New York City's Board of Health has voted to ban artery-clogging trans-fats from the city's restaurants.
Trans-fats are in many fried and baked foods
The city's health officials have for years warned that the fats can cause obesity and lead to heart disease.
Trans-fats go into partially hydrogenated vegetable oil, which is commonly used for frying and baking.
The unanimous vote makes the city the first in the US to ban the fats, although the original strict deadline to comply has been lengthened.
Restaurants will be banned from using most frying oils containing trans-fats from 1 July, and will have to eliminate the fats from all foods by 1 July 2008.
Trans-fats are made when food processors harden fat to make it more like butter.
It can then be used for frying or baking, or put into processed foods and ready-made mixes for cakes and drinks like hot chocolate.
The Food and Drug Administration estimates that on average, Americans eat 4.7lb (2.14kg) of trans-fats each year.
The move has met with opposition from 24,000 restaurant owners in the city, who said the original six-month deadline to replace cooking oils and fats was unrealistic.
New York Mayor Michael Bloomberg has defended the move.
They are partially hydrogenated vegetable oils, turning oily foods into semi-solid foods
Used to extend shelf life of products
Put into pastries, cakes, margarine and some fast foods
Can raise levels of "bad" cholesterol
Even a small reduction in consumption can cut heart disease
They have no nutritional benefit
"Nobody wants to take away your French fries and hamburgers - I love those things too.
"But if you can make them with something that is less damaging to your health, we should do that."
For more than a year, there has been a voluntary programme for the city's restaurants and fast food outlets to remove trans-fats from the food they serve.
Many American food makers and restaurant chains, including McDonald's and Taco Bell, have been experimenting with replacements for oils and foods that contain trans-fats.
Chicago is also considering a law that would restrict use of trans-fats in large restaurants.