Almost half a billion adults—10% of the adult population worldwide—were obese as of 2008, a new study finds. That’s nearly twice the 1980 rate, reports Scientific American. On average, each decade has seen a body mass index inch up 0.4 to an average of 23.8 in 2008; a BMI of more than 25 is considered overweight, while more than 30 is labeled obese. "Obesity, high blood pressure, and high cholesterol are no longer Western problems or problems of wealthy nations," said a scientist.
With 34% of the population overweight, the US has the highest average BMI—more than 28 for both sexes—among high-income countries, as well as the highest average increase per decade. Japan has the lowest average adult BMI among those countries, at 24 and 22 for men and women, respectively.