The global obesity epidemic is one of the greatest health challenges facing humanity. Some 600 million, or 13 percent, of the world's adults were obese in 2014—a figure that had more than doubled around the globe since 1980. At present, 37 percent of American adults are obese, and an additional 34 percent are overweight. If current trends continue, health experts predict that half of all Americans will be obese by 2030.