Obesity since the 1980s

In a recent article, Matthew Yglesias takes issue “that conventional wisdom seems to have settled on the idea that there was a sharp uptick in obesity starting around 1980.” He argues instead that body weights have been increasing for a long time, and that if we are looking for causes of weight gain and obesity, we need to take a longer view than simply asking “what changed” in 1980, which seems fashionable today in the Twittersphere.

Here are his final two paragraphs on possible drivers of weight gain over the past century.

“It just turns out that like a lot of things, this has some downsides. The question of what, if anything, to do about those downsides seems pretty difficult to me, but I don’t think its origins are a big causal mystery.

If anything, making the origins out to be some huge puzzle lends itself to the false suggestion that there’s a very simple and straightforward solution. The truth — that we are experiencing some downside to living in a society with a great deal of material abundance — is harder to wrestle with, since people would be pretty unhappy about policy changes that reversed the 100+ year trend toward food becoming tastier, more available, and more convenient.”

I agree - perhaps because it is awfully similar to the conclusion I reached back in 2013 in The Food Police. Here’s what I wrote then at the conclusion of the chapter on fat taxes.

“It is only reasonable that we eat a little more food when it costs less and give up manual labor when an air conditioned office job comes along. We can’t disentangle all the bad stuff we don’t like about obesity with all the good things we now enjoy, such as driving, eating snacks, cooking more quickly, and having less strenuous jobs. Yes, we can have less obesity, but at the costs of things we enjoy.

When you hear we need a fundamental change to get our waistlines back down to where they were three decades ago, beware that it might take a world that looks like it did three decades ago.”

We are unlikely to finding a simple, mono-causal explanation for the rise in obesity. That is perhaps best illustrated in the figure below from a 2006 paper by Keith et al. in the International Journal of Obesity, which plots obesity (the red dashed line with x’s) alongside either other factors that have been suggested as causes for obesity. Obviously, lots of strong positive correlations, but it shows the likely futility of finding one single, easy answer.

No, Farm Policy Doesn't Have Much to Do with Obesity

Yesterday, David Ludwig and Kenneth Rogoff, prominent pediatrician and economist respectively, published an article in the New York Times about obesity.  The following is a passage from the piece.  

“Farm policies have made low-nutritional commodities exceptionally cheap, providing the food industry with enormous incentive to market processed foods comprised mainly of refined grains and added sugars. In contrast, vegetables, whole fruits, legumes, nuts and high-quality proteins are much more expensive and, in “food deserts,” often unavailable. ”

The authors have already taken a bit of a beating about this on Twitter from the agriculturally-literate-intelligentsia. Why?  Because these sentences give the incorrect impression that farm policy is a major contributor to obesity.  That's not saying farm policies aren't inefficient, only that they do not have the effects many people claim they do.

Why would farmers support policies that would make commodities "exceptionally cheap" and thus lower their profits?  Yes, there are some policies that likely increase production beyond what would happen in an un-distorted market, but there are other policies that reduce production.  Take corn, for example, which is the largest agricultural crop in the U.S. in terms of value of production.  The existence of subsided crop insurance subsidies and commodity programs might increase the tendency to produce more than would otherwise be the case, but ethanol policies from the EPA re-direct much of that production to fuel rather than food. Moreover, there are countervailing policies such as the Conservation Reserve Program (CRP), which remove land from production.  In addition, sugar policies push the price of sugar up, not down.  

The authors also point to processed food as another big evil, but in so doing they (correctly) undercut the argument that farm policy is a major culprit.  How so?  Well, for every $1 we spend on food, only about $0.15 results because of the cost of the farm product.  The other 85% of the cost is from transportation, processing, packaging, marketing, retailing, etc.  As a result, changes in farm commodity prices have relatively small impacts on retail prices.  

Fruits and vegetables are indeed more expensive than many commodity crops, but that's because of biology not policy (see more on that here and here).  Here's what I wrote in one of those posts:

“why do we grow so much corn, soy, and wheat in the U.S.? A primary answer is that these plants are incredibly efficient at converting solar energy and soil nutrients into calories (they’re the best, really the best). Moreover, these calories are packaged in a form (seeds) that are highly storeable and easily transportable - allowing the calories to be relatively easily transported to different times and to different geographic locations. Contrast these crops with directly-human-edible fruits/vegetables like kale, broccoli, or tomatoes. These plants are poor converters of solar energy to plant-stored energy (i.e., they’re not very calorie dense), and they are not easily storeable or transportable without processing (mainly canning or freezing), which requires energy.”

If you don't believe me, there is a long literature by agricultural economists on this subject.  See this book by Julian Alston and Abby Okrent or these papers in American Journal of Agricultural Economics or Journal of Health Economics, the later of which was co-authored with Brad Rickard.  Other papers take entirely different approaches but arrive at the same conclusion.  See this paper in Food Policy by Corey Miller and Keith Coble or this one by Alston, Sumner an Vosti, also in Food Policy.

As for the efficacy of the other policies proposed by Ludwig and Rogoff, I'm skeptical of their efficacy in truly affecting obesity.  See this paper I recently published in Applied Economic Perspectives and Policy or my 2013 book, The Food Police.

Inequalities of Fat Taxes and Thin Subsidies

I was excited to see The Economist ran an article on my paper with Laurent Muller, Anne Lacroix, and Bernard Ruffieux, which appeared in the Economic Journal.  In typical Economist fashion, they didn't mention us by name, but here's their summary of our findings:

“The study found that the taxes and subsidies actually widened health and fiscal inequalities. Fat taxes meant the women on lower incomes paid disproportionately more for food—their habits changed less. They preferred to buy food they liked rather than what made nutritional sense. Taxing the food they eat most made the poor poorer.

Subsidies encouraged all income groups to buy more fruit and vegetables. But those on higher incomes proved more responsive and so benefited most. Interestingly, richer folk were also more likely to buy the subsidised healthy food and then spend the savings they had accrued on yet more healthy food. But poorer women, if they responded to lower prices, often used the money saved to buy unhealthy items or something else entirely. Once the nutritional price policies were applied, the average share of budget spent on healthy food actually increased for the better-off. ”

The Effects of Farm and Food Policy on Obesity in the United States

That's the title of a new book by Julian Alston and Abigail Okrent.  Right now it's only available as an ebook, but the hard copy should be out soon.  Here's the publisher's description.

“This book uses an economic framework to examine the consequences of U.S. farm and food policies for obesity, its social costs, and the implications for government policy. Drawing on evidence from economics, public health, nutrition, and medicine, the authors evaluate past and potential future roles of policies such as farm subsidies, public agricultural R&D, food assistance programs, taxes on particular foods (such as sodas) or nutrients (such as fat), food labeling laws, and advertising controls. The findings are mostly negative—it is generally not economic to use farm and food policies as obesity policy—but some food policies that combine incentives and information have potential to make a worthwhile impact. This book is accessible to advanced undergraduate and graduate students across the sciences and social sciences, as well as to decision-makers in the public, private, and not-for-profit sectors. ”

I had the pleasure of seeing a pre-release copy of the book and provided the following blurb:

“That obesity is a serious challenge in America is undeniable. Yet, appropriate policy responses are far less clear. The Effects of Farm and Food Policy and Obesity is a tour de force. Alston and Okrent provide a solid economic framework for thinking about obesity policies, bust myths about the causes of the problem, and offer nuanced solutions. The book is a must read for anyone seriously interested in role of food and agricultural policy in addressing obesity.”

Economics and Obesity Policy

The International Journal of Obesity just released a a short review paper I was invited to write, which discusses the economics of policies aimed at reducing obesity. In the paper, I touch on the economic approach for thinking about government intervention in this space and whether there are market failures that would justify intervention.  I then move on to discuss a variety of specific issues that are often discussed in relation to obesity such as farm policy, soda taxes, healthy food subsidies, food assistance programs (and proposed restrictions on them), and information policies. 

Here is the conclusion:

“This article presented a somewhat pessimistic view on the ability of government policy to substantively influence obesity prevalence. Obesity is a complicated and multifaceted issue. So too are the effects of anti-obesity policies. One response is to argue for an all-out ‘war’ on obesity. It probably is true that government policy mandating what farms grow, restricting the
supply and type of food to consumers, and controlling prices, offerings and advertisements by food manufacturers could reduce obesity prevalence. But, is this the type of coercive
society in which we would like to live? Society faces very real tradeoffs between economic freedom, technological progress, and obesity prevalence. These sorts of tradeoffs are unfortunate, but they reflect very real constraints to effective economic policy making.”

My paper joins several others that critically evaluate anti-obesity policies.