How many calories are in that Big Apple?

NEW YORK — From $2 dim sum to $150 foie-gras-and-truffle burgers, New York is a city that always eats -- and often out.

But lately, the restaurant table has become a battleground.

New city rules require chain restaurants to display calorie counts on menus. A restaurant lobbying group sued in federal court in January to prevent the city from enforcing the requirement, which is due to take effect at the end of this month.

Proponents of the calorie disclosure say the measure will help diners make informed choices. More than half of the city's adult population is overweight, and the city's number of diabetes cases has doubled over the last decade.

Opponents say that restaurants are willing to provide the information but that it's a costly one-size-fits-all regulation. Smaller chains that change their menus often will be hit especially hard, they say.

Though the regulations apply only to chains with at least 15 locations nationwide -- about 10% of the city's restaurants -- the New York State Restaurant Assn. is concerned that the rules will be extended to every city restaurant.

"The camel puts his nose in the tent and the next thing you know, he's in the tent," said Executive Vice President Chuck Hunt.

Chain restaurants are the focus, health officials say, because they tend to offer high-calorie dishes and large portions. And chains' standardization means the rules will be easier to enforce, they say. Similar legislation has been passed in Seattle and San Francisco and is pending in many cities and states. In California, Gov. Arnold Schwarzenegger vetoed a food-labeling bill last year that had been heavily opposed by the California Restaurant Assn.

Mayor Michael R. Bloomberg, a hot dog aficionado, has made improving New Yorkers' health a priority. Last week, he introduced the Green Carts program, which aims to bring more produce vendors to poorer neighborhoods.

Five years ago, the city pushed through a smoking ban in bars and eateries despite loud resistance. Officials then set their sights on artificial trans fats, voting in 2006 to ban the artery-clogging frying oils.

Last year, a judge struck down the city's first effort to mandate nutritional information on menus. After the Board of Health revived the measure, the New York State Restaurant Assn. sued. A judge is considering the matter.