If you use food stamps, some purchases are off-limits, including cigarettes and booze. New York City is seeking permission to add another no-no to that list: soda and other sugared drinks.

The New York Times reports that the city, in a bid to combat obesity and related illnesses, has requested federal permission to bar its 1.7 million food stamp recipients from using the government assistance to buy sugared drinks. The proposal calls for a two-year ban, to provide time to study the impact on health and to determine whether the restriction should be made permanent.

In a statement, Mayor Michael R. Bloomberg called sugar-sweetened beverages “the largest single contributor to the obesity epidemic” and said the rule would “give New York families more money to spend on foods and drinks that provide real nourishment.”

As mayor, Bloomberg has pushed steps to improve the health of New Yorkers, including the city’s expansion of smoking restrictions to almost all indoor public places. The city also has banned trans fats in restaurants and required restaurants to post calorie counts.

Still, some public health experts and welfare advocates objected to putting further restrictions on food stamp purchases. “The world would be better, I think, if people limited their purchases of sugared beverages,” said George Hacker, a public health expert at the Center for Science in the Public Interest. “However, there are a great many ethical reasons to consider why one would not want to stigmatize people on food stamps.”

Marion Nestle, a nutritionist and critic of the junk food industry, wrote on her blog that incentives might be a better option. “Make the [food stamp] benefit worth twice as much when spent for fresh (or single-ingredient frozen) fruits and vegetables.”

The New York proposal, which is being considered by the U.S. Department of Agriculture, would cover drinks with more than 10 calories per eight ounces, but would not apply to milk products, milk substitutes or no-sugar-added fruit juices.

In 2004, the department denied a request by Minnesota to ban the purchase of junk food with food stamps, saying it would “perpetuate the myth” that food-stamp users made poor food choices, the Times reports.

Recent statistics show that nearly four in 10 public-school children in kindergarten through eighth grade in New York City are overweight or obese. The number of New Yorkers who qualify for food stamps has grown more than 35 percent in recent years, mirroring the increase nationwide.