Additional people on the planet will put increasing pressure on food, water and other resources. As we zoom toward the projected figure of nine billion people by 2045, a new study suggests there is another statistic to worry about – our weight.

If you weighed the earth's entire adult population, it would equal 287 million metric tons, according to the London School of Hygiene & Tropical Medicine (LSHTM) study. Eighteen and a half million tons of this is from people who are overweight or obese. In the United States, adults average 181 pounds, placing us just behind the Pacific Island nations of Micronesia and Tonga. If every country had the same average weight as the United States, it would be the equivalent of one billion extra people on the planet. Picture the scene in Wall-E where the super-sized people spend their time sitting and sipping super-sized drinks!

To dive into this disturbing reality further, take a look at the yearly obesity maps at the Centers for Disease Control and Prevention website. In 2000 there were no states with obesity rates of 30% while in 2010 there were 12. You can make this data personal by comparing your own weight – if you dare – to the average adult here.

A correlation with low gas prices

The study provides plenty of fodder for public health professionals but it also demonstrates the correlation between low gasoline prices and overweight adults. The U.S. and many of the other nations with the largest waistlines, including several Arab states, have low gas prices with the obvious result that the population walks less and drives more. While we already know that our cities and suburbs should encourage walking and biking, the sense of urgency this study provides is a welcome addition to the debates over both the future of our cities and our energy pricing system.