When New York City announced in September it will ban sugary beverages larger than 16 ounces in restaurants, sports arenas and other public venues, critics complained that the city has no right to meddle with individual food choices. Many public-health advocates, however, praised the move as an important step toward slowing the nation's decades-long rise in obesity rates. Sugar-sweetened drinks add an average 300 calories a day to teens' diets without providing any nutrition, they say. Some scientists even hypothesize that fructose, the main sweetener used in sodas, may trigger diseases such as Type 2 diabetes, which is also on the rise. Other nutrition experts, however, say sugar can't be the only or even the primary culprit in the nation's skyrocketing obesity rates, since they have doubled since 1980 while sugar in sodas and other packaged foods has increased by a much smaller percentage over that period.