Robert C. Atkins, maitre' d of the current low-carbohydrate diet rage, looks weary this afternoon. He has just scolded a caller to his radio show for eating Smart Start cereal for breakfast.

"That's Dumb Start! If you don't believe me, test your blood sugar before and after," he tells "Jim," who adds that his triglycerides are "over 800."

"Oh my God!" says the doctor. "Stop eating carbohydrates!"

Seems like everywhere you go, someone has stopped eating carbohydrates. Your sister-in-law, who heard about it from a friend, has lost 12 pounds on Dr. Atkins; two of your friend's office mates are doing Protein Power; the guy you talk to at a cocktail party has lost 25 pounds; the woman your husband had lunch with is doing The Zone.

At least five books are current or recent bestsellers--the champ being "Dr. Atkins' New Diet Revolution" with 158 weeks on the New York Times list--not to mention the subsidiary cookbooks and updates. There are low-carb discussion groups on the Net, low-carb recipe exchanges and low-carb dinner parties.

Low-carbers have thrown off the yoke of low-fat imperialism and food pyramid hegemony--despite the stern disapproval of the medical establishment and the $30 billion fat removal industry. Friends and family watch in shock as they eat bacon and eggs, blue cheese dressing, butter on their broccoli--and lose weight. They have said sayonara to most bread, pasta, sugar and, of course, Smart Start.

Adherents of the low-carb way of life earnestly believe that it is more than just another chapter in the unending saga of American weight loss schemes. The fact that it was the regime proposed in the first successful diet book--William Banting's 1864 "Letter on Corpulence"--only seems to add to its mystique. (Banting, an English casketmaker, had gotten so fat he had to walk downstairs backward.)

Atkins started the current revival of low-carb dieting. His first "Diet Revolution" was published in 1972, his most recent earlier this year. Altogether, his five books have sold 6 million copies, and he's selling power bars and vitamin supplements. His clinic--the 25-year-old Atkins Center for Complementary Medicine in Manhattan--treats 100 patients a day and is expanding. And every day Atkins receives testimonials to his low-carb, high-fat, high-protein regime.

Atkins hasn't eaten lunch on this day; instead he is poking toasted cheese bits out of a cellophane package. But his assistants--slim chief nutritionist Colette Heimowitz and the radio show's producer, tiny Jackie Rudin--have to eat, and they lead a visitor across the street to a Chinese restaurant.

Heimowitz orders a dish with scallops, oyster sauce, mushrooms, broccoli and snow peas. She does not eat the rice. The visitor decides to follow her low-carb suit. But after she has eaten every possible bite, a hunger nags quietly.

"What did you eat for breakfast?" asks Heimowitz, a trim 126-pounder.

Well, it was on the 7 a.m. Metroliner and there wasn't much choice, so it was, well, a bagel.

"A BAGEL??!" Scandalized gasps are heard in unison from everyone at the table.

"Dr. Atkins's book says a bagel is only 30 carbs," the visitor protests feebly.

"No, 50," says Heimowitz.

The bible, "Dr. Atkins' New Diet Revolution Revised and Updated," is produced. There it is: bagel, 30 grams.

"Must be a very small bagel," says Heimowitz.

Carbing Out a Niche

Twenty carbs a day. Thirty carbs a day. In the obsessive world of dieting, these details are major issues.

Each of the best-selling low-carb gurus has a finely calibrated variation on the basic theme, which runs like this: While the low-fat imperialists have long argued that if you eat fat you get fat, the low-carb insurrectionists say, hey, what do we feed pigs and cows to fatten them? Bacon? No, grains. Carbohydrates! That's what makes fat!

Each of the New Lifestyles (few use the word "diet" anymore) starts with a boot camp of at least two weeks during which followers greatly reduce the carbs from their diet, kick the sugar habit, turn their bodies into crackling fires of fat-burning and use a lot of toilet paper.

Of course, all of the low-carb Lifestyles, like every other weight reduction scheme ever invented, are dependent on the same food group: lettuce. Green lettuce, red lettuce, arugula, bibb, Boston, iceberg, shredded, bedded and headed.

After this, the gurus splinter over what to the unpracticed eye appear to be minor differences: Atkins forbids fruit. Protein Power allows carrots, and lets you subtract fiber content from carb totals. Every low-carber finds a different path to enlightenment.

"The Zone," by Barry Sears, a PhD from Massachusetts, should be subtitled "The Diet for Math Majors." Followers must calculate everything that goes into their mouths into "Zone Blocks." A basic omelet requires 16 ingredients, including cornstarch and one macadamia nut. Sears suggests that those who "enter the Zone" achieve spiritual superiority in addition to a reduction in body fat. His latest book is also full of sentences like: "When the stool is isodense with water (i.e. it floats), that becomes a very good indicator of optimal eicosanoid balance." Sounds great.

Some people go with Michael R. Eades and Mary Dan Eades of Little Rock, Ark., the doctor authors of "Protein Power." Among the many charts and lists in their book, they provide handy carb equivalents like "7 Skittles = 3 French Fries" (neither of which one should be eating).

"In college I was obsessed with low-fat," says one 24-year-old Washingtonian who works for a political consulting firm, explaining her devotion to Protein Power. "I would become unglued if I couldn't get skim milk for my coffee. I played four sports a year and worked out. But I never lost weight and I didn't have any muscle."

A year after going on the protein plan, she has lost about 15 pounds, has less body fat, improved her muscle tone and--most amazingly to her--no longer needs to take her six allergy medicines and doesn't get headaches. Both her parents--they are divorced--and her two brothers have lost weight on the program also. "It's the only thing my parents have agreed on in years!" she says.

People like the low-carb diets because they don't have to be hungry and they can eat real food, and the diets do not produce the undesirable side effects of low-fat eating: brittle nails, constipation, dry, limp, thinning hair, infertility, insomnia and itchy skin, as enumerated by Diana Schwarzbein in the foreword to actress Suzanne Somers's new low-carb bestseller, "Get Skinny on Fabulous Food."

Somers (referred to as "yesterday's bimbo" by Atkins's agent) calls her diet "Somersizing." She makes eating lettuce sound fabulous, which is one of her favorite words. In Suzanne's world, food is eaten with her fabulous family and friends, at her beach house, her desert house, her Los Angeles house--never in a non-designer kitchen where the kids are screaming for french fries.

She does require a fairly complicated system of food combining: You can't eat fat or protein with your few carbohydrates, and you have to eat fruit on an empty stomach, or no more than 20 minutes before a carbo meal or an hour before a protein and fat meal. She promises that you can get the hang of it pretty quickly . . .

"Sugar Busters!" followers are attracted by the fact that three of the four authors are doctors (trust doctors to insist on a ! in the title). They are pitching, basically, New Orleans. They all live there and call it the city with the best food and the fattest people in the country. They say New Orleans chefs make just as wonderful food without sugar and processed flour. Their other message: Whatever carbs you eat had darn well better be complex.

There are other subtle differences among the plans. All but Somers want you to take yucky fish oil supplements in addition to a long list of vitamins. (Atkins recommends 30 vitamin and mineral pills a day--he takes 60 himself.) Some allow artificial sweeteners; some don't. Drinking a glass of water before eating is encouraged by a few, frowned on by others (it either is good for filling you up or bad for diluting digestive enzymes). Same with caffeine. But the basic concept--that carbohydrates activate insulin production, which leads to fat--is the same.

Don't expect your personal doctor to endorse any of them. Critics say the high level of fat allowed by Atkins is bad for your heart, and the high level of protein urged by all is bad for your kidneys. They say that eating so few carbohydrates will cause the body to cannibalize itself, to eat muscle and not fat, and that ketosis--the state in which your body is burning fat for fuel--could cause brain damage.

"No one has ever shown me a single case of these problems occurring in a person," counters Atkins. Low-carb partisans, including the Sugar Busters! and the protein powerful, are marshaling more research to validate their claims. But the medical establishment remains skeptical.

"Any diet that tells you eating fruit or carrots is evil--oh, grow up!" says Pamela Peeke, a Bethesda internist with a specialty in nutrition who has debated Atkins on "Oprah." Peeke is writing her own diet book, "Fight Fat After Forty."

She agrees that refined sugars and flours are bad for you, and that all sweet products labeled "low-fat" should be tossed in the garbage can. But she argues that "we spend tremendous time looking at fuel and not at fuel combustion," i.e. exercise.

James Hill, an obesity researcher at the University of Colorado, helps maintain the National Registry of Weight Loss Participants, a six-year-old project to record success stories from people who have lost at least 30 pounds and kept it off for two years. They now have 3,000 self-reported stories, and few have been from low-carb, high-protein enthusiasts, Hill says.

"The great majority have done it the way we usually say they should: They eat low fat, watch total calories and engage in a lot of physical activity, probably an hour to an hour and a half a day," Hill says.

Yeah, we know. But that routine just doesn't seem to work for a lot of people, who are pushing the whole diet drama toward the idea that each person's diet equation has a different solution.

One Born Every Minute

The truth is, there is no truth in dieting. Almost anything--fasting, chugging a glutinous protein drink made of animal parts, counting calories, popping pills, eating nothing but fruit before noon--works for a while. But 95 percent of those who lose weight fail to keep it off for very long.

Thomas Wadden of the University of Pennsylvania's medical school says studies show that few people manage to lose more than 10 to 15 percent of their weight and keep it off.

But who can blame the low-carbers for giving the bacon burger without a bun a shot? Nobody has figured out why some people are thin and others are not--or why we care so much. Why should anyone place his faith in any doctor when physicians in the not-too-distant past prescribed doses of insecticide and injections of pregnant women's urine for weight loss? Over the last 20 years, we've reduced fat consumption, as they told us to, and physical activity, which they didn't. And obesity has gone up and up. Where does that leave us?

The story of dieting in America reflects something about our national character, even if the mirror is the warped glass of a fun house. Inside every sucker is an optimist, a person who believes in redemption. Maybe the pregnant urine will work! Maybe eating nothing but tropical fruit for five days will start you on the road to bikini-land! We believe in reinvention and self-determination. All it takes is willpower. Right?

We are a nation of extremes and imbalance. The actresses on television are getting so thin that other countries will soon think they need to send us foreign aid, but the gap between celluloid women and real women is getting larger. We are lectured constantly about how bad our diets are, but according to the surgeon general only one state (Illinois) now requires physical education for grades K through 12, and meanwhile, fast-food chains are gaining footholds in school cafeterias. And despite general progress in the category of tolerating others, it is still socially acceptable to treat fat people like scum.

So we never give up. Ever.

The Original Revolutionary

"I never wanted to be known as a diet doc," sighs Atkins, leaning back in his swivel chair.

For nearly 20 years, between the publication of his first "Diet Revolution" and his second, he was not very interested in obesity. He stuck to the regime himself, keeping off the 20 pounds he tended to gain, but preferred to spend his professional time on what is now called alternative medicine.

"Eleven years ago I couldn't get him arrested," says his agent, Michael Cohen. Then in 1992, Atkins reissued "The Diet Revolution" because he knew it would get attention and earn money. And, once again, it took off.

But that doesn't mean he's happy about it. "I have a message I must get across," says Atkins, nearly 68. "The more people see me, the higher the probability it will. And that is, that the kind of medicine I've learned is better than the medicine I was taught. . . . I've dedicated my life to this."

Chelation therapy, nutrients and, of course, diet are among the treatments he uses. Some of these ideas have been gaining currency in the mainstream, but not soon enough for him. When reporters interview him, they want to talk only about the diet. So, while the outside world sees him as the successful diet doc, hauling in dollars from his book sales, he is grumpy and bitter at the years he has been rejected as medical seer. The New York Board of Health even tried to revoke his license a few years ago--an attempt made without due process and quickly reversed by a judge.

And now, in his view, all these other people are imitating his diet. "Protein Power" is virtually a carbon copy, he says, and "Sugar Busters!" is close. As for "The Zone"--"I am personally disappointed in Barry Sears," he says, refusing to elaborate.

Atkins was raised in Dayton, Ohio--on a diet of meat and potatoes for dinner and doughnuts for breakfast. And when, he is asked, was the last time he had a doughnut?

"1963," he says. And for the first time, he cracks a smile.

CAPTION: "I never wanted to be known as a diet doc," says Robert Atkins, author of the low-carb "New Diet Revolution."

CAPTION: Carbohydrates are the villains in these books, which disagree on the details. But don't expect your personal doctor to endorse any of them.