In a first of its kind move among major US cities, New York has banned trans-fats in restaurants.

The move took full effect this week and follows the city's 2003 ban on public smoking.

Artificial trans-fats give french fries their crunch and pie crusts their flakiness and chefs have been figuring out how it was done before trans-fats came into wide use during World War II, when margarine became a substitute for rationed butter and Crisco became a staple in US kitchens.

Artificial trans-fats, which also are known as partially hydrogenated vegetable oil, have just as many calories as other fats but clog arteries in the same way that saturated fats like butter and lard do.

A year ago, New York restaurants were banned from using the artery-clogging fats in cooking oils and spreads. On Tuesday, all trans-fat products were banned, although the city will allow a grace period before issuing fines up to $2,000.

Laura Stanley, a former senior editor for Martha Stewart Living Omnimedia who heads the city's Trans-Fat Help Center, a clinic to help restaurants make the transition, said there had been complaints from bakeries and restaurants about trans-fat-free cookies turning out too crisp. It was nothing that could not be fixed with a little adjustment in baking time, she said.

"I don't want to be cavalier and say that it's solved. But I'm really, really optimistic," said Stanley, who has led a series of seminars to educate cooks about trans-fats and posted tips on a city Web site, Notransfatnyc.org.

Dunkin' Donuts, Burger King, and McDonalds Corp., as well as KFC and Pizza Hut, which are both owned by Yum! Brands Inc., all say that they have eliminated trans-fats from their New York restaurants, and they are on track to do the same across the country.-Reuters