Why Are Americans Getting Bigger? The National Bureau of Economic Research recently published a new paper about obesity rates and average BMI. NPR's Arun Rath talks with economist Charles Courtemanche, who worked on the study.
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Why Are Americans Getting Bigger?

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Why Are Americans Getting Bigger?

Why Are Americans Getting Bigger?

Why Are Americans Getting Bigger?

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The National Bureau of Economic Research recently published a new paper about obesity rates and average BMI. NPR's Arun Rath talks with economist Charles Courtemanche, who worked on the study.

ARUN RATH, HOST:

The Food and Drug Administration has approved the first electronic implant to fight obesity. It's called the Maestro Rechargeable System and uses electrodes to interfere with signals between the brain and the gut. Now, the results aren't dramatic - around a nine percent weight loss. The people who received a placebo device that did nothing had a six percent weight loss. But you can bet there'll be more devices that improve upon the Maestro because obesity is a serious problem that's not going anywhere.

According to the Centers for Disease Control and Prevention, since 1980 the nation's obesity rate among adults has doubled - for children, it tripled. And we're talking about everybody - men and women, rich and poor, all races and ethnicities, in every state. It seems like every day there's news of another study to explain our collective weight-gain.

(SOUNDBITE OF NEWS SEGMENT)

UNIDENTIFIED MAN #1: All new at 10 tonight, when it comes to having the most obese people...

UNIDENTIFIED WOMAN #1: A new study from Stanford...

UNIDENTIFIED MAN #2: Between the rise of Walmart and the rise of obesity...

UNIDENTIFIED MAN #3: The obesity rate...

UNIDENTIFIED WOMAN #2: The more obese an area is, the higher the unemployment rate.

UNIDENTIFIED MAN #4: Food stamps also make a significant...

UNIDENTIFIED WOMAN #3: High gas prices will reduce obesity.

RATH: But getting the big picture from a scientific study that looks at a single factor is like trying to take in a landscape through a soda straw.

Charles Courtemanche is an economist at Georgia State University. He says the problem with looking at all these studies individually is that the variables tend to be related. Economists are used to juggling multiple variables in their analyses. So Courtemanche and three other economists decided to look at 27 different factors, like concentration of restaurants, grocery stores and food prices.

CHARLES COURTEMANCHE: We also looked at on-the-job exercise, percentage of the workforce in a blue-collar as opposed to a, you know, white-collar service job. We looked at anti-smoking policies, food stamp spending, median income, unemployment rate, income inequality and work hours.

RATH: Courtemanche and his colleagues threw it all into a statistical model to see exactly how much each thing was affecting the average Body Mass Index and the obesity rate. They found that these 27 things all together accounted for about 37 percent of the rise in average BMI and 59 percent of the rise in severe obesity.

COURTEMANCHE: The two factors that really jumped to the top, that win the horse race - the first one is big-box grocers. So that's a Walmart Supercenters and warehouse clubs like Costco and Sam's Club. The other factor that jumps up is restaurants. So essentially, you know, the story here is cheaper and more readily available food.

RATH: Supercenters alone, they found, accounted for 24 percent of the rise in severe obesity. More restaurants meant a 23 percent increase - food stamps, 8 percent. Other factors had a much smaller effect. But those 27 things don't account for everything. What about the rest?

COURTEMANCHE: At this point you start getting into some things that are harder to measure. You know, in particular, I think it would be really helpful to be able to measure the effect of things like, you know, video games and computers and all of these sort of improved quality of sedentary activities and how that might make people substitute away from exercise and towards sedentary lifestyles.

RATH: Charles Courtemanche says there could also be some hard-to-explain cultural shift or even just some measurement issues with the variables. In other words, there's still quite a bit more work for economists.

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