(CNN) -- New York City Mayor Michael Bloomberg's proposed ban on the sale of large-size sodas and other sugary beverages moved forward Tuesday after the city's Board of Health unanimously voted to open the plan to a three-month public comment process.
The ban would outlaw such drinks larger than 16 ounces at restaurants, food carts and any other establishments that receive letter grades for food service. It would not apply to grocery stores.
"The Board of Health is a group of independent health experts ... they were reviewing this for the first time today, and then this is a public comment process. We think that this is a good process," Health Commissioner Dr. Thomas Farley said in a news conference Tuesday.
"Obviously, me as the health commissioner, I am supportive of this rule, but the board is the one that makes the ultimate decision," Farley said.
The board members, who are appointed by the mayor, will formally vote on the proposal in September, officials said.
"If approved, the city's proposal would take effect six months after Board of Health approval and would be enforced by the city's regular restaurant inspection team," a statement from Bloomberg's office said last month. "Restaurant owners will have nine months from the adoption of the proposal until they face fines."
Fines will then be $200, the statement said.
After Bloomberg announced the initiative last month, critics -- including McDonald's and Coca-Cola, which stand to be hurt by the proposal -- quickly assailed it as "misguided" and "arbitrary."
Speaking by satellite to the All Things D technology event in California last month, Bloomberg said, "This is something we think we have the legal authority to do. We¹re not taking away anybody's right to do something; we're simply making it different for them in how they do it." He said he hoped the move will help lead to different behaviors.
The city spends $4 billion a year on medical care for overweight people, he said.
The statement from his office cited health problems facing the city, including an increase in obesity. "The single largest driver of these alarming increases in obesity is sugary drinks, which have grown in size," the statement said.
It was not immediately clear what that assertion was based on.
While the consumption of sugary drinks contributes to obesity, the Centers for Disease Control and Prevention does not name a single largest cause nationally.
In a report in May, the nonprofit Institute of Medicine said, despite the "difficulty of quantifying relative contributions to the obesity epidemic, researchers have found strong associations between intake of sugar-sweetened beverages and weight gain. Although the exact mechanisms of how sugar-sweetened beverages contribute to obesity are not fully known, their link to obesity is stronger than that observed for any other food or beverage."
McDonald's restaurants issued a statement saying, "Public health issues cannot be effectively addressed through a narrowly focused and misguided ban. This is a complex topic, and one that requires a more collaborative and comprehensive approach."
A statement from the Coca-Cola company said the "people of New York City are much smarter than the New York City Health Department believes. ... New Yorkers expect and deserve better than this. They can make their own choices about the beverages they purchase. We hope New Yorkers loudly voice their disapproval about this arbitrary mandate."
Broad public health initiatives have become a hallmark of Bloomberg's administration. Under the mayor, the city has banned trans fats from restaurants, smoking from parks and has placed graphic ads targeting junk food and tobacco in public transit.
CNN's Ronni Berke, Mark Norman, Mary Snow, and Kristen Hamill contributed to this report.