HOUSTON -

Five years after New York City banned trans fats in all its 24,000 restaurants, a new study shows the ban had a positive effect on its residents.

"After the restriction of trans fat in NYC, we looked at what the average amount of trans fat was in lunchtime purchases at fast food restaurants, and we found that trans fat went down," said Christine Curtis with the NYC Department of Health and Mental Hygiene.

Trans fats are found in fried foods and baked goods made from shortening or margarine. They are known to increase the risk of heart problems and lead to weight gain.

In a new study, New York City health officials calculated the nutrition content of nearly 7,000 receipts from orders placed after the ban was implemented. They found diners ate significantly less trans fat and there was only a slight increase in saturated fat.

"You can walk into your favorite restaurant, order the exact same lunch you've always ordered, and it just has much less trans fat, nothing else has changed," said Curtis.

Researchers believe a customer's risk of heart disease has changed.

"We know that when trans fat intake goes down, bad cholesterol goes down, cardiovascular disease risk goes down," said Curtis.

Experts say consumers still need to make healthy decisions when dining out, like limiting saturated fat and eating plenty of fruits and vegetables.

Since the New York ban took effect, other cities, including Philadelphia, Boston, and Seattle, have followed suit. California also has a ban on trans fats.