A New Yorker tucking into a Big Mac at the McDonald's restaurant on 161st Street in the Bronx couldn't order it with any sweetened soda larger than 16 ounces, under a proposed city ban on large sugary drinks.
But that same thirsty customer could walk around the corner to the J&M Grocery and buy a 67-ounce bottle of Coca-Cola.
As public-health officials praised New York City Mayor Michael Bloomberg's proposal to ban the sale of large-size drinks in restaurants and other locations Thursday, some academics and business groups called the plan an ineffective way to handle the obesity crisis and criticized it as government overreach.
Mr. Bloomberg, who led the city's ban on smoking in bars and restaurants nearly a decade ago, wants to prohibit the sale of sugary drinksâ"such as soda, sports drinks, sweetened tea or coffeeâ"in cups or containers that have more than 16 fluid ounces. The ban would affect beverages served at restaurants, mobile food carts, delis and concessions at movie theaters, stadiums and arenas.
But puzzling to many in the city are the exceptions to the ban: It wouldn't pertain to supermarkets, groceries or convenience stores. More specifically, 7-Eleven's "Big Gulp" drink would be safe.
Mr. Bloomberg defended the proposal on Thursday as an effort to take on obesity which he called "a local problem for us," and "to encourage people to live longer."
"If you remember, the smoking ban was very controversial at the beginning," he said. "I don't think the public would stand to go back to the days where you have to breathe other people's smoke."
The city's health department said obesity has led to a surge in the prevalence of type 2 diabetes, which can result in blindness, hypertension and amputations. One in three adult New Yorkers either has diabetes or a condition known as pre-diabetes, the department said.
Corinne Krupp, a professor of public policy at Duke University, described the proposal as "silly."
"I just don't think it's an effective public policy to address obesity," Ms. Krupp said. "It's just going to shift behavior from buying one big soda to buying smaller ones."
Executives in the beverage industry lambasted the mayor and called on the city's residents to voice their disapproval. "New Yorkers expect and deserve better than this," a statement from Coca-Cola Co. said. "They can make their own choices about the beverages they purchase."
The mayor has the power to enact the proposal through the city's Board of Health, over which he has presumed control because he has appointed its members. His potential successors, however, are already raising the possibility of lifting the ban after Mr. Bloomberg leaves office in December 2013. The ban could begin as early as March.
Michael Jacobson, director of the Center for Science in the Public Interest, a Washington group that focuses on nutrition and food safety, lauded the mayor for a "creative step to help stem the obesity epidemic."
"It's really the responsibility of a health department to reduce chronic disease rates," he said. "New York City is saying that's our responsibility and we're going do it."
Public health officials across the country and advocates against obesity have long discussed the dangers of sweetened drinks, but the mayor's proposal is believed to be unprecedented in scope in the U.S.
The mayor's proposal comes after a series of failed efforts by his administration to limit the intake of sugary drinks. Last year, the Obama administration rejected the mayor's request to bar city food-stamp recipients from using their benefits to buy soda and other sugary drinks. In New York, the state legislature has rejected the mayor's call for a soda tax.
Part of the allure of Mr. Bloomberg's new proposal, administration officials concede, is that the mayor doesn't need the approval of a governmental authority outside Mr. Bloomberg's control.
Thomas Farley, commissioner of the city's Department of Health and Mental Hygiene, explained the rationale behind allowing stores to sell tbig, sugary drinks but not restaurants.
"When a restaurant serves you an item, it's meant to be consumed at one sitting," he said. "Whereas when a grocery sells you an item, it's maybe consumed by multiple people across multiple (meals). It makes sense that there would be different rules that apply. It's also true that the Board of Health regulates restaurants but it's the state that regulates grocery stores. So, we don't have the legal authority to do this at the Board of Health".
Karen Congro, director of the Wellness for Life program at the Brooklyn Hospital Center in New York, said she thinks the extensive publicity sparked by the proposal would help inform the public about the dangers of sweetened drinks. But the actual ban, she said, is unlikely to reduce obesity. "Without education, I think, it's limited what can be done with this," she said. "They're just going to buy two smaller drinks."
Brian Wansink, a Cornell University professor who wrote a book on the topic called Mindless Eating, said he received a call Wednesday from City Hall about the proposal. He asked whether the administration had consulted retailers about how they might be able to collaborate on a solution.
"I was a little bit disappointed to see that they hadn't tried to engage retailers to try to figure out a solution that risked less backlash," Mr. Wansink said.
He pointed to ideas that have come out of his research, such as 100-calorie packages of snacks, that food companies have since implemented.
"All of a sudden it's not pushback," said Mr. Wansink, who directs Cornell's Food and Brand Lab. "It's you gave themâ¦win-win idea about how to make money and make people skinnier."
In a McDonald's near Yankee Stadium, Dave Rodriguez, 35 years old, sipped a 32-ounce sweet tea. He said he was torn.
"It has a positive and a negative side to it," he said. "When it comes to health issues with sugary drinks, you can get all types of diseases. The negative would be you're telling them what to do with something they buy."
Ethan Knecht, a 27 year old teacher who lives in Brooklyn, soaked up the sun Thursday afternoon while sipping a sugarless black cherry seltzer.
"I think it's a good idea," he said. "It's a governmental issue. The amount of sugar that corporations are putting in beverages is out of control and the government needs to be able to regulate it."
â"John Letzing, Alison Fox
and Danny Gold
contributed to this article. Write to Michael Howard Saul at michael.saul@wsj.com and Andrew Grossman at andrew.grossman@wsj.com