(Melina Mara/The Washington Post)
The link between such subsidies and obesity is highly tenuous, according to a study that analyzed the effects of price supports on diet. In fact, if all subsidies were magically erased — including trade barriers — the typical American adult would actually respond by eating about 3,000 to 3,900 additional calories a year: A cutting back on grains and meats, today artificially cheap, would be more than offset by the eating of more sugar and dairy products, now artificially expensive (and especially calorie-dense).

It’s worth breaking this down a bit: Subsidies that boost the production of foods like soy and grains do cause people to consume more calories. And trade barriers on foods like sugar cause Americans to eat fewer calories. Okay, no surprise there. What’s interesting, though, according to this study, is that the overall effect is tiny either way (about 10 extra calories per day all told). What’s more, the authors, Bradley Rickard, Abigail Okrent and Julian Alston, found that obesity rates have soared even as price supports have declined since 1988.

Now, this isn’t an argument for keeping all crop subsidies in place (and the authors don’t claim to be defending price supports). For instance, one recent study by advocacy groups found that, between 1995 and 2010, $16.9 billion in federal subsidies went toward producers of corn syrup, high fructose corn syrup, cornstarch and soy oils. That, in turn, helps underwrite the consumption of junk food. The net effect on calorie consumption might be fairly minor, but that doesn’t mean it’s a good investment — or a particularly healthy one.