Obesity Top 10 – Caveat Lector!

Obesity top 10 lists — the fattest and leanest states — made for the latest set of headlines from the Gallup-Healthways Well Being Index this week. The supposed news here is that Mississippi has replaced West Virginia with the highest obesity rate, and that Montana has replaced Colorado with the lowest obesity rate.

For entertainment and PR value, all this coverage is a solid win for Gallup and for Healthways, a wellness company based in Tennessee. So far, they’ve gotten broad coverage through two cycles of headlines from high profile media. But the funny thing is that most of the coverage has been free of any critical thinking about the conclusions presented as definitive facts.

In the first round, the headlines were all about how obesity rates were ticking up. Now in this round we have the top 10 fattest and leanest states.

The weakness in these headlines is the data. All these obesity prevalence numbers are based on how tall and heavy people say they are in anonymous interviews. Such numbers have two big problems. First, people are always taller and lighter when they get to self-report. And second, the little fibs people tell about their height and weight are not uniform.

Researchers at the University of Alabama at Birmingham (UAB) have shown that people in different regions warp the picture by lying more or less about their height and weight. For example, they showed that people from states like Mississippi and Alabama are more accurate in reporting their height and weight than people from North Central states like Minnesota and the Dakotas. And these differences are enough to change the rankings. So comparisons based on self-reported data are inherently flawed.

Reader beware!

Click here to read the Washington Post’s unquestioning report of these flawed rankings. Click here to read more from ConscienHealth and here to read the UAB study published in the January issue of Obesity.

Asterisk in the Snow, photograph © theilr / flickr

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