New York City's mayor is proposing a ban on the sale of large sodas and other sugary drinks in the hopes of combating obesity _ an expansion of efforts to encourage healthy behavior that have led to shouts that America's largest city is becoming a "nanny state."

The proposed first-in-the-nation ban _ formally announced Thursday at the headquarters of Mayor Michael Bloomberg's administration _ would impose a 16-ounce (.4-kilogram) limit on the size of sweetened drinks sold in the city's restaurants, shops and movie theaters. It is the latest health effort by the administration to spark accusations that the city's officials are overstepping into matters that should be left in the hands of individual consumers.

Under Bloomberg, a three-term mayor, New York has campaigned aggressively against obesity, including outlawing trans fats in restaurant food and forcing chain restaurants to post calorie counts on menus. The mayor has also led efforts to ban smoking in the city's bars, restaurants, parks and beaches.

City officials say they believe such a ban would prove popular with residents and start a national trend. But it already has opponents.

"There they go again," said Stefan Friedman, spokesman for the New York City Beverage Association. "The New York City Health Department's unhealthy obsession with attacking soft drinks is again pushing them over the top. The city is not going to address the obesity issue by attacking soda because soda is not driving the obesity rates."

But City Hall officials, citing a 2006 study, argue that sugary drinks are the largest driver of rising calorie consumption and obesity. They note that sweet drinks are linked to long-term weight gain and increased rates of diabetes and heart disease.

Bloomberg said Wednesday that he "thinks it's what the public wants the mayor to do."

The proposal drew strong reaction from the Coca-Cola Company.

"The people of New York City are much smarter than the New York City Health Department believes," the company said in a statement. "We are transparent with our consumers. They can see exactly how many calories are in every beverage we serve."

The ban would apply only to drinks that contain more than 25 calories per 8 ounces (227 grams). I would not apply to diet soda or any other calorie-free drink. Any drink that is at least half milk or milk substitute would be exempted.

The ban, which could take effect as soon as March, would not apply to drinks sold in grocery or convenience stores that don't serve prepared food. Establishments that don't downsize would face fines of $200 after a three-month grace period.

The proposal requires the approval of the city's Board of Health _ considered likely because its members are all appointed by Bloomberg.

Bloomberg often cites the city's rising life expectancy numbers as proof the health push is working, but his efforts have drawn criticism from others who accuse him of instituting a "nanny state."

His administration has tried other ways to make soda consumption less appealing. The mayor supported a state tax on sodas, but the measure died in the legislature, and he tried to restrict the use of food stamps to buy sodas, an idea that federal regulators rejected.

___

Follow Samantha Gross at http://www.twitter.com/samanthagross