Collectively, as a nation, we eat a lot of food. A lot of high-fat, high-sugar bad-for-us, questionable food. Scientists of every stripe are always asking why we do this to ourselves. The answer? It might be as simple as: because we can afford to.

The Pew Research Center today points to a study showing that Americans are spending less money than ever on food, comparatively speaking.

We still spend millions and billions of dollars on food, of course, but it’s become an ever-smaller amount of the cash we spend in general. The average American household now spends about 10% of its disposable income on food, Pew says, where in the 1930s it was at least a quarter.

The problem of averages being averages still applies, though: food costs are not so low for everyone. The poorest 20% of Americans, Pew says, still spend a solid third of their income trying to stay fed.

In general, every dollar simply buys more calories than it used to. Of course, we don’t all, strictly speaking, need every calorie we consume. As is often reported, obesity rates in the U.S. have also skyrocketed through the 20th century and into the 21st, as the cost of food in general has reached historical lows.

“So why doesn’t everyone just eat right and exercise more?” you may ask. Well it turns out, we do that, too: in a 2009 study, Pew says, over 51% of Americans reported getting regular physical exercise. And collectively, we also buy more fresh fruits and vegetables than we did thirty or forty years ago.

But that doesn’t seem to stop us from exercising the buying power of our dollar to buy the bad stuff all the time. And it’ll probably take a few marathons more than most of us will ever run to make up for a triple cheeseburger served between donuts.

Chart of the Week: Is food too cheap for our own good? [Pew Research Center]

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