Wednesday, September 12, 2007

Why Rising Gasoline Prices Are Good For You

No, seriously! An economist claims that rising gasoline prices reduces obesity:
Science Daily — Just as rising gasoline prices are forcing many Americans to tighten their financial belts, new research suggests higher fuel costs may come with a related silver lining — trimmer waistlines.

"An additional $1 in real gasoline prices would reduce obesity in the U.S. by 15 percent after three years," suggests Charles Courtemanche, an economics researcher at Washington University in St. Louis.

Higher gas prices could result in trimmer waistlines, suggests a WUSTL researcher.

"In fact, about 13 percent of the rise in obesity between 1979 and 2004 can be attributed to falling real gas prices during the period."

Courtemanche's conclusions are based on a comparison of average state fuel prices with health behavior trends documented in government surveys covering two decades, 1984-2004. He provides evidences for two direct and causal links between gasoline prices and obesity.

"If the price of gas rises, the cost of driving also rises, which may affect body weight in two ways," Courtemanche explains.

"First, people may substitute from driving to walking, bicycling, or taking public transportation. Walking and bicycling are forms of exercise, which increase calories expended, decreasing weight.

"If a person uses public transportation, such as subways, buses, trolleys, or rail services, the need to move to and from the public transit stops is likely to result in additional walking, again decreasing weight.
I find this claim implausible. Like nearly all human behavior changes caused by financial incentives, it operates at the margins. Where I live, the only regular destination that I can reach by foot rather than by car is my mailbox, which is a bit more than half a mile away. When I lived in West Boise, my job was 1 1/2 miles away. While I very occasionally walked or bicycled, cost was not a factor in the decision--simply because driving 1 1/2 miles was very, very cheap (about 3 1/2 gallons a month), and unless gasoline rose by $10 per gallon, the reduced driving cost was more than made up for with the inconvenience of not being to zip home to have lunch with my wife, and the cost of eating in the company cafeteria.

Even a ten mile each way commute is only 440 miles per month; for a 20 mpg car, that's 22 gallons a month of commute cost. Even a $1 per gallon price increase is only $22 per month (and assuming that mass transit alternatives don't increase in response to rising gasoline prices). It is hard to imagine anyone but the most desperately poor commuters would be influenced by such a paltry amount to give up the convenience of driving to work and back in one's own car.

I can easily see how people who live more than fifty miles from work, and have rapid transit as a realistic alternative, might be encouraged by rising gasoline prices to not drive. Fifty miles each way to work is 2200 miles a month; in a 20 mpg car, that's 110 gallons per month, and a $1 per gallon increase would mean $110 extra month. Maybe that makes a big difference for people who live in the Northeast, or the San Francisco Bay Area, where a 50 mile commute isn't all that unusual, and there are realistic mass transit alternatives available. In most of America, people with 50 mile commutes don't have bus service available, and very few are going to bicycle or walk to work.
"Second, since the opportunity cost of eating out at restaurants rises when the price of gas increases, people may substitute from eating out to preparing their own meals at home, which tend to be healthier. People may also eat out less in an effort to save money to pay for the increased cost of gas."
This I find this a more plausible explanation. If you live in suburbia or in a rural area (like I do), there are very, very few choices within walking distance. (For me, the only walking distance eating establishments involve road kill--although I did bicycle down to breakfast in Horseshoe Bend once.) It is conceivable that some people, after paying the extra cost of gasoline, may decide that they can't afford to eat out, and instead of gorging themselves at McDonald's or a nice restaurant, stay home instead.

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