Chain of Evidence

From CNN, a story suggesting that Oregon's emphasis on pedestrian and bike-friendly cities has helped it keep obesity in check.

According to a study released Tuesday by the Washington, D.C.-based Trust for America's Health, the percentage of overweight Oregonians held steady at 21 percent last year, a sharp contrast to Alabama, where the rate of obesity increased 1.5 percentage points to 27.7 percent.

What makes Oregon different is its emphasis on urban design, which encourages outdoor activities like biking to work, the study's authors said.

Now, obviously, only a small share of Oregon residents walk or bike to work; and many people who do so have farily short commutes. But that's exactly the point:  when it comes to obesity, even a little bit of exercise can make a big difference.  On average, adults put on a pound or two a year -- but a pound of extra weight per year averages out to just 10 calories per day.  That's less than a teaspoon of sugar, or a daily stroll of about a tenth of a mile.  So even though Oregon cities' neighborhood design may have only a small effect on walking and biking, that effect could very well have been enough to keep Oregonians from putting on as much weight as Alabamans.  And by curtailing the growth of obesity, Oregon may have helped keep its citizens healthy, while stemming health care costs--which now account for about one out of every eight dollars Oregonians earn.  Which is one way of responding to people who question whether sidewalks and bike lanes are really worth the cost.