This is the third column in a series focusing on the economics of bicycling. Part 1 is "How bicycling will save the economy (if we let it)." Part 2 is "Tearing down freeways to make room for a new bicycle economy."

In the United States, we have the most expensive health care system in the world.

We collectively invest more than 15 percent of our GDP — that's around $ 2 trillion, or $ 5,700 per person — into health care every year.

The tragedy of these enormous numbers is that they fail to stem the tide of our increasing ill health. "Most of the money we're spending on health care is going to treat preventable chronic diseases," Michael Pollan told Grist in 2009. Our poor diet, he added, is responsible for most of those illnesses.

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