Sugar-sweetened beverages such as regular soda have become the focus of intense debate in the US as public health advocates and policy makers argue that these drinks are driving the obesity epidemic, which is, in turn, driving huge health care costs. The answer, many argue, is to start thinking of soda in the same terms as tobacco, and subject it to a sin tax.

Proponents of a soda tax argue that it would curb consumption and, therefore, reduce obesity and its related illnesses. A tax would also provide significant revenue for cash-strapped states, some of which could be used to offset health care costs. The scale of this problem, they argue, justifies government interference.

Opponents of soda taxes argue that the supposed benefits are illusory, the economic modeling flawed, and the interference in personal liberty is too great and too arbitrary. The sugar in soda should not be seen as the equivalent to the chemicals in cigarette smoke, they argue, otherwise fruit would be as harmful as soda. A calorie is a calorie, no matter where it comes from.

This debate can be seen as a clash between competing philosophies over the right balance between personal liberty and government intervention. But it is also, fundamentally, a debate driven by data: How strong is the relationship between drinking soda and gaining weight, and how good are the models that predict a soda tax would reduce obesity? It’s only by looking at how a social problem is modeled and how those models relate to empirical evidence that we can assess whether a solution is likely or unlikely to work.

The following analysis looks at each element of this argument and asks whether the data adds up to a compelling case for either position. It also looks at whether the media has provided the public with the relevant information it needs to reach an informed decision on this issue.


Writer: Trevor Butterworth
Editor: Rebecca Goldin, Ph.D
Last Updated: 21/12/2011
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New studies on dynamics of energy balance gut soda tax goals
The case for taxing sugar-sweetened drinks to curb obesity, which is being enthusiastically advanced by some of the most prominent public health experts, wildly overestimates weight loss, according to two new studies.






sodatopFat that fizzes or analyses that fizzle?

The premise behind taxing soda is simple: We shouldn’t be drinking so much of it. But what does the current state of the science tell us about the impact of drinking sugar sweetened drinks on weight?


Has increased soda consumption driven the increase in weight gain and obesity?
One might think that the link between drinking sugared beverages and gaining weight is beyond the need for confirmation, but that if one wanted such confirmation, the evidence would be abundant and robust. Surprisingly, this is not the case.


sodatopWhen good intentions lead to bias in obesity research.
The less rigorous the study, the greater the association it found between soda and weight gain, and the more likely it was to be published.


sodatopA “disappointing” lack of good research
One thing most researchers agree on, the research on soda and weight gain is poor and full of methodological problems - and there's a need for high quality radomized control trials.


sodatopWill a tax on soda reduce consumption and lead to a reduction in weight and obesity?
Despite the “disappointing” quality of the evidence linking soda to weight gain, proponents of soda taxes tend towards selectively citing the strongest studies when arguing for implementation.


sodatopHow do current soda taxes work?
There are, presently, 33 states that implement some form of soda taxation. Have they had an effect on consumption? What do soda tax proposals hope to achieve?


sodatopThe problem with modeling sodal taxes: price elasticity
It's not quite as simple as "if we raise the price, people will cut back or switch to something that has lower calories."


sodatopHow has the media framed the issue?
Soda taxes have been a hot topic in the media for the past three years, but as one study shows, the media was only interested in one expert perspective, that of tax advocates.


The determination to solve a public health problem of crisis proportions is to be applauded and encouraged; but the determination to solve a public health crisis by any means necessary can bend enthusiasm toward plausible yet unproven solutions.