No more trans fats with those french fries? No problem.

The city's ballyhooed ban on trans fat cooking oils in all New York restaurants — an idea that gave chefs indigestion when first proposed — seems to be going surprisingly smoothly. Across the city, most fast food chains say they've already made the switch days before the July 1 deadline, which is Sunday.

The same cannot be said for a second restaurant rule taking effect then: the posting of calories on fast-food menus. The major chains are defying that regulation and hope a lawsuit will overturn it.

The city doesn't plan to fine anyone for violating either rule until Oct. 1.

Still, the trans fat overhaul is viewed as a major victory by health advocates. Trans fats, found in partially hydrogenated vegetable oils, clog arteries and contribute to heart disease. But they are also cheaper and have a longer shelf life, so industry at first stubbornly resisted dumping them.

That began to change last winter.

Cooking oil companies had already ramped up production of trans-fat alternatives. Restaurant supply companies began stocking kitchens with replacement products.

Big fast food chains that relied heavily on the old oils, from Burger King to Carl's Jr. to Kentucky Fried Chicken, announced they would eliminate the stuff from their fryers nationwide.

Even McDonald's, which had anguished over the potential impact on its french fries, said its phase-in of the new oils in thousands of restaurants has gone unnoticed by customers.

"The transition has been absolutely seamless," said spokesman Walt Riker.

While the city health department hasn't finished tallying results of a recent survey on oil use, there is evidence that smaller restaurants are ready too.

A special help line, set up by the city for chefs trying to reform their kitchens, has been lightly used.

The ease of the switch to zero-trans oils may have been aided by the behind-the-scenes work of seed and oil companies.

David Dzisiak, a cooking oils specialist at Dow AgroSciences, said the company began investing research dollars in zero-trans fat Omega-9 canola and sunflower oils back when the very first studies suggested the oils were unhealthy.

"We started on this 10 years ago," he said. "We now have the capacity to supply over a billion pounds of this oil."

Resistance to the ban still exists, but it may be primarily on philosophical grounds.

Mat Arnfield, the chef at A Salt & Battery, a much-loved Manhattan fish and chips shop, said any cooks still complaining about the change aren't concerned with taste.

The primary difference between the trans-fat oils and their alternatives, he said, is cost. The blend of corn and canola oils he uses in his frying bins now is slightly more expensive than the partially hydrogenated vegetable oils rich in trans fats, but the price difference is small.

"If they are cutting corners that much," he said of restaurants reluctant to switch, "I wouldn't really trust those guys to make me a plate of food anyway."

Restaurants in the city had never kicked too hard over taste considerations, but they had chafed at the idea that anyone should be telling them how to cook.

And there is still some question about whether the ingredients restaurants are using instead of trans fats are just as bad for you. Restaurants can comply by switching to a cooking oil high in saturated fat, which could clog your arteries almost as quickly.

The tougher transition on trans fats could come a year from now, when the city has ordered artificial trans fats out of all products, not just oils and spreads.

Experts say it may be more difficult to find a good replacement for partially hydrogenated vegetable shortenings, which give baked goods like cookies and crackers their characteristic texture.

"That is definitely a more challenging environment," said Bill McCullough, a marketing director for St. Louis-based Bunge Oils.

Alternatives are available, he said, but culinary researchers are still at work on something that will have the taste and texture of butter or lard and the shelf life of a hydrogenated product high in trans fats.

"We realize as an organization that it is just a matter a time before hydrogenation is gone," he said. Bunge has already stopped marketing products containing artificial trans fats, McCullough said.

"We decided it would be like marketing Marlboro Red cigarettes."