Seeking to reduce runaway obesity rates, the New York City Board of Health on Thursday approved a ban on the sale of large sodas and other sugary drinks at restaurants, street carts and movie theaters, the first restriction of its kind in the country.

The measure, championed by Mayor Michael R. Bloomberg, is certain to intensify a growing national debate about soft drinks and obesity, and it could spur other cities to follow suit, even as many New Yorkers say they remain uneasy about the plan.

“This is the single biggest step any city, I think, has ever taken to curb obesity,” Mr. Bloomberg said shortly after the vote. “It’s certainly not the last step that lots of cities are going to take, and we believe that it will help save lives.”

The measure, which bars the sale of many sweetened drinks in containers larger than 16 ounces, is to take effect on March 12, unless it is blocked by a judge. The vote by the Board of Health was the only regulatory approval needed to make the ban binding in the city, but the American soft-drink industry has campaigned strongly against the measure and vowed this week to fight it through other means, possibly in the courts.

“This is not the end,” Eliot Hoff, a spokesman for New Yorkers for Beverage Choices, a group financed by the soft-drink industry, which opposes the restrictions, said in an e-mail moments after the vote.

“By imposing this ban, the board has shown no regard for public opinion or the consequences to businesses in the city,” Mr. Hoff wrote, noting a recent poll that showed 60 percent of New Yorkers believed the plan was a bad idea.

Mr. Bloomberg is known for introducing ambitious — and, some say, overreaching — public health policies, like bans on smoking in bars and city parks and the posting of calorie counts on menus in chain restaurants; they often catch on around the country.

Curbing obesity has been the latest goal of the mayor, who has been concerned about high rates of diabetes and weight-related health issues. More than half of adult New Yorkers are obese or overweight, according to the city’s health department, which said it believed 5,000 New Yorkers died every year as a result of health problems related to obesity.

Critics of the mayor’s proposal — including some City Council members and a mayoral contender, the former city comptroller, William C. Thompson — said the measure could lead to small businesses losing money on sales. An advertising campaign by the soda industry, which has so far cost more than $1 million, stressed that the policy would restrict consumers’ freedom to buy beverages as they see fit.

But those positions were rejected on Thursday by the board, which voted 8 to 0, with one abstention, to approve the measure. (The board has 11 members, all appointed by Mr. Bloomberg. One was absent from Thursday’s hearing and another retired from the board this summer and has not yet been replaced.)

“I can’t imagine the board not acting on another problem that is killing 5,000 people per year,” said Dr. Joel A. Forman, a board member and professor at Mount Sinai School of Medicine, before voting in favor of the proposal. “The evidence strongly supports a relationship between sweet drinks and obesity.”

Dr. Deepthiman K. Gowda, a professor of medicine at Columbia University and a member of the Board of Health, said he recognized that the public had concerns about the plan. But, he said, he had seen firsthand the deadly effect of obesity on patients he has treated in the city.

“The same way that we’ve become acclimatized and normalized to sodas that are 32 ounces, we’ve started to become acclimatized to the prevalence of obesity in our society,” Dr. Gowda said. “The reality is, we are in a crisis, and I think we have to act on this.”

The member who abstained, Sixto R. Caro, is a former president of the Spanish American Medical Dental Society of New York who was appointed by Mr. Bloomberg in 2002. He expressed concern that the plan did not do enough to lower obesity rates, and said the city should take a more holistic approach.

Only establishments that receive inspection grades from the health department, including movie theaters and stadium concession stands, will be subject to the rules. Convenience stores, including 7-Eleven and its king-size Big Gulp drinks, would be exempt, along with vending machines and some newsstands.

The restrictions would not affect fruit juices, dairy-based drinks like milkshakes, or alcoholic beverages; no-calorie diet sodas would not be affected, but establishments with self-service drink fountains, like many fast-food restaurants, would not be allowed to stock cups larger than 16 ounces.

At a news conference on Thursday, Mr. Bloomberg announced that the Barclays Center, the new basketball arena in Brooklyn that is to open next week, would immediately begin complying with the new rules and offer sugary drinks only in containers of 16 ounces or less.

Asked about the soda industry’s well-financed campaign against his plan, Mr. Bloomberg responded with an amused look.

“I just spent roughly $600 million of my own money to try to stop the scourge of tobacco,” the mayor said, as a round of laughter began to rise in the room. “I’m looking for another cause. How much were they spending again?”