Thousands of city eateries may have to revise their recipes for French fries, doughnuts, cookies, and other baked goods under a proposal by the Bloomberg administration to ban the use of trans fats in all restaurants across the five boroughs.

The city wants to force restaurants to remove the artery-clogging acids within two years as part of the administration’s most aggressive health policy push since it banned smoking in bars and restaurants three years ago. A separate proposal would require many fast-food chains to prominently display calorie information on menus and menu boards.

City officials made the proposals yesterday to the independent Board of Health, which is likely to approve the new rules by the end of the year after a public comment period.

Trans fat “is a dangerous and unnecessary ingredient,” the city’s health commissioner, Dr.Thomas Frieden, said yesterday in announcing the proposal. “Trans fat is replaceable, and nobody will miss it when it’s gone.”

The Department of Health and Mental Hygiene is pushing for a ban after a year-long campaign urging the city’s more than 24,000 restaurants to eliminate trans fat voluntarily. As part of the education push, officials conducted extensive nutrition training and sent health bulletins to thousands of restaurants.

The effort simply didn’t work, Dr. Frieden said. About half of the restaurants used the artificial substance in oils and spreads before the campaign, and the percentage was virtually unchanged a year later.

No major American city has banned trans fat from restaurants, although Chicago is considering limiting its use. In 2003, Denmark became the first country to enact laws restricting the sale of foods containing the fatty ingredient.

Some experts say trans fat contributes to the deaths of more than 500 New Yorkers each year. High-calorie foods can lead to obesity and diabetes, which have long been on the rise, Dr. Frieden said.

The initiatives drew immediate praise from health advocates, who called the proposed trans fat ban a bold step in combating heart disease, which they said kills 18,000 city residents under the age of 65 each year.

The president of the New York Academy of Medicine, Dr. Jeremiah Barondess, said the regulations “represent an extraordinarily important effort on behalf of the health of every New Yorker.” He added: “Reducing the levels of trans fat in our diet and ultimately phasing them out is a key step in protecting cardiovascular health.”

The proposals faced stiff opposition from a top industry group and others who criticized the move as yet another example of the Bloomberg administration imposing its social mores on the public.

“When is Nurse Bloomberg planning to let us fill up our own plates?” a senior fellow at the Manhattan Institute, Walter Olson, said. Saying that the mayor was treating New Yorkers “like tiny, tiny children,” he called the proposed trans fat ban a “gross infringement on the rights of restaurants and customers to cut their own deals.”

The executive vice president of the New York State Restaurant Association, Charles Hunt, said the restrictions would cause problems for many small restaurants in the city that must find alternatives to partially hydrogenated vegetable oils and many margarines and shortenings containing artificial trans fat.

“We’re not happy about it,” Mr. Hunt said. “We don’t feel it’s within the purview of a nonelected agency to impose a ban on the food industry.”

The use of trans fat, he said, “should be up to the restaurants and the customers to decide, not the government.”

In a carefully choreographed announcement yesterday, the health department sought to emphasize both the danger of trans fat and the ease with which restaurants can switch to alternative ingredients.

Dr. Frieden stood next to a handful of nutrition scholars, cardiologists, and restaurant executives whose chefs have already eliminated trans fat from their recipes. Large posters displayed charts and a close-up photograph of a clogged artery. Officials set up one table with vegetable and natural oils and another containing two platefuls of shortening that Dr. Frieden said represented the amount of trans fat an average New Yorker consumed in a year. (The shortening was not labeled, but a department spokesman said it was the same as Crisco.)

A spokeswoman for Crisco, Tina Neer, said sales to restaurants make up a minimal portion of the company’s business and that the company also offered a version with zero grams of trans fat.

The city offered no estimates of how much it would cost the restaurant industry to remove all trans fats, but Dr. Frieden said compliance would not affect an eatery’s bottom line, as alternatives to trans fats were available at the same price. Under the proposal, restaurants would have to switch to oils, margarines, and shortening that have less than half a gram of trans fat in each serving within six months. In 18 months, all other items would have to be trans fat-free.

Owners and chefs at several prominent restaurants and bakeries said they either did not use trans fat or had already switched to other oils and spreads. The corporate executive chef of B.R. Guest Restaurants, Christopher Giarraputo, said the company began using trans fat-free oils years ago. It discovered last year that a few other of its ingredients, such as peanut butter, contained trans fat, and it changed brands last year.

The owner and chef of Toqueville restaurant, Marco Moreira, said he has always avoided ingredients that contain trans fat, especially margarine. “Nothing beats the quality and taste and texture of butter,” he said.

The proposal to require the display of calorie information on menus and menu boards apply to the many chains, such as McDonalds and Wendy’s, that already make those details publicly available, either in printed brochures or online. Those eateries account for only about 10% of the city’s restaurants. City officials contend those methods have little value, because the information is too hard to find.

Restaurants that don’t offer that information now will not have to comply. “It is not feasible, nor do we have any plans to require this for other restaurants,” Dr. Frieden said.

Several major chains reacted hesitantly to the proposal. The vice president of corporate communications for McDonalds, Walt Riker, noted in a statement that the company provided nutritional information at its restaurants and on its Web site, although it is not displayed on menu boards. “Concerning trans fats, McDonald’s knows this is an important issue which is why we continue to test in earnest to find ways to further reduce levels,” Mr. Riker said. “We will closely examine the board’s proposal.”

Dunkin Donuts said it would also look at the proposal, while Krispy Kreme issued a statement saying it was “very proud” of its signature “Hot Original Glaze” doughnuts, which contain 200 calories and contain trans fat.

Many New Yorkers said they welcomed the new restrictions. “It’s a great idea,” Donald Willians, 42, said while eating at a Popeye’s in Lower Manhattan. “Anything you put in your body, they should tell you what’s in it. This should’ve happened a long time ago.”