Which countries" citizens are the least physically active? Americans may have introduced the world to drive-throughs and the La-Z-Boy chair, but countries around the world certainly have embraced the art of sitting around. In Britain, for example, preparations for the the XXX Olympiad next week include a public campaign to fight obesity, with the most recent figures showing 26 percent of English adults are obese compared with 15 percent in 1993, the Washington Post's Anthony Faiola reported. From a Lancet study released Wednesday, here are the countries with the highest inactivity rates among their populations, by region: Darker red correlates with higher levels of physical inactivity. Lancet In Africa, Swaziland came out on top, with 69 percent. In Europe, as we reported, the Brits are among the most sedentary people, at 63.3 percent inactive. But they're actually doing somewhat better than a few of their southern neighbors: Malta's and Serbia's rates are 71.9 and 68.3 percent, respectively. Saudi Arabia is at 68.8 percent, nearly tying with Argentina, at 68.3 percent. Southeast Asia has the lowest overall proportion of inactive adults, but Maldives came in at 39 percent. Physical inactivity levels by region (Lancet) In the Western Pacific, the tiny islands of Micronesia come in first, at 66.3 percent. However, even the historically svelte and long-living Japanese have a relatively high 60.2 percent rate. And for more fun, check out the BBC's interactive tool, which will tell you which nation's people you resemble most in terms of weight and height. There's no one reason why one country's citizens might be more or less active than another's, but the researchers note that environmental factors, such as park trails, play a role in encouraging exercise, as do social supports and good genes. Meanwhile, stress and age can cause a drop in physical activity.