From the corner pizzeria to high-end bakeries, New York City's world famous eateries are preparing for kitchen scrutiny as the board of health moves Tuesday to ban trans fats.

The board was poised on Tuesday to make New York the nation's first city to outlaw the unhealthy oils, though it's expected to give restaurants a slight break by relaxing what had been considered a tight deadline for compliance.

The restaurant industry argued that it was unrealistic to give eateries six months to replace cooking oils and shortening and 18 months to phase out the ingredients altogether.

"We hope that the board of health will have significantly changed the original proposal, taking into consideration the concerns raised by 24,000 restaurateurs in New York City," said Sue Hensley, spokeswoman for the National Restaurant Association.

Trans fats are believed to be harmful because they contribute to heart disease by raising bad cholesterol and lowering good cholesterol at the same time. Some experts say that makes trans fats worse than saturated fats.

A common form of trans fats is partially-hydrogenated vegetable oil, which is used for frying and baking and also turns up in processed foods like cookies, pizza dough and crackers. Trans fats, which are favored because of their long shelf life, are also found in pre-made blends like pancake and hot chocolate mix.

The FDA estimates the average American eats 4.7 pounds of trans fats each year.

Mayor Michael Bloomberg, who banned smoking in bars and restaurants during his first term, has dismissed cries that New York is crossing a line by trying to legislate diets.

"Nobody wants to take away your French fries and hamburgers — I love those things too," he said recently. "But if you can make them with something that is less damaging to your health, we should do that."

Many food makers have stopped using trans fats on their own, after the U.S. Food and Drug Administration began requiring companies to list trans fat content on labels.

Fast-food restaurants and other major chains are particularly interested in the board's decision on Tuesday because a trans-fat ban wouldn't just involve substituting one ingredient for another. In addition to overhauling recipes, they would have to disrupt nationwide supply operations and try to convince customers that the new French fries and doughnuts will taste just as good as the originals.

McDonald's Corp. has been quietly experimenting with more than a dozen healthier oil blends in some of its U.S. restaurants, but still has not committed to a full switch. At an investor conference last month, CEO Jim Skinner said the company is making "very good progress," at developing an alternative, and vowed to be ready for a New York City ban.

Wendy's International Inc. introduced a zero-trans fat oil in August and Yum Brands Inc.'s KFC and Taco Bell said they too will cut the trans fats from their kitchens.

Taco Bell worked for more than two years to find a substitute, conducting blind consumer taste tests and extensive research, the company said.

Chicago is also considering its own trans fat law, which wouldn't ban them outright but would severely restrict the amount that kitchens can use. The measure would apply only to large restaurants, defined as those that make more than $20 million in sales per year.

New York's move to ban trans fats has mostly been applauded by health and medical groups, although the American Heart Association warns that if restaurants aren't given ample time to make the switch, they could end up reverting to ingredients high in saturated fat, like palm oil.