Photo of the day

Recent National Geographic photo of the day:

Photo: Renan Ozturk slacklining over the Gavea Stone in Rio de Janeiro

Slackline, Rio de Janeiro

Photograph by Tim Kemple

This Month in Photo of the Day: Adventure and Exploration Photos

The sunset slackline image is of my good friend Renan Ozturk slacklining over the Gavea Stone in Rio de Janeiro, Brazil.


Correlation, causation, and food deserts

Nice long post by Sarah Kliff in Wonkbook about existing research on food deserts (areas without easy access to healthy food) and Philadelphia’s attempt to eradicate them.  Despite all you might have heard of food deserts in poor communities, there’s actually no evidence that they in any way cause obesity, rather:

a growing body of research has questioned its basic assumption: that people will eat better if given better options. Multiple studies have scoured local, state and national data looking for a causal relationship between weight and access to healthy food. None has found it…

Public health researchers have long known that lower socioeconomic status correlates with worse health, including higher levels of obesity. Numerous studies have also noted connections between access to healthy foods and lower weight. A 2011 article in the Journal Obesity Review found that “greater accessibility to supermarkets or less access to takeaway outlets were associated with a lower prevalence of obesity.”

If governments could improve proximity to healthy foods, the theory went, it could reduce a rapidly rising obesity rate.

Kliff points out that the theory has not been able to be particularly well tested, but insofar as it has, there’s not been any evidence for a causal relationship.    Poor communities having higher rates of obesity for many reasons and they fewer supermarkets and more take-out outlets.  But there’s no reason to believe these factors are causing the obesity– this may be a perfect example of a spurious correlation.

Wrigley conducted one of the first studies of a food desert intervention, looking at what happened when a grocery store was brought into an underserved part of Leeds, an industrial city in northern England. Of shoppers surveyed, 45 percent switched to the new store. Their habits, however, barely changed: Consumption of fruits and vegetables increased by one-third of a cup per day — about six grapes or two broccoli florets.

“The results came out quite small, a very modest increase in consumption of nutritious foods,” Wrigley says. “It seemed an almost nonexistent improvement.”

Similar research in the United States shows much the same.

The amount of healthy food I personally have had in my diet has varied tremendously over the years and I’m pretty damn sure (yes, I know I am an N of 1) that access had absolutely nothing to do with it.  Also, you want a “cheap” food”  Bananas are an absolute steal!  I cannot believe how cheap they are.  And a bag of Gala apples is amazingly affordable, too.  People aren’t choosing to not buy these foods over price issues.

I’ve become persuaded that the government really should play a role in combating obesity.  I’m just skeptical of whether attempts to eliminate food deserts will do much on that score.  But, hey, as a good liberal, I’m open to evidence.  If the Philadelphia experiment works– great; if not, we’ll know that we need other approaches.

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