn't mean all scientists agree.

"The best science tells us that sugary drinks are a leading cause of obesity," Bloomberg said Monday during a press conference to criticize the court's ruling.

New York Supreme Court Judge Milton Tingling took issue with Bloomberg's rationale, saying in part that lack of science was one reason for overturning the ban.

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"The Board of Health may supervise and regulate the food supply of the city when it affects public health," and can do so when the city "is facing imminent danger due to disease," but that was not proven in this case, Tingling said in his written judgment.

So is the science on Bloomberg's side or not?

Sugary drinks are the single biggest source of calories in the American diet, providing more than 7 percent of daily calories on average, according to the Center for Science in the Public Interest. Statistics show both consumption of sweetened beverages and obesity rates have doubled since the 1970s.

Bloomberg's office released data Monday showing nine of the top 10 neighborhoods with the highest obesity rates city-wide were also the highest in sugary drink consumption. At the other end, the three least obese neighborhoods were also the lowest in sugary drink consumption.

While soda consumption has risen in lock step with an increase in the nation's collective waistline, that doesn't necessarily prove they are related, but an investigation published Monday in the American Journal of Preventive Medicine added to mounting evidence that they might be.

In the study of more than 10,000 children, researchers at the University of North Carolina in Chapel Hill found that sugar-sweetened beverages are the prime culprit responsible for higher caloric intake of children who consume them and are also associated with a higher intake of unhealthy foods.

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"This is concerning because many foods that are associated with higher sugar-sweetened beverage consumption -- pizza, cakes/cookies/pies, fried potatoes, and sweets -- are also top sources of solid fats and added sugars," said lead investigator Kevin Mathias, a professor with the University's Department of Nutrition.

The science also indicates that size matters.

Besides the obvious fact that bigger sodas deliver a greater number of calories, studies show people tend to underestimate the amount of calories they've eaten and eat more when served heftier portions.

"The data clearly shows people who are given large portions consume more without realizing it and if you shrink portions they consume less but still feel satisfied," said Kelly Brownell, a professor of psychology and epidemiology at the department of health at Yale University.

As Brownell explained it, liquid calories in particular don't register with the brain in the same way calories from foods do, so people who drink copious amounts of sweet liquids take in a greater number of calories without feeling full.

In shrinking soda servings down from the current default container size of 20 ounces to a more "human sized" 16 ounces, Brownell said he thought most consumers would still feel satisfied even though they would wind up drinking less.