While the rates of obesity have leveled off in some countries where it's already a public health concern, other places are seeing their obesity rates increase, propping up the global average. "Over the past four decades, we have transitioned from a world in which underweight prevalence was more than double that of obesity, to one in which more people are obese than underweight," according to a study published in The Lancet. By 2025, one-fifth of adults around the world are forecast to be obese, including 40% of adults in the U.S. Related tickers: PLNT, FIT, WTW, NUTR, NTRI, HLF, VVUS, ARNA, GNC, MED, NATR, OREX, LTM, FINL