The World Is Fat (Especially America)

The world could stand to shed a few pounds. Fifteen million metric tons, in fact, according to a new study.

In the study, published in the open-access journal BMC Public Health, researchers used country-specific data on body mass index and heights to estimate the biomass of the world’s entire adult population.

They concluded that in 2005, the global adult human biomass was about 287 million metric tons. (A metric ton is 1,000 kilograms, or about 2,200 pounds.) About 15 million metric tons of that biomass were the extra pounds of people who were overweight (here defined as having a body mass index value above 25). About 3.5 million metric tons of that total biomass were because of obesity (having a B.M.I. above 30).

The United States is to blame for a lot of those spare tires. While America holds about 5 percent of the world’s adult population, it accounts for about a third of the excess weight because of obesity.

If, on the other hand, all countries were about as overweight as the United States, total biomass across the globe would increase by 58 million metric tons, or about 20 percent.

These numbers matter not only because of the health concerns over obesity. They matter also because of the energy required to feed people who are obese.

“Tackling population fatness may be critical to world food security and ecological sustainability,” the authors conclude.