The Centers for Disease Control and Prevention (CDC) has admitted that its report blaming obesity for 400,000 deaths a year has serious problems. As the Los Angeles Times reports today: “A controversial government study that may have sharply overstated America’s death toll from obesity was inappropriately released as a result of miscommunication, bureaucratic snafus and acquiescence from dissenting scientists.” The CDC’s admission comes
seven months after the Center for Consumer Freedom first called into question the 400,000 deaths figure.

The controversy actually began well before JAMA published the CDC’s 400,000 deaths estimate in March of 2004. At that point, some of the CDC’s own scientists had already submitted for publication studies concluding that the agency’s methodology for calculating obesity-related deaths significantly exaggerated the problem. In May, Science magazine reported that some CDC researchers felt political pressure to remain silent about problems with the 400,000 figure:

Some researchers, including a few at the CDC, dismiss this prediction, saying the underlying data are weak. They argue that the paper’s compatibility with a new antiobesity theme in government public health pronouncements — rather than sound analysis — propelled it into print.

The CDC has now acknowledged some of these criticisms. The recent report from a CDC review committee (which can be found here, buried on the agency’s website) notes:

The scientists expressed concerns and did meet with some of the authors but they were not convinced that their perspectives were listened to or that requests for data were acknowledged.

The review committee report also acknowledges serious methodological problems with how it calculated obesity-related deaths:

The paper published by Mokdad, et al., Actual causes of death in the United States 2000, has provoked significant controversy both inside and outside the agency. While there was at least one error in the calculations and both the presentation of the paper and limitations of the approach could have been expressed more clearly, the fundamental scientific problem centers around the limitations in both the data and the methodology in this area.

This paragraph is especially important because it apparently contradicts a correction the CDC published in JAMA just last month. That correction admitted to the mathematical error referred to above, but then reaffirmed the underlying — and now discredited — methodology. The independent review committee urged “more sophisticated approaches,” and noted “there had been some criticism of the approach used by Allison in the literature.”

Here the committee is referring to a paper by financially conflicted obesity researcher David Allison, which the CDC relied on to calculate obesity-related deaths. As we’ve explained many times before (click here, here, here, here, and here), Allison’s study presents a host of methodological problems that all serve to exaggerate the risk of obesity.