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What Does Your Local Food Environment Say About Your Waistline?

Not much, according to a new study.
Farmers market in Dallas, Texas. (Photo: Allen Sheffield/Flickr)

Farmers market in Dallas, Texas. (Photo: Allen Sheffield/Flickr)

As many as 90 percent of Americans could one day be eating food produced within 100 miles of their homes, according to a recent farmland mapping project. What, we might wonder, would such a transition (given that, at most, 12 percent of our food is now locally sourced) accomplish?

The benefits that accrue to thoughtfully cultivated local food systems are well known: stronger communities, protected green space, fresher food, and better access to local farmers. These trends we could certainly expect to see.

But the relatively novel quest to take seriously the local food environment has led advocates to occasionally overstate claims. We’ve hence become aware that local food is not necessarily more sustainable, that localism easily becomes chauvinism, that factory farms continue to dominate agricultural production, and that local farms are not always as upstanding as we assume them to be. Like anything, eating local has its pros and cons.

If the impact of local food systems is complicated by an endless array of factors that we’re only now starting to appreciate (and ground in hard data), an article published in the journal Obesity has just made matters even more complicated.

Obesity rates have doubled in the United States since the 1980s. During this time, caloric intake has increased by 500 calories per adult per day.

It’s commonly assumed that a direct causal connection exists between the local food environment and obesity—that, for example, access to healthier food outlets will reduce obesity while a preponderance of fast-food joints will enhance it. But, as this literature review finds, this isn’t always the case. There is, the authors explain, “limited evidence for associations between local food environments and obesity”—limited enough to make “causal inference problematic.”

The most significant finding is that, across scores of studies, a majority of associations between the local food environment and obesity trends were null—no connection whatsoever. To put this fact in perspective, consider that the authors discovered a positive correlation between fast-food outlets and obesity in 29 studies, a negative correlation in six, and no correlation either way—null—in 71. Likewise, they found an inverse relationship between supermarkets and obesity in 22 cases, a positive relationship in four, and 67 null relationships. In the end, sometimes you get what you’d expect, sometimes you don’t, and sometimes you get the polar opposite.

It’s worth highlighting the wisdom of looking at these studies in the collective. The media typically reports on a single study taken out of its larger research context. Typically, the studies that get attention, and then go viral, are those that document a causal impact. A positive correlation is more newsworthy than a null one, even if the majority of the unreported studies are null. This tendency creates a serious bias and, as the obesity meta-analysis suggests, it can confuse our thoughts about the deeper causes of obesity.

And right now the stakes are too high to sow confusion over this matter. Obesity rates have doubled in the United States since the 1980s. During this time, caloric intake has increased by 500 calories per adult per day, according to the Centers for Disease Control and Prevention. The health consequences of this binge have been catastrophic; it seems there’s no end in sight to the nation’s expanding waistline.

The authors of the Obesity article are by no means suggesting that local food environments don’t matter when it comes to fighting obesity. Cheryl Anderson, an associate professor of family medicine and public health at University of California-San Diego and one of the study’s authors, told me that “personal choice can be hindered when individuals do not have access to healthful options where they live.”

But their findings indicate that, among other possibilities, there’s no single, isolated factor within the local food environment that accounts for obesity trends. “Our sense,” the authors write, “is that given the many potential causes of obesity, the impact of any individual cause including the local food environment is likely to be small.”

“There are multiple factors that influence obesity—interventions will have to be multifactorial,” Anderson added.

This discovery, if nothing else, gives us permission to be more creative in our thinking about obesity. My own sense is that, as concerned consumers and policymakers, we’re too easily (if understandably) attracted to the idea that we can engineer the physical environment to ameliorate the problem. Because building food systems in which 90 percent of us could, say, eat locally sourced food would be the simplest (or at least the most tangible) solution, we’ve glommed onto it with great enthusiasm. (A 2009 Alternet headline: “MIT: Eating Local Food Is the Key to Solving Our Obesity Epidemic.”)

But what if deeper, more finely grained psychological factors are at work (as they almost certainly are)? What if the root causes of our dietary decisions come not from what’s around us but from what’s happening inside of us? What if the problem of overeating has more to do with our internal, emotional environment than the external, built one? What if we create ideal foodsheds only to have those prone to obesity drive past the farmers’ markets to the fast-food outlets?

If this recent study is correct, if the connection between the food environment and obesity isn’t as we once thought, then these are the questions—the far more difficult questions—that we’ll need to start pondering.

The Things We Eat is a regular Pacific Standard column from James McWilliams on food, agriculture, and the American diet.