We’ve said many times over in Sip & Savor that the body of science fails to prove that taxing soda will reduce waistlines. Similarly, when Mayor Bloomberg announced a proposed ban on sodas larger than 16 ounces – in the name of reducing obesity in the city of New York – like  two-thirds of Americans, we shook our heads and said, it won’t work.

Bloomberg claimed that science was on his side, when he made headlines around the world with the onerous ban. Portion sizes, he declared, are too big, forcing people to consume more than they would if only they had a smaller cup. Therefore, if people are limited in the size of soda they can order – and forced to think about asking for a second serving – they will reduce consumption.

There’s only one problem. The scientists Bloomberg cited in the portion vs. consumption research say the mayor misread their data. In fact, they’ve come out publicly in an article on TheAtlantic.com to warn that Bloomberg’s soda ban will backfire:

“We fear, however, that the proposed ban will be a huge setback to fighting obesity for two reasons: 1) unless it succeeds, it will poison the water for better solutions, and 2) it won't succeed.”

The researchers cite 150 years of research in food economics, which shows that people get what they want. If a consumer wants more than 16 ounces of soda, that person will find a way to get more than 16 ounces of soda. Bloomberg argues that if people are given smaller portions, they’ll consume less. Not according to the research:

“The mayor's approach, however, overtly denies people portions they are used to be able to get whenever they want them. In similar lab settings, this kind of approach has inspired various forms of rebellion among study participants. For example, openly serving someone lowfat or reduced-calorie meals tends to lead to increased fat or calorie consumption over the whole day. People reason that because they were forced to be good for one meal, they can splurge on snacks and desserts at later meals.”

The New York City soda ban is bad public policy, based on the preferences of politicians, not actual science. Just ask the scientists.