But others say that no matter what happens to the company founded by Dr. Robert Atkins, the late cardiologist's vision of what the American diet should become has forever changed the nutritional landscape.

The company says it's business as usual for dieters. Colette Heimowitz, an Atkins spokeswoman, says the bankruptcy "will allow us to grow without the crushing debt. Day-to-day operations will continue."

Critics say the once-wildly-popular plan, which slashes consumption of breads, pasta, potatoes, rice, cakes, cookies and some fruits and starchy vegetables while beefing up protein, is going the way of the grapefruit and cabbage-soup diets.

For months, there have been news reports that interest in the diet is waning as people move to more moderate variations such as the South Beach diet.

"The low-carb diet is on life support," says registered dietitian Keith Ayoob at the Albert Einstein College of Medicine in New York, a longtime critic of the Atkins diet. "The bloom is off the low-carb rose. People got bored with it. After a while, they wanted to have an apple or a slice of bread."

But others say diehard Atkins fans will stick with the program. The bankruptcy news "does nothing to deter me from following the diet," says Andrea Mondello, founder of www.low carbeating.com. "I've lost 120 pounds on it, and I feel great. I'm healthier than I've ever been."

Atkins published his first book on the diet in 1972. The revised version, called "Dr. Atkins' New Diet Revolution," was a huge best-seller two decades later.

The company has been selling low-carb products since 1997. They have included bars, shakes, cereals and bread. But recently, sales have suffered because the market is supersaturated with such foods, Heimowitz says.

She says Atkins Nutritionals plans to continue making its nutritional bars, shakes and candy but will ditch breads and chips. The company will provide wider choices in foods that contain whole grains and fruit, she says.

She says the diet has been unfairly pigeonholed as a very low-carb diet. The first two weeks on the plan only allow 20 grams of carbohydrates a day, but then dieters are allowed more carbs depending on their height, weight and activity level.

After the first phase, it is about "choosing good carbs, healthy carbs," Heimowitz says. "Anyone familiar with the Atkins lifestyle knows it is about avoiding added sugars and processed white flour while emphasizing the nutrient-dense carbohydrate choices such as deep-green vegetables and whole grains."

Mondello believes the basic diet has had a major impact on Americans' eating habits. "It has made everybody think twice about processed foods, which is a good thing no matter how you look at it.

"It made people think about reading labels. It made everybody take a hard look at white flour, white sugar and high-fructose corn syrup," she says.

It also prompted people to focus more on consuming protein, she says. A recent study showed that if you eat enough protein, you're more likely to feel full and eat less, Mondello says.

Gary Foster, clinical director of the Weight and Eating Disorders Program at the University of Pennsylvania School of Medicine, says there are probably "fewer people following a strict interpretation of the low-carb diet now than there were two years ago at its peak. But I still have the sense that carbs are part of the consciousness of people trying to watch their weight."

More people may be having their hamburger without the bun or being more attentive to avoiding processed foods, says Foster, who is leading government-sponsored research on the Atkins diet. It's examining the diet's effects on weight, arteries, body composition, bones and kidneys.

Several studies of low-carb diets show that people lose weight while increasing their HDL (good) cholesterol and decreasing their triglycerides, blood fats linked to coronary disease.

Ayoob says many dieters he has talked to are fed up with cutting carbohydrates so dramatically. They want a more modified approach so they can still have their favorite foods. "They want to have their pasta, but they're willing to eat a sensible portion with lots of vegetables."

Ayoob is the author of "The Uncle Sam Diet," based on the government's new dietary guidelines. He says there are lessons to be learned from the Atkins story. "I hope people will remember that restrictive dieting is temporary, and a healthy eating style you can take with you forever."

But Foster says some form of the low-carb diet is here to stay. "It's so hard for many people to lose weight using low-fat, low-calorie methods that there will always be a place for reduced-carbohydrate approaches."