Products free of trans fat are rapidly appearing in supermarkets snack aisles, but the fried chicken and french fries to go usually are cooked in shortening or oil containing trans fat.
"Unfortunately, the restaurant industry has almost become addicted to them because it's sort of the cheap and easy thing to do," said Dr. Walter Willett, a Harvard University nutrition expert. "There now are alternatives that are available, and restaurants just need to take their customers' health to heart."
The government started telling people in January to eat as little trans fat as possible. Studies have linked it to higher risk of heart attacks. It also has been shown to raise bad cholesterol and, unlike saturated fat, reduce good cholesterol.
To find trans fat, look for the word "hydrogenated" in the list of ingredients on a food label. Hydrogenation is the process of turning liquid vegetable oils into hardened fats — think shortening or margarine.
Harder fats give pie crust and other baked goods their delectable texture. These fats also are durable. They stand up to high temperatures and last long enough to fry multiple batches of fries, chicken, fish and onion rings.
Beginning next year, trans fat must be listed on food labels, helping shoppers who have had to hunt through the ingredients. The labeling requirement has driven the development of trans fat-free cookies, crackers, chips and other foods.
For restaurants, which provide one in every five meals in the country, there is no such requirement. Restaurants are only now beginning to take trans fat off their menus.
"They're in places where you wouldn't expect to find them, like in oyster crackers. We went through a ton of oyster crackers," said Roger Berkowitz, president and chief executive of Legal Sea Foods.
An East Coast chain of 30 restaurants, Legal Sea Foods has eliminated trans fat from its menu, switching to a trans fat-free vegetable oil and finding a manufacturer that precooks french fries without using trans fats.
Fries present one of the toughest challenges. They usually arrive at restaurants blanched, or precooked, in oil with trans fats. So even if a restaurant has switched to a healthier oil, french fries can still have trans fat. But manufacturers are starting to offer trans fat-free fries.
The Ruby Tuesday's chain is asking its suppliers to remove trans fat and has switched from hydrogenated soybean oil to trans fat-free canola in its more than 700 restaurants, spokesman Perrin Anderson said.
Making the switch is not cheap. Yet it is not terribly expensive, either, said Kelly Brintle, senior vice president at food service supplier Ventura Foods of Brea, Calif., which sells a trans-fat free oil.
The switch probably adds a penny to the cost of an individual order of french fries, Brintle said.
"It's a matter of us getting the operator out of the mentality of expecting always just the lowest cost," he said.
Some believe the government did not go far enough on trans fat in the dietary guidelines made public last month.
The Washington-based Center for Science and the Public Interest has petitioned the Food and Drug Administration to require restaurants to disclose their use of trans fat.
Doctors and scientists who developed the recommendations for the dietary guidelines set a specific trans fat limit: People should consume 1 percent or less of their calorie intake.
But when the Agriculture and Health and Human Services departments issued the guidelines, they changed that to keeping consumption "as low as possible."
"I think their feeling probably was that it would be hard to do it right away. They want trans fat to be dropped, but they want to give food companies, particularly baked goods companies, time to switch this around, get the level down below 1 percent," said Dr. Xavier Pi-Sunyer, a members of the guidelines panel who directs obesity research at St. Luke's-Roosevelt Hospital in New York.
Until restaurants eliminate trans fat from their food, another doctor on the panel offered these suggestions: "Don't order deep-fried foods. Order things like broiled fish, chicken breast, lean red meat," said Dr. Penny Kris-Etherton, a nutritionist.
That's a tall order considering the public's tastes.
The fastest-growing restaurant food last year, according to Harry Balzer of the consumer research firm NPD Group, was fried chicken.