Overweight? Blame It on CO2

Why are we fat? It's just something in the air, researchers say—namely carbon dioxide. A Danish researcher found that subjects' weight gain over two decades matched the increase in carbon dioxide over the same period, the Daily Mail reports. What's more, between 1986 and 2010, American obesity increased the most on the East Coast, which has the highest levels of CO2. The researcher speculates that carbon dioxide affects certain hormones in the brain that dictate how much food we eat and energy we expend.

To test the theory, researchers put six men into different climate-controlled rooms; some were exposed to extra carbon dioxide. Afterward, the men were asked to eat as much as they wanted. Those who'd experienced the higher CO2 ate 6% more than their peers. The Mail offers an addendum to all this: Researchers in Scotland say that if every overweight person on the planet shed 22 pounds, it would cut CO2 emissions by some 50 metric tons, or 0.2% of global emissions in 2007. Click for more. (More Denmark stories.)