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 its 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.
Associated Press Writer Alex Katz contributed to this report.
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.