The World Health Organization finalized guidelines Wednesday saying people should keep intake of added sugars to just 5 to 10 percent of overall calories, which translates to about 25 to 50 grams of sugar a day for most people. [...] that's one reason the U.S. Food and Drug Administration is proposing the first overhaul of nutrition labels in two decades. A container of Chobani's 0% fat Greek yogurt in black cherry flavor lists 17 grams (about 4 teaspoons) of sugar. A store brand of enriched white bread at the convenience store chain Duane Reade listed 2 grams (about half a teaspoon) of sugar for per serving (2 slices) Special K with Red Berries, for instance, has 9 grams (more than 2 teaspoons) per serving (1 cup), while Frosted Flakes has 10 grams (more than 2 teaspoons) of sugar per serving (3/4 cup). California Kitchen's BBQ Chicken microwavable pizza has 7 grams (almost 2 teaspoons) of sugar in a single-serving pie.