Evidence for Action in Obesity

Questions about the evidence for action to reduce the impact of obesity were at the center of a thoughtful and lively advocacy forum yesterday at ObesityWeek 2014. Moderated by ConscienHealth’s Ted Kyle, presenters examined the problem of taking action when the evidence for the potential effects of action is incomplete.

Bill Dietz — who led CDC efforts against obesity for many years — opened the forum by examining how the evidence of a role for sugary drinks in obesity has evolved all the while that actions to address it have been vigorously debated. Joe Nadglowski, CEO of the Obesity Action Coalition, explained that even though policymakers are often well-informed about the science, it is far from being the primary factor that drives decision-making.

Dennis Bier, Editor of the American Journal of Clinical Nutrition, shined a light on the wide variation in standards for an acceptable level of evidence. From one paper, he quoted the authors asserting that observational “prospective cohort studies are regarded virtually on par with RCTs [randomized controlled trials],” while in the same paper, the authors said:

You should discount all claims about effects discovered in observational studies. Consider them hypotheses to be evaluated.

Finally, Bruce Wolfe presented information provided by bioethicist Leonard Glantz of Boston University, reminding us that people hold sharply different views of obesity that are commonly expressed as bias and discrimination. The implication is that actions lacking a strong foundation in the evidence have potential to do substantial harm.

The panel discussion, with a long line of questions from the audience brought differing views about the sufficiency of evidence for policy actions. On one hand, Dietz drew parallels to actions against tobacco and smoking despite a lack of RCT data. On the other, Bier pointed out that the magnitude of the suggested effect size for sugary drinks is much smaller than was evident for smoking and tobacco.

The one point of agreement was on the corrosive effect of bias in decision making. Kyle closed the session by saying:

Pervasive biases about obesity and people with obesity has the effect of sometimes constraining scientific curiosity about this disease. That constraint limits our options.

Click here for more about policy sessions worth noting at ObesityWeek 2014.

Action? Photograph © Jay Melnick / flickr

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