# Weighty Problem

As Brooke notes below, obesity has been tied to global warming.  One of the lessons obesity campaigners drew from that study was that losing weight saves you gas money and that the US uses 938 million more gallons of gas a year because of the extra weight gain since 1960.  The often excellent env-econ blog had something to say about that:

Let’s say that a typical new car sold these days weighs about 4000 pounds. A 50 pound increase (one heavier male, one heavier female) is a 1.25 % increase in total weight. If the gasoline savings are about 1%, the elasticity of gas to weight (% change in gasoline divided by the % change in weight) is 0.80.

Hmmm. Maybe the estimate ain’t so crazy.

Extrapolating, if the typical car turns into a typical car sold 25 years ago (3200 pounds), a 20% decrease in weight, then fuel consumption would fall by 16%, or 22 billion gallons. At \$2.50 per gallon, that is an \$56 billion decrease in gas consumption (assuming no behavioral change as cars get smaller). The average household would save almost \$1900.

The moral of the story? If you want to save money, don’t bother losing 25 pounds. Instead, buy a smaller car and squeeze your-heavy-self in.

Of course, down-sizing the auto fleet has safety consequences.  The National Academies concluded that the reduction in weight of American cars since the introduction of fuel economy regulations had led to 2000 extra deaths on the road every year.