One more reason to pass up that double cheeseburger? That's up to you - but a professor at the University of Illinois has calculated the impact of America's obesity problem on our fuel consumption, and it ain't pretty.
According to Sheldon Jacobson, more than one billion gallons of excess fuel per year are attributable to our bulging waistlines, and he found that just over the past two years our fat-fueled inefficiency has been increasing.
But could we turn that into fat-fueled efficiency instead? Barbara Ehrenreich suggests jokingly (or is it?) that we could liposuction all the extra fat and use the resulting oil to power our cars. Although this is a one-time non-renewable solution, and the amount of fat available may not make a huge impact in itself, remember that every ounce converted to fuel would at the same time increase effinciency - double dipping, but in a good way!
UPDATE 12/23: Maybe Barbara Ehrenreich was joking, but a doctor in California actually took her up on it - only to be forced to shut down because lipo-ed human fat is "medical waste" which is not legal for repurposing... yet.