No other U.S. city has gone so far as to restrict portion sizes at restaurants to fight weight gain.
Mayor Michael Bloomberg rejected suggestions that the rule constitutes an assault on personal liberty.
"Nobody is banning anything," he said, noting that restaurant customers can still buy as much soda as they want, as long as they are willing to carry it in multiple containers.
He said the inconvenience is well worth the potential public health benefit, and likened the city's actions to measures taken decades ago to phase out lead in household paint.
"We cannot continue to have our kids come down with diabetes at age 6," he said.
Others, though, likened the ban to Prohibition. A New York Times poll last month showed that six in 10 New Yorkers opposed the restrictions.
"It's a slippery slope. When does it stop? What comes next?" said Sebastian Lopez, a college student from Queens. He added: "This is my life. I should be able to do what I want."
The restrictions do not apply to supermarkets or most convenience stores, because such establishments are not subject to Board of Health regulation. And there are exceptions for beverages made mostly of milk or unsweetened fruit juice.
(Because convenience stores are exempt, the rules don't even apply to 7-Eleven's Big Gulp, even though the belly-busting serving of soda has become Exhibit A in the debate over Americans' eating habits.)
Some health experts said it isn't clear whether the ban will have any effect on obesity. But they said it might help usher in a change in attitude toward overeating, in the same way that many Americans have come to regard smoking as inconsiderate.
The regulations follow other ambitious health moves on Bloomberg's watch, many of which were attacked as a push toward a "nanny state."
Yet some have proved to be national trendsetters, such as making chain restaurants post calories on their menus. The city has also barred artificial trans fats in french fries and other restaurant food, cracked down on smoking and promoted breast-feeding over formula.
The Board of Health approved the big-soda ban 8-0, with one member, Dr. Sixto R. Caro, abstaining. Caro, a doctor of internal medicine, said the plan wasn't comprehensive enough.
Others spoke forcefully of the need for action to deal with an obesity crisis.
"I feel to not act would really be criminal," said board member Susan Klitzman, director of the Urban Public Health Program at Hunter College. City Health Commissioner Dr. Thomas Farley called the rule "a historic step to address a major health problem of our time."
The restaurant and beverage industries complained that the city is exaggerating the role sugary beverages have played in making Americans fat.
"This is a political solution and not a health solution," said Eliot Hoff, a spokesman for an industry-sponsored group called New Yorkers for Beverage Choices, which claims to have gathered more than 250,000 signatures on petitions against the plan.
He said the group is considering suing to block the rule.
"We will continue to voice our opposition to this ban and fight for the right of New Yorkers to make their own choices. And we will stand with the business owners who will be hurt by these arbitrary limitations," Hoff said in a statement.
Barring court intervention, enforcement will be carried out by New York City's restaurant inspectors. Violations will carry a $200 fine.
Complying might prove complicated for some establishments.
Starbucks is trying to figure out whether the regulations bar it from selling calorie-packed Frappuccinos in the 24-ounce size.
Another issue could be iced coffee, which many cafes sweeten with liquefied sugar. Customers might have to add the sweetener themselves.
Fast-food restaurants with self-serve soda fountains will be prohibited from giving out cups larger than 16 ounces, but people will still be allowed refills.
Manhattan pizza shop owner Vinnie Siena said halting sales of large sodas will hurt his already thin profit margin, unless he raises prices.
"I'm having a tough time as it is. They don't want the little guy to survive, it seems," he said.
Sugary drink rules, exceptions
What's banned • Sweetened drinks in containers larger than 16 ounces. A range of popular sweetened beverages, including energy drinks, presweetened ice teas and common brands of nondiet soda will be affected.
Exceptions • Beverages that are less than 25 calories per 8 ounces, more than 50 percent milk or 100 percent fruit or vegetable juice.
Cup size • Cafeterias and fast-food restaurants with self-serve soda fountains will be prohibited from giving out cups larger than 16 ounces, but people will still be allowed to refill their cup multiple times.
Who's affected • Only establishments that receive inspection grades from the health department would have to obey the rules, a group that includes movie theaters and stadium concession stands. Convenience stores, including 7-Eleven and its king-size "Big Gulp" drinks, would be exempt, along with vending machines and some newsstands.
In question • Iced coffee may be problematic. Many cafes now sweeten the beverage with liquefied sugar before handing it over to the customer, often in a giant cup.
Enforcement • Will be carried out by New York City's army of restaurant inspectors. Violations uncovered during those inspections will lead to a $200 fine.
The Associated Press