DALLAS -- Dr. Sarah Blumenschein sees a pattern in the overweight children who come to her clinic: They snack more often and they eat out more often -- especially at fast-food restaurants.

"The kids don't realize the high calorie and fat levels in fast food," said Blumenschein, a pediatric cardiologist at the University of Texas Southwestern Medical Center at Dallas. "The marketing of fast food has been very clever."

She applauds the recent announcements by McDonald's Corp. and Frito-Lay Inc. that they will reduce a particular form of fat in making french fries and chips.

But she and other medical experts said the move was overdue, and they plan to keep pressing the U.S. food industry to do more to reduce fat, not just substitute one for another.

"Trans fat is a no-brainer. They should have done this a long time ago. We've known about trans fat for 30 years," said Marion Nestle, a professor of nutrition at New York University and author of "Food Politics," a critical look at the food industry's influence.

McDonald's says its fried foods will contain half as much trans fatty acids as before, while Frito-Lay plans by early next year to switch cooking oils to eliminate trans fats, which have been linked to elevated levels of bad cholesterol and a higher risk of heart disease.

Follow the leaders

Nestle expects other food companies to follow the lead of McDonald's and Frito-Lay because of a proposal by the Food and Drug Administration to require warning labels on food containing trans fats.

An FDA spokeswoman said the agency expects to issue a final rule requiring the labels early next year. Companies would probably have a year or more to comply.

"Once those labels go on, trans fats are history," Nestle said.

And the fight would probably switch to overall fat levels.

The food industry's critics blame fatty snacks and fast food for an increase in obesity -- 60 percent of Americans are overweight, and 300,000 die each year from related illnesses, according to the surgeon general. They say fat-rich diets have led to children developing a type of diabetes that used to be associated only with adults.

Food makers say they offer products for people who want less fat, and it is up to individuals to watch what they eat.

"There are no good foods and bad foods. It's about the totality of what you eat," said Rocco Papalia, Frito-Lay's senior vice president of technology.

Frito-Lay is also expanding its lineup of reduced-fat chips and has hired a Dallas doctor and fitness advocate to develop nutrition and exercise messages on packages.

Walt Riker, a spokesman for McDonald's, said the chain's average customer visits only two or three times a month. He said it would be unfair to blame the restaurants if some customers are overweight.

"There are a lot of choices on the menu. We have salads," Riker said. "It's very basic food. It's quality food."

Brief boost in sales

John Faucher, an analyst with J.P. Morgan, said Frito-Lay would, at best, enjoy a brief increase in sales from the new lines of lower-fat chips.

"The problem is, people tell you they want healthier food," he said, "and then they go out and order a plate of cheese fries with gravy."

McDonald's and Frito-Lay say the timing of their decisions to reduce or eliminate trans fatty acids had nothing to do with fear of lawsuits or the FDA's proposal on labeling trans fats. They compared it to switching from animal fats to vegetable oil for cooking more than a decade ago once the health benefits became clear.

Analysts generally do not see the lawsuits yet as a threat to the companies.

"The idea of suing McDonald's because you're obese is absolutely ridiculous. Just don't eat the stuff," said Jeff Kanter, an analyst who tracks food companies for Prudential Securities.