I'm not disputing that the environment has changed in ways that seem to make people get fatter--indeed, you'd have to be a total moron to dispute this. Nor am I disputing that some of this can be laid at the door of government, like our ridiculous agriculture subsidies, and even our zoning laws. On the other hand, it's also true that people really liked riding around in cars even before zoning--unless the landscape makes car ownership prohibitively expensive, people tend to embrace it, which is why car ownership is increasing so fast even in places like Europe. Either way, this cannot be the only reason. US government policy and bad zoning is not making people fat in Britain or Australia.

Marc adds:

Lo and behold, government policy has helped ensure that the raw foodstuffs that go into all the starchy, sugary foods that we eat are much cheaper. And when compared to the consumer price index, fruits, vegetables and healthy foods are more expensive than they were 30 years ago. If government policy influences diet on a macro scale, and if there is evidence that the diet is harmful, then, in theory, there would be no additional intervention if, say, Congress began to subsidize tomatoes in the same way it subsidizes corn, just a change in policy.

None of this argues for a soda tax, or a tax on sugar, or a ban on, say, food marketing to children. It's just to say that if the obesity epidemic was nurtured by policy -- and it clearly was -- perhaps it can be undone by policy, too.



I think this is really, really optimistic. First of all, while it is true that produce has outpaced snack foods in the CPI-U, there's reason to think that this is a statistical artifact of the way that CPI is calculated. We have more fresh food available than ever before--year round raspberries, seventeen kinds of lettuce--and a lot more value-added products such as baby carrots and pre-washed lettuce. When people pay more for unseasonable produce or prepped vegetables, this shows up as an increase in the rate of cost inflation. If you look at the aggregate figures, we see that since the early 1980s (the time period from which the per-capita increases are usually quoted), per-capita consumption of fresh produce, particularly fresh vegetables, has increased dramatically.

The problem with all these sorts of theories is that they do an okay job explaining the latitudinal data--we're fat, we're subsidizing roads, we're subsidizing corn, so that must be making us fat!--but they don't explain the trend. I have not done an exhaustive survey, but I've been unable to find any study that even attempts to establish in any sort of rigorous way that Americans have become more sedentary in, say, the last twenty or thirty years.

The data is even less persuasive for other candidates. Corn, and simple starches more broadly, have been the cheapest part of the American diet for centuries. As a child, my mother didn't get any fresh vegetables at all eight months out of the year, because they simply weren't available. She got frozen or canned, but their two winter staples were sugared homemade applesauce and butternut sqaush, both of which are basically pure simple carbohydrate. Lean chicken was pricier than beef, but fatty pork was cheaper than either. Look in a cookbook from the thirties or fifties and you'll find that recipes for some sort of mostly starch dish are at least 65% of the book. And those weren't healthy whole grains, either. They were white flour, or rice, richly laced with fat and sugar.