Too Fat to Fight

In several recent articles, the New York Times has revived the debate around “food deserts” and, in suggesting that they are not as pervasive a problem as once thought, stirred up controversy in food policy circles.  Whether the Times is accurate in its suggestion that food deserts are not a major contributor to the lack of proper nutrition in the United States, the debate serves as a salient reminder that fighting the epidemic of obesity is a complex task and not one that lends itself to easy bromides like “increasing access.”

That obesity and lack of nutrition are an enormous problem in the United States should not be open to debate.  Over 30% of American children are overweight or obese.  Unfortunately the problem is exacerbated by existing socio-economic and racial inequality; more than 40% of African-American and Hispanic children are classified as overweight or obese.  Obesity and malnutrition translate into increased health care costs for the country as a whole.  The effects go beyond higher healthcare costs.  Obesity is the number one reason why young Americans are turned away from military service today.  As food writer Mark Winne has suggested, world peace is a laudable goal but being “too fat to fight is perhaps not the best way to achieve it.

The inequitable distribution of obesity cases – with so many focused in urban, low-income environments – led to a focus on the notion of food deserts as a prime cause in the rise of obesity.  A food desert is defined as a census tract containing low-income populations, a third of which live more than a mile from a supermarket or a grocery store.  The definition provides a powerful intuitive reason to believe that food deserts are a primary cause of obesity; if low-income families cannot access high quality, nutritious food at a supermarket, it is not surprising there exist high-levels of obesity in these neighborhoods (implicit here is the view that the corner shops that take the place of supermarkets do not offer the same level of food quality – a fact often born out by reality).  It follows then that to solve the problem of obesity, one must provide access to high quality food by opening farmers markets, vegetable carts, and supermarkets in these low-income communities.

Unfortunately, the reality of what causes obesity is much more complex than a simple narrative of food deserts.  Several recent studies have shown that access to supermarkets and nutritious food does not have the desirable effects on obesity rates that it was assumed they would (subs. Req’d).  Not only that, but the presence of food deserts may have been dramatically over-estimated.  By some accounts low-income areas have higher access to large grocery stores than high-income areas and differences in access only weakly explain changes in Body Mass Index (BMI).  Looking at the evidence, a U.S. food policy expert has estimated that only 2-6% of Americans lack good access to a supermarket.  If that it is the case, food deserts are clearly not sufficient explanation for the obesity epidemic.

The majority of people fighting to fix food policy in this country are not surprised that food deserts are insufficient to explain the entire obesity epidemic in the U.S.  As one of the original coiners of the term ‘food desert’ points out, no reputable agency or individual in the food arena believes it was only an issue of access.  In Michelle Obama’s Let’s Move Campaign to end childhood obesity, fighting food deserts is only one of a five pillar approach.  The other pillars include providing healthy food in schools, increasing exercise, and educating about nutrition.

In a larger sense solving the obesity epidemic requires changes in policy to shift the incentive structure of American food production.  The subsidization of starchy foods means that on a dollars per calorie count, vegetables are some of the most expensive food you can buy and therefore out of the reach of many even if they can get to stores that stock the produce.  It requires cultural and policy shifts that make cities and towns more walkable.  Today, distances beyond 110 of a mile are beyond walkable for American children but the average American child spends 7.5 hours in front of TV/computers/video games.  Finally, addressing inequality may also directly help to fight the obesity epidemic by reducing the attractiveness of fast food.

The new controversy over food deserts is mostly a manufactured one.  The media latched onto the simple notion that access could explain the rise in obesity in American cities.  When it, unsurprisingly, failed to be the whole story – or even a majority of the story – they decried food deserts as an unnecessary and overwrought concern.  This simplistic narrative does nothing to solve the real problem.  Food deserts are not the only cause of obesity in the United States.  Lack of access to quality food is a significant problem but it is not the only problem.  Indeed, even access to a supermarket does not guarantee access to quality food.  It is time that the media took up the cause of nutrition and food policy in a serious manner.  By raising awareness of the complex nature of this problem they can put pressure on Washington and local governments to provide serious solutions.

Authors
  • Jacob AG

    “It requires cultural and policy shifts that make cities and towns more walkable.”

    Doesn’t this suffer from the same “simple notion that access could explain the rise in obesity” problem as the idea of filling food deserts with grocery stores? If having access to a supermarket doesn’t necessarily make a population less obese, maybe having access to a more walkable city doesn’t make a population less obese either.

    And does walking actually does reduce obesity? Is there (causal) evidence of this? Exactly how much weight does walking a mile lose? Gary Taubes (at al) have suggested that exercise isn’t the solution it’s cracked up to be, any more than filling food deserts is. His argument is that increased exercise causes increased appetite, so that burning more calories will lead to an increased consumption of roughly the same number of calories. Exercise, he suggests, isn’t as efficient a way to combat obesity as tinkering with insulin levels by eating fewer carbohydrates, more fat, and more protein. He cites credible studies (multiple, large-sample, randomized, clinical trials) that link fat/protein consumption causally and reduced carbohydrate intake to reduced obesity and related health problems… causally. And he has the biological mechanisms worked out too.

    • Patrick Behrer

      I don’t mean to suggest that walking will solve obesity by itself, or that filling food deserts is not part of the solution. Rather, they are each an element of a multi-part solution. As is, almost certainly, diet modifications of the nature that Gary Taubes suggests.

      His suggestion that increased exercise causes increased appetite true but that does not mean, automatically, an increased consumption of calories. If caloric consumption necessarily increased exercise would never lead to weight loss, which it clearly does in some (many) cases.

      As to whether walking combats obesity, here are two studies on the topic:

      One suggesting that walking has a positive effect on reducing obesity:
      http://newsroom.heart.org/pr/aha/walking-may-lessen-the-influence-230079.aspx

      And one that suggests it has a more mixed role:
      http://www.sciencedirect.com/science/article/pii/S0091743508002041

  • Abehrer

    I don’t mean to suggest that walking will solve obesity by itself, or that filling food deserts is not part of the solution. Rather, they are each an element of a multi-part solution. As is, almost certainly, diet modifications of the nature that Gary Taubes suggests. His suggestion that increased exercise causes increased appetite true but that does not mean, automatically, an increased consumption of calories. If that were the case exercise would never lead to weight loss, which it clearly does in some (many) cases.

    As to whether walking combats obesity, here are two studies on the topic:

    One suggesting that walking has a positive effect on reducing obesity:
    http://newsroom.heart.org/pr/aha/walking-may-lessen-the-influence-230079.aspx

    And one that suggests it has a more mixed role:
    http://www.sciencedirect.com/science/article/pii/S0091743508002041

    • Jacob AG

      Taubes admits early in “What Makes Us Fat” and “Good Calories, Bad Calories” that diet and exercise can and does lead to weight loss, only that it’s very inefficient relative to tinkering with insulin levels (there are many studies — Fogelholm and Kukkonen-Harjula in 2000, Williams and Wood in 2006, the AMA and the ACSM in 2007, etc. — that suggest exercise can and does lose weight, but that it’s surprisingly unimportant when it comes to reducing obesity). And he’d agree that a comprehensive approach to obesity is necessary.

      For example, here’s the punchline from the first study you cited above, the one suggesting that walking has a positive effect on reducing obesity (not the one suggesting mixed results):

      “The equivalent of brisk walking one hour a day was associated with a 0.06 kg/m2 reduction in the genetic effect on BMI”

      …0.06kg/m2 is basically nothing. A kg is about 2.2 pounds, and a meter is about 3 feet. I’m 6’2″, about 2 meters tall, so I’d lose (assuming the association is causal) something like half a pound overall as a result of walking 1 hour per day, 7 days a week. Even if I walk for 8 hours a day (not one), I’d still only lose about 4 pounds, *total*. Weak!

      Now you could say that this study only looks at how walking affects the genetic component of BMI, and ask “what are the non-genetic factors affecting BMI, and how would walking interact with those effects?”

      …and I’d hypothesize that the effect of rigorous exercise on non-genetic effects would be similarly close to zero. Not zero, but shockingly low given what you see on shows like The Biggest Loser and hear from the USDA. There is a theoretical and an empirical explanation as to why, but just read Taubes!

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