Kelly Brownell, director of the Rudd Center for food policy and obesity at Yale University, cited research linking increasing portions of sugared beverages -- as well as soup and foods such as macaroni and cheese, sandwiches, pasta, and potato chips -- to a 25-50 percent increase in overall consumption. Worse, he said, liquid calories don't create the same feeling of fullness as solid foods do, so consumers often don't make up for the excess by cutting back at subsequent meals.
People also tend to consume food in the size the bag, a bottle or a box it comes in, a phenomenon known as unit bias. When packaging is larger, people consume more. With the steady growth in package sizing over the last few decades -- especially soda bottles -- this has consumers unconsciously eating more than they intend.
However, many obesity researchers say limiting drink sizes is a useless gesture that gives a false sense of accomplishment.
"It's never been definitively shown that the obesity epidemic is due to drinks larger than 16 ounces," said Nikhil Dhurandhar, an obesity researcher from Pennington Biomedical Research Center in Louisiana. He did not attend the hearings but is familiar with the Bloomberg plan.
He said there is no way to compartmentalize eating and that limiting or removing a single food from the diet is no guarantee it won't be replaced by another source of calories.
"It's like digging a hole in water. If you take away one thing, it's likely to be replaced."
Indeed, studies by the Centers for Disease Control have not indicated a definitive link between soda consumption and obesity. And a recent study published in the Journal of Behavior Nutrition and Physical Activity found that when schools eliminated unhealthy foods and beverages from campus, children did make healthier choices -- but obesity rates didn't decline and were no different from schools without such bans.
Regardless of where they stood on the issue, just about everyone who attended the hearing conceded that Bloomberg's proposal was likely to pass when it comes up for vote this September by a panel of health experts handpicked by the mayor himself. If the rule is adopted, it will go into effect in March 2013. Establishments that violate size limits can be fined by up to $200 per violation.
In addition to the public health policy experts represented at the meeting, a slew of celebrities, including chef Jamie Oliver, filmmaker Spike Lee, and former president Bill Clinton have publically supported the Bloomberg initiative.
Still, some said the ban could be a slippery slope.
"What will they be telling me next," councilman Halloran wondered. "What time I should go to bed? How many potato chips I can eat? How big my steak should be?"