PLANO, Texas — Frito-Lay Inc., whose chips are frequently a target for nutritionists, said Tuesday it would eliminate an especially harmful type of fat from its products and offer more reduced-fat snacks.

Fast-food and snack makers have come under increasing pressure to help reverse a trend toward more obesity, especially among American children. By early next year, Frito-Lay said it will switch from hydrogenated oils containing trans fatty acids to corn oil in cooking some of its most popular salty chips such as Doritos, Tostitos and Cheetos.

The company will also roll out reduced-fat versions of its Lay's potato chips and Cheetos in the next few months, joining lighter products such as its Baked Lay's and Baked Tostitos chips.

Frito-Lay is also developing products such as broccoli-flecked chips to appeal to health-conscious consumers, officials said.

Abelardo Bru, chief executive of Frito-Lay North America, said that Frito-Lay is "working to be part of the solution to the obesity problem." He said sales of healthier snacks are growing 20 per cent per year.

Frito-Lay, based in Plano, is a subsidiary of PepsiCo Inc. and accounts for about two-thirds of the Purchase, N.Y.-based parent's profits.

One group that has been critical of the food industry, the Washington-based Center for Science in the Public Interest, applauded Frito-Lay's announcement but said it would do little to encourage American youngsters to eat a balanced, healthy diet.

"It's a good step, but they're still contributing to snacking on junk food instead of snacking on fruit or something that's healthful," said the group's director, Michael F. Jacobson.

Jacobson predicted, however, that Frito-Lay's announcement would prompt other food makers to remove trans fats from their products.

Trans fats are produced through a chemical process in which hydrogen is added to unsaturated fatty acids to create a solid or malleable fat with a longer shelf life. Some research has linked trans fats to a greater risk of heart disease.

Frito-Lay said it already makes Lay's and Ruffles chips without trans fat. This month, McDonald's announced that its fast-food restaurants would cook french fries in oil with less trans fat.

Frito-Lay has signed up a prominent Dallas health and fitness advocate, Dr. Kenneth Cooper, to help promote its products and advise it on nutrition matters. The company said 10-ounce packages of its reduced-fat Lay's chips will soon feature nutrition tips from Cooper.

Cooper declined to reveal how much Frito-Lay is paying him for consulting and how much it is contributing to his aerobics institute and his syndicated radio show.

In afternoon trading, shares of PepsiCo fell 40 cents to $36.80 on the New York Stock Exchange.