So more than a few New Yorkers took it especially hard Thursday when they learned that Mayor Michael R. Bloomberg wanted to take away their plus-size sodas in restaurants, movie theaters, stadiums, arenas and mobile food carts, as a way, he said, of fighting obesity. …

At least two candidates for next year’s mayoral race also came out against the proposal Thursday, to varying degrees. Christine C. Quinn, the City Council speaker, said that by limiting personal choice, rather than promoting knowledge, “It seems to me to be more on the punitive side of things.” And William C. Thompson Jr., the former city comptroller who lost to Mr. Bloomberg in 2009, released a statement saying, “This move does nothing to teach people about positive nutritional values and sounds more like parlor talk than real solutions for the obesity epidemic.”

But Dr. Wansink said Thursday that as a professor of consumer behavior, and as one of the originators of the 100-calorie snack pack, he believed the mayor’s idea was too confrontational. He said he had warned against it when City Hall consulted him on Wednesday and suggested something along the lines of teaming up with retailers to promote large diet drinks.