Which other government programs are us fat?

A few days ago, I took on the claim that farm subsidies are making us fat (the answer is most likely "no").  However, there are other government programs that potentially affect food prices - what about those programs?  Have they contributed to the rise in obesity?

A new paper in by Julian Alston, Joanna MacEwan, and Abigail Okrent in Applied Economic Perspectives and Policy asks whether funding for agricultural research and development (R&D) can explain the rise in obesity.  The chain of logic goes like this: there is extensive evidence that funding for agricultural research increases productivity; higher productivity means getting more food using fewer resources; more food means lower food prices; more food at lower prices means more food intake; more food intake leads to obesity.  Ergo, government funding for agricultural research leads to obesity.  

So what did the authors find?  They found that agricultural R&D spending probably did have a modest effect on obesity rates, but that R&D also resulted in enormous benefits to consumers and producers.  The authors write:

“Our analysis of historical counterfactuals suggests that it would have been very expensive to have foregone past R&D-induced productivity growth, even if in doing so we were able to reduce obesity and related healthcare expenditures.”

And, if we had undone the R&D efforts that led to the food price changes since the 1980s:

“This would be a costly reversion; it would cost consumers $65.01 billion, of which only $4.72 billion would be offset by savings in public healthcare costs, to reduce average U.S. adult body weight by 4.85 lbs. This translates to a cost of $55.6 per pound after the savings in public healthcare costs are taken into account.”

In summary:

“The implication is that agricultural R&D policy is unlikely to be an effective policy instrument for reducing obesity, both because the effects are small and because it takes a very long time, measured in decades, for changes in research spending to have their main effects on commodity prices. Moreover, as our results and others have shown, the opportunity costs of reducing agricultural research spending in the hope of eventually reducing the social costs of obesity would be very high because agricultural research yields a very large social payoff.”

Having now discussed the effects of farm subsidies and agricultural research, what about programs like the government-sanctioned check-off programs?  That was the topic of a session at the most recent AAEA meetings in Boston.  Parke Wilde from Tufts and Harry Kaiser from Cornell debated the role of check-off programs and their role in affecting public health and nutrition.  I was unfortunately unable to attend the session, but Parke offered a preview of it on his blog.  I hope to see some research on this topic in the near future.  

Are Farm Subsidies Making Us Fat?

In the past couple weeks, there have been a number of popular press articles suggesting that farm subsidies are a big part of the reason Americans eat unhealthy and are overweight. Here's the title from the New York Times: "How the Government Supports Your Junk Food Habit", and Fox News: "Government heavily subsidizes junk food, report suggests", and NPR: "Does Subsidizing Crops We're Told To Eat Less Of Fatten Us Up?". All the hubbub seems to stem from this article by some CDC researchers in JAMA Internal Medicine, which shows people who are more overweight tend to get more of their calories from foods that happen to be subsidized.

But, as we should all know by now, correlation is not causation.  Here's Tracie McMillian in a piece for National Geographic:

“But what the study does not show is the degree to which subsidies—and, in particular, the ones that are currently in place—actually persuade people to eat more of those foods. The researchers, by the way, admit this: “We cannot say [the link between subsidies and consumption] is causal from this study,” says K.M. Vankat Narayan, a lead author.

So while there’s an accepted correlation between low prices and increased purchases, nobody really knows how much farm subsidies matter when it comes to which foods people buy—and eat.”

She's right on the first part and wrong on the second.  There are actual lots of people who know how much farm subsidies contribute to food consumption, and they're called agricultural economists (in fact, McMillian goes on to then cite two prominent food and agricultural economists on the issue: Parke Wilde and David Just).  My view is in line with Wilde's and Just's:

“Indeed, in contemporary America, “the potential impact of the agricultural subsidies on consumption right now is inconsequential,” argues David Just, an agricultural and behavioral economist at Cornell University. Subsidies for farmers are unlikely to have much impact on consumer prices, adds Wilde, because farmers’ share of what we pay at the store is so little. ”

Let me pause right here and say that the question of the causal relationship between farm policy and unhealthy food consumption is an empirical, positive question, not a normative one.  There are a variety of reasons one may think we should or should not have farm subsidies (I generally find myself in the latter camp for reasons I won't go into here), but for the moment let's set the "should" question aside and ask what the evidence actually says on the link between farm subsides and unhealthy eating.  

Here's what I wrote on the issue in a recent Mercatus paper (which came out well before all the JAMA paper and the resulting news stories):

“Despite popular claims to the contrary, research suggests that farm subsidies have likely had little to no effect on obesity rates. First, although such policies may have had some effect on farm commodity prices, these inputs account for only a small share of the overall retail cost of food. For example, in 2013, only 7 percent of the retail price of bread was a result of the farm-gate price of wheat and other agricultural commodities. Even the enormous price swing that took wheat from around $3 per bushel in 2006 to almost $12 per bushel in February 2008 (a 300 percent increase) would be expected to increase the price of bread by only about 14 percent. Second, agricultural policies are mixed, and some policies (such as those for sugar, ethanol promotion, and the Conservation Reserve Program, or CRP) push the prices of agricultural commodities up rather than down. Third, despite the widely varying agricultural policies across countries and over time (see figures 14–16), those policies do not correlate well with differences in food prices and obesity rates across countries or with changes in obesity rates over time.”

In the model I used for the forthcoming paper I wrote on the distributional impacts of crop insurance subsidies, I find that the complete removal of crop insurance subsidies to farmers would only increase the price of cereal and bakery products by 0.09% and increase the price of meat by 0.5%, and would also increase the price of fruits ad vegetables by 0.7%.  So, while these policies may be inefficient, regressive, and promote regulatory over-reach, their effects on food prices are tiny, and depending on which policy we're talking about, could push prices and consumption  up or down.  

For those truly interested, here's a small list of academic papers by economists on the relationship between farm policy and obesity/health (for links to the actual papers, just do a quick googlescholar search).

Alston, Julian M., Daniel A. Sumner, and Stephen A. Vosti, “Farm Subsidies and Obesity in the United States: National Evidence and International Comparisons,” Food Policy 33, no. 6 (2008): 470–79. 

Balagtas, J.V., Krissoff, B., Lei, L. and Rickard, B.J., 2014. How Has US Farm Policy Influenced Fruit and Vegetable Production?. Applied Economic Perspectives and Policy, 36(2), pp.265-286.

Beghin, John C., and Helen H. Jensen. "Farm policies and added sugars in US diets." Food Policy 33, no. 6 (2008): 480-488.

Miller,J. Coreyand Keith H. Coble, “Cheap Food Policy: Fact or Rhetoric?” Food Policy 32, no. 1 (2007): 98–111. 

Okrent, Abigail M.  and Julian M. Alston, “The Effects of Farm Commodity and Retail Food Policies on Obesity and Economic Welfare in the United States,” American Journal of Agricultural Economics 94, no. 3 (2012): 611–46.

Rickard, B.J., Okrent, A.M. and Alston, J.M., 2013. How have agricultural policies influenced caloric consumption in the United States?. Health Economics, 22(3), pp.316-339.

Zilberman, D., Hochman, G., Rajagopal, D., Sexton, S. and Timilsina, G., The impact of biofuels on commodity food prices: Assessment of findings. American Journal of Agricultural Economics, 95, no. 2 (2013) : 275-281.

Does Diet Coke Cause Fat Babies?

O.k., I just couldn't let this one slide.  I've seen the results of this study in JAMA Pediatrics discussed in a variety of news outlets with the claim that researchers have found a link between mothers drinking artificially sweetened beverages and the subsequent weight of their infants.

I'm going to be harsh here, but this sort of study represents everything wrong with a big chunk of the nutritional and epidemiology studies that are published and how they're covered by the media.  

First, what did the authors do?  They looked at the weight of babies one year after birth and looked at how those baby weights correlated with whether (and how much) Coke and Diet Coke the mom drank, as indicated in a survey, during pregnancy.  

The headline result is that moms who drank artificially sweetened beverages every day in pregnancy had slightly larger babies, on average, a year later than the babies from moms who didn't drink any artificially sweetened beverages at all.  Before I get to the fundamental problem with this result, it is useful to look at a few more results contained in the same study which might give us pause.

• Mom's drinking sugar sweetened beverages (in any amount) had no effect on infants' later body weights.  So drinking a lot of sugar didn't affect babys' outcomes at all but drinking artificial sweeteners did?
• The researchers only found an effect for moms who drank artificially sweetened beverages every day.  Compared to moms who never drink them, those who drink diet sodas less than once a week actually had lighter babies! (though the result isn't statistically significant).  Also, moms drinking artificially sweetened beverages 2-6 times per week had roughly the same weight babies as moms who never drank artificially sweetened beverages.  In short, there is no evidence of a dose-response relationship that one would expect to find if there was a causal relationship at play.  

And, that's the big issue here: causality.  The researchers have found a single statistically significant correlation in one of six comparisons they made (three levels of drinking compared to none for sugar sweetened beverages and for artificially sweetened beverages).  But, as the researchers themselves admit, this is NOT a casual link (somehow that didn't prevent the NYT editors from using the word "link" in the title of their story).  

Causality is what we want to know.  An expecting mother wants to know: if I stop drinking Diet Coke every day will that lower the weight of my baby?  That's a very different question than what the researchers actually answered: are the types of moms who drink Diet Coke every day different from moms who never drink Diet Coke in a whole host of ways, including how much their infants weigh?  

Why might this finding be only a correlation and not causation? There are a bunch of possible reasons.  For example, moms who expect their future children might have weight problems may choose to drink diet instead of regular.  If so, the the moms drinking diet have selected themselves into a group that is already likely to have heavy children.  Another possible explanation: moms who never drink Diet Cokes may be more health conscious overall.  This is an attitude that is likely to carry over to how they feed and raise their children which will affect their weight in ways that has nothing to do with artificially sweetened beverages.

Fortunately economics (at least applied microeconomics) has undergone a bit of credibility revolution.  If you attend a research seminar in virtually any economist department these days, you're almost certain to hear questions like, "what is your identification strategy?" or "how did you deal with endogeneity or selection?"  In short, the question is: how do we know the effects you're reporting are causal effects and not just correlations.  

Its high time for a credibility revolution in nutrition and epidemiology.  

Optimal fat tax

In the Washington Post article Catherine Rampell raises an important point with regard to the emerging debate over whether to tax soda.  

“Instead of arbitrarily singling out one category of bad foodstuff for taxation — and the categories of bad foodstuffs will always be somewhat arbitrary — a more effective route to reducing consumption of excessive sugar or calories might be a universal, graduated sugar or calorie tax.

But even that still doesn’t quite seem fair or, for that matter, efficient. After all, a calorie tax would also hit people who consume more calories because they are very active, such as marathoners. Besides being regressive, a tax on calories or sugar would also effectively, if unintentionally, make it more expensive for trim people to exercise.

In other words, a lot of inputs go into determining whether a person is obese. Taxing some of those inputs distorts the relative prices of those inputs, but it doesn’t necessarily change the desired output: obesity rates.

Which raises the question: Why not just target the output, rather than some random subset of inputs? We could tax obesity if we wanted to. Or if we want to seem less punitive, we could award tax credits to obese people who lose weight. A tax directly pegged to reduced obesity would certainly be a much more efficient way to achieve the stated policy goal of reducing obesity.”

Yet, people don't seem to like the idea of a fat-person tax.  Why not?

“Maybe it’s because they’re regressive (but so are soda taxes). Maybe it’s because it sounds like we’re shaming fat people (but arguably so does any policy aimed at reducing obesity). Maybe it just feels unfair to tax people based in any way on their genes, which, like diet and exercise, can also be a determinant of weight.

But if we assume it’s impossible for obese people to lose weight by any combination of inputs they do have control over, it’s hard to simultaneously argue that making one of those inputs more expensive could lead to some nationwide weight-loss miracle. Pop goes the pop-tax rationale.”

100 year old fat tax

Thanks to David Allison and his colleagues' weekly email summarizing the latest research on obesity, I ran across this policy proposal in the British Medical Journal from 1904.  If you can't read the fine print, it says, in part, "A superfluity of fat, which is mostly the result of luxurious living, may therefore not unfairly be regarding as a fitting object of taxation."  You're off the hook if you weigh less than 135 lbs.