Science, Sensation, and Politics in Obesity Numbers

Childhood obesity numbers caused quite a stir when science, sensation, and politics collided very publicly last month. The result has been considerable confusion about childhood obesity trends and concern about injecting politics into the science of epidemiology.

In late February, CDC epidemiologists produced a very solid report in the Journal of the American Medical Association that stated “there have been no significant changes in obesity prevalence in youth or adults between 2003-2004 and 2011-2012.” But the CDC press release on this report highlighted numbers from children two to five years old. The numbers showed an impressive 43% decrease that was probably a statistical fluke, but it made its way into headlines.

With the benefit of time to reflect upon this fiasco, two observations rise to the top.

  1. The CDC press release was a mistake. By highlighting a questionable statistic that happened to tell an expedient story, CDC has created confusion and undermined its credibility needlessly. Holding the public’s attention for important health issues is hard. Mixed messages and false suggestions of “mission accomplished” make it harder.
  2. Preschoolers might indeed show improvements first. Bill Dietz recently pointed out that this age group would require significantly smaller changes in calories to have an impact on obesity rates. Quoting an analysis by Claire Wang, Dietz pointed out that a change of 33 calories per day would be sufficient for an impact in children two to five years old. Older children would would require changes of 150 calories per day or more. And changes like adjustments to the WIC program might well be pushing things in the right direction. But he was quick to point out that the claims of a 43% reduction in this age group were a mistake. The data to back them up are not in hand.

Credibility is tough to earn and easy to squander.

Click here and here to read more about problems with claims of a 43% drop in preschool obesity. Click here to read the analysis by Wang et al.

Science Buzz, photograph © Nic McPhee / flickr

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