The key scene in a health-and-fitness guru's biography is almost always the "Eureka!" moment that launches him from obscurity to self-help superstardom. Charles Atlas was skinny and poor until he discovered the chest-expanding secrets of Dynamic-Tension. Dr. Robert Atkins was fat and unhappy until he stumbled across the waist-melting wonders of low-carb eating. Dr. Joel Fuhrman, whose radical ideas on nutrition have made him one of the most influential diet doctors in America today, followed, as he usually does, a different path. Fuhrman was already famous as a world-class pairs figure skater, competing on the same amateur circuit as Dorothy Hamill and other future Olympic medalists, when, in 1973, at age 20, he suffered a life-changing heel injury.

"I couldn't take any impact on it, couldn't jump and land on it," Fuhrman says. "I couldn't walk for almost a year." We're seated in his offices in a bland corporate park in exurban New Jersey, a suite that looks more like someplace to sign papers for a mortgage refinancing than the global headquarters of a health revolution. At 58, Fuhrman is still in excellent shape, a point that he illustrates by pausing midsentence to lift his shirt, flash his well-defined abs, and frog-jump up and down off his desk, an apple in each hand. His default facial expression is a smirk that implies he possesses an important secret, which he may. With a little more hair, he could pass for 15 years younger.

When the U.S. Olympic Committee's orthopedist urged Fuhrman to undergo an experimental surgical procedure for his heel, Fuhrman refused. He sought treatment instead from Herbert Shelton, a San Antonio naturopath who specialized in irregular cures. Fuhrman, a fit 150 pounds, was put on a regimen of only water for 46 days. "They nearly killed me," he says. "I fasted down to 88 pounds." His heel trouble vanished, but so did most of his muscle, and he was unable to regain top form in time for the 1976 Olympics.

A less-farsighted man might have sued Shelton for malpractice. Fuhrman – who'd watched his father use natural methods to rid himself of obesity, osteoarthritis, and back pain – saw an opportunity for a second act away from the ice rink. He earned a medical degree from the University of Pennsylvania, specializing in nutritional medicine, and, in 1995, published the alt-medicine manifesto 'Fasting and Eating for Health.' The book laid out the unorthodox, roughage-heavy rules for maximizing wellness that Fuhrman has since refined and expanded upon for an ever-widening audience. In June, the revised edition of his best-known work, 'Eat to Live,' hit number one on the 'New York Times' bestseller list.

Judging by its cheery, colorful cover, which promises "Lose 20 Lbs. or More in 6 Weeks" and bears a ringing endorsement from celebrity physician Dr. Mehmet Oz ("A medical breakthrough....There is no question in my mind that it will work for you"), 'Eat to Live' ought to be a typical diet book. A reader who cracks it open expecting WebMD-style advice about counting calories and taking the stairs more often might be surprised to learn that the author preaches something closer to fruitarianism or Christian Science than to conventional medical wisdom. In Fuhrman's world, the number of calories one consumes is far less important than the types of food he or she ingests. Low-carb, high-protein diets are not only unhealthy, but they will also almost certainly hasten one's death from an unpleasant disease. Olive oil should be avoided, and the Mediterranean diet is practically a sham. A slow metabolism is preferable to a fast one. "Why would you want to speed up your metabolic rate?" he asked me, throwing his hands up in disbelief. "You're aging yourself!"

Fuhrman's number-one predictor of whether someone will get cancer isn't family history; it's what that person puts in his mouth. "Your genes play a very small role," he says. "And nutrition has the power to overwhelm genetics. The medical profession and the masses have absolved themselves of all responsibility. They think drugs are the answer to everything."

Fuhrman isn't a crunchy holistic thinker. He's a data-analysis guy. He speaks in a combative tone underscored by a medium-thick New York accent and sketches little charts and diagrams to
illustrate important points. Fuhrman says he has reviewed 20,000 journal articles on nutrition, culling the most important information from each. Out of this collected wisdom, tested on thousands of patients over the years, he has devised a simple formula: H=N/C, or health equals nutrition divided by calories. It is the foundation of Fuhrman's proprietary eating system, which he calls nutritarianism. One of the core tenets of nutritarianism is that everyone should eat at least one pound of raw vegetables and another pound of cooked ones each day, the equivalent of a throw-pillow-size bag of spinach and a very large bowl of steamed broccoli. Follow his advice, Fuhrman promises, and you should stay healthy until at least the age of 95.

Nutritarianism is part of a growing school of research-based dietary thinking that insists that, in terms of wellness, you really are what you eat. Call it plant-based libertarianism. The U.S. has the world's highest healthcare costs – $2.7 trillion in 2011 – while consistently scoring lowest among developed nations for quality of care. Practitioners of plant-based libertarianism believe that every person needs to take full responsibility for his or her own health. This means adopting a wellness-focused diet, mostly vegan.

Comprehensive improvements in diet have long been shown to reverse, slow, or prevent what are called "diseases of affluence," largely self-inflicted maladies like obesity, coronary heart disease, stroke, and type-2 diabetes. More recent research suggests that such dietary improvements also combat Alzheimer's and cancer. This movement shares some of the life-extension dogma of the calorie-restriction crowd and a little of the anti-agribusiness, eat-local moralism of writers like Michael Pollan ('The Omnivore's Dilemma') and films like 'Food, Inc.' Its primary concern, however, is wresting control of America's health back from the insurance and drug companies and returning it to the hands of citizens. As Fuhrman puts it in 'Eat to Live,' "only you, not your physician, must take responsibility."

"In the future, it's going to become more and more impossible for the economy to support how expensive medical care is and the number of sick people we have," Fuhrman says. "Why don't we just get our population healthier so we don't need medical care?"

Along with Fuhrman, the leaders of plant-based libertarianism include nutritionist T. Colin Campbell, co-author of The China Study, and his comrade-in-arms Dr. Caldwell Esselstyn, a cardiovascular surgeon. Last year, Campbell and Esselstyn starred in the hit documentary 'Forks Over Knives' – the title reflects a preference for dietary intervention over the surgical variety – and published a bestselling book of the same name. Perhaps the biggest brand name in the field is Dr. Dean Ornish, whose near-vegan diet helped Bill Clinton drop 24 pounds following a second coronary surgery. Fuhrman is something of an outlier among this group in that he argues that small amounts of fish, eggs, and low-fat dairy are permissible so long as a person cranks up the rest of his diet to meet the ultrahigh nutritional benchmarks set by the H=N/C standard. "The right raw materials can...double or triple the protective power of the immune system," he writes in his latest book, 'Super Immunity: The Essential Nutrition Guide for Boosting Your Body's Defenses to Live Longer, Stronger, and Disease Free.'

The nutrients that most interest Fuhrman aren't found in supplements or multivitamins. He focuses instead on the immunity-boosting power of micronutrients. These include antioxidants and phytochemicals, which he calls "the most important discovery in human nutrition in the last 50 years," though most of them have yet to be named or even identified. The foods highest in micronutrients per calorie are unprocessed plant foods, mostly fruits and vegetables, which make up 90 percent of an ideal nutritarian diet. In Fuhrman's system, calorie-dense olive oil (nine points) scores lower than white bread (18 points) because its phytochemical load is so low relative to its fat content.

"If you want ideal health, you need to overcompensate and eat an excellent diet," Fuhrman says. He estimates that if all Americans were to adopt a nutritarian diet, "the immediate impact is that cancer rates might decrease by half. But the long-term impact, over generations...." He picks up a pencil and draws a downward-sloping line. "If we get kids eating right, we could decrease cancer rates by 90 percent."

Like most evangelists, he maintains few barriers between his professional and personal life. At least one patient recalls arriving for an initial consultation and receiving an invitation for her family to swim at the Fuhrman home in New Jersey later that day. Fuhrman's wife, Lisa (age 53; looks a very fit 40), manages his online business and co-stars in his cooking DVD. The four Fuhrman children, ages 10 to 24, have been raised on a plant-based diet but are allowed to make their own food choices outside the home. According to their father, they almost always stick with the program: "One of my daughters once joked that for her, a cookie would be like shooting up heroin or smoking pot." Fuhrman often cites his children as examples of the benefits of nutritarianism – he cannot recall a single ear infection or case of the flu among them. Unlike most family practitioners, Fuhrman gleefully picks fights with other doctors, particularly those whose diets he disagrees with. "The Dukan Diet, the one Kate Middleton was on? That's the stupidest diet in the world," he says, scoffing at the high-protein plan.

The competitive fire that once drove Fuhrman as a skater is now largely channeled into marketing. Drfuhrman.com offers free nutritarian eating plans, with consultations, for overweight brides-to-be who wish to lose 50 or more pounds by their wedding day and are willing to provide a testimonial online "and possibly in magazines and on television." Fuhrman's "3 Steps to Incredible Health" special – essentially a stylish infomercial for nutritarianism – has become a staple during the self-improvement bloc of PBS pledge drives. As an author, Fuhrman has one distinct advantage over virtually all his neighbors in the diet-book aisle at Barnes & Noble: He is an entertaining writer with a gift for plucking fascinating facts and figures out of dry journal articles. (Two random examples: Three servings of cruciferous vegetables per week lower the risk of prostate cancer by 41 percent. Linebackers are six times as likely as endurance athletes to die young.)

If you've set foot in a Whole Foods, you may have noticed that the fruits, vegetables, and dairy products are labeled with an ANDI (Aggregate Nutrient Density Index) score, a number calculated with Fuhrman's H=N/C formula. (Leafy greens, like kale, low in calories and packed with phytochemicals, score a perfect 1,000.) "In my 31 years at Whole Foods, these scores are one of the biggest successes we've had," says Margaret Wittenberg, the company's global VP of quality standards and public affairs. "There's times we've had stores run out of kale." Fuhrman also recommends large quantities of onions, garlic, berries, and mushrooms, all of which he credits with anticancer properties. "Women who ate mushrooms in China had a 64 percent lower incidence of breast cancer," he says, citing a recent study. "That should've been on the front page of the New York Times."

Micronutrients, Fuhrman contends, are also one of the unacknowledged keys to understanding the American obesity epidemic. Americans get less than five percent of their calories from unprocessed fruits and vegetables that aren't white potatoes; 62 percent of our calories comes from nutrient-poor processed foods that are usually loaded with carbohydrates. Fuhrman believes that we overeat these foods not only for the dopamine rush they supply but also in a futile attempt to make up for a micronutrient deficit. The more junk we consume, the more toxins, like free radicals, amass in our tissues. "We become addicted to this toxicity buildup like it was cocaine or nicotine," Fuhrman says. "When we try to stop eating, we get withdrawal symptoms." These include the gnawing sensation in the stomach, irritability, and light-headedness that 99.9 percent of us would identify as hunger.

Fuhrman says these pangs are fake signals, an overriding of natural appetite that should kick in only once the body has exhausted its glycogen stores. The not-unpleasant sensation he calls "true hunger" is felt in the throat, neck, and mouth rather than the belly. It can be satiated by consuming almost any healthy food. Any urge that might qualify as a craving is, by Fuhrman's definition, a sign of food addiction.The idea that a restrictive diet might hold the antidote for all modern ills isn't new. In a famous 1939 study conducted by the Rockefeller Institute, a thousand rats were fed a diet equivalent to that of the average American. The rodents developed 39 different diseases of affluence akin to those seen in the human populace. Another thousand rats were fed a calorie-restricted, raw-food diet modeled on the ascetic customs of a long-lived tribe in the Himalayas. Not one rat in the second group became sick in two and a half years. That story actually did make the front page of the 'New York Times'.

Yet our faith that science will develop a pill or procedure to cure whatever ails us is unshakable. Since the Human Genome Project began spilling the secrets of DNA a decade ago, many of our hopes have been tied to the potential discovery of particular genes linked to specific disorders that, once decoded, will offer road maps for doctors and drug researchers to follow. But the potential of gene therapy as a cure for cancer remains limited. One comprehensive review of cancer-prevention research estimated that only five to 10 percent of cancers resulted from inherited gene defects. The same study found that 30 to 35 percent of cancer deaths are "linked to diet," with an additional 10 to 20 percent linked to obesity. Prostate cancers had a 75 percent dietary cause.

"We know that cancer is a preventable disease that requires changing lifestyle," says Bharat Aggarwal, a professor of experimental therapeutics at the M.D. Anderson Cancer Center in Houston. "No matter which cancer you pick, they've found out at least 200 to 500 genes have gone wrong. That means 200 to 500 pathways. The drug industry knows how to target only one pathway at a time. Natural products hit multiple pathways, so they slow down the progression of the disease."

Fuhrman is flabbergasted at the amount of money going into cancer-cure research. "We're not going to find a magic cure for cancer," he says. "We've got to prevent it."

Micronutrients, in his opinion, are "the fuel that turns on our body's anticancer defenses." Animal protein, on the other hand, raises levels of IGF-1, a hormone that stimulates growth in children but promotes tumor development in adults. Dr. Luigi Fontana, who conducted a multiyear study on long-term calorie restriction, observed a correlation between protein consumption and IGF-1 levels. "There's a perception that you can eat as much protein as you want," Fontana says, "and it's safe and healthy. Our data suggests that probably this is not correct."

With each book, Fuhrman has pushed the possibilities of nutritarianism a little further. A banner running across the bottom of 'Super Immunity's' cover promises, in capital letters: no shots – no drugs – no sick days. Fuhrman writes that "healthy people eating healthy food should never need to take an antibiotic." In his office, he dials that claim back a little, saying that antibiotics might be necessary on "very rare occasions." I ask for examples.

"Certainly, you could step on a sea urchin," he says. "You could get bitten by a cat."

Viruses, Fuhrman says, are relatively harmless in a healthy person; a bug that kills one person might not even cause symptoms in a committed nutritarian. Because Americans are hooked on immunity-depressing "fast food and sugar and junk," we aren't prepared for the kind of viral pandemic such as the 1918 Spanish flu, which killed at least 50 million people worldwide. "Some sort of swine flu/bird flu hybrid could kill 20 percent of our population," Fuhrman says. As for the annual flu shot, "it isn't effective at all – it doesn't work!" He's also skeptical about the number of vaccines the average American child receives. "There's no chance of anyone getting polio in this country," he says.On a chilly Friday night in Princeton, New Jersey, more than 300 people who have paid $800 and up for one of Fuhrman's Weekend Immersions have arrived at the Hyatt Regency. The event is sold out, and a spacious ballroom that has seen its share of rented tuxes and bridesmaid dresses is filled with an odd cross-section of the Fuhrman faithful and curious newcomers. Ectomorphic women with yoga arms wander aimlessly between the tables as if searching for their mislaid kombucha. Wide men with rolls of fat bulging from the back of their necks sit with their arms folded, their grim facial expressions hinting at recent bad news from their cardiologists.

I found a seat next to a slim fellow named Rob Alexander-Carew, who'd flown down from Toronto. He'd been following a nutritarian program for four months. "I've lost 30 pounds," he told me. "I'm the same size I was when I was 15." He started eating nutritarian in hopes of finding relief for his pulmonary fibrosis, a scarring of the lungs with no known cause or cure. Though he looked like a cross-country runner, Rob was down to 60 percent lung capacity.

"Do you feel like it's working?" I asked.

"I'm lighter and fitter. My kids come home with a cold and I catch it, but 12 hours later it's gone, and I'm like, what just happened? But my lungs haven't opened up yet."

I noticed that Rob was picking at his nutritarian dinner – steamed kale in creamy cashew sauce.

"Any foods you miss?" I asked him.

"Bread," he said, stirring his vegetable soup. "I really miss bread."

Fuhrman took the stage, flanked by slender acolytes dressed in black. He gave a short speech, exhorted the audience to "Change your life!" – and was followed by testimonials from patients relating the miraculous changes they'd seen under his care. One had overcome rheumatoid arthritis; another had lost 144 pounds. A children's book author with stage-four ovarian cancer had eaten her way back to health.

All this sounded completely plausible to me. I had followed Dr. Fuhrman's Eat to Live plan for six weeks, and the results were undeniable. But it's hard to be perfect all the time, even if the payoff is near-eternal health. I don't know how many people who aren't facing imminent death – or who wouldn't be capable of living on water for 46 days to cure a heel injury – would have the willpower to stick with nutritarianism forever. When it comes to the link between diet and health, Americans not only expect to have our cake and eat it, too, but we also insist that our doctors prescribe something to undo the consequences of our gluttony. In the months after meeting Fuhrman, as I tried to weave some of his dietary precepts into my life, the second-biggest story in health news was First Lady Michelle Obama's inexplicably controversial initiative to encourage kids to exercise and eat more vegetables. The biggest health-news story was that the FDA had granted preliminary approval to a new anti-obesity drug.

Fuhrman puts forth a convincing case that by making some fundamental dietary changes – sacrifices, really – Americans can live longer, healthier lives. The question is, can we live with that?

The Fuhrman Plan: How to Eat to Live

The regimen: The cornerstone of Fuhrman's Eat to Live plan is a six-week starter phase during which a person adopts his nutritarian diet. The first month, Fuhrman promises, the average person will lose 15 pounds by expunging his diet of animal products (including dairy), oils, added salt, caffeine, fruit juices, alcohol, potatoes, and all refined carbohydrates. One to two servings of egg or fish per week are allowed, provided no more than 10 percent of calories come from protein. (On a per-calorie basis, Fuhrman says, broccoli has double the protein of steak.) You are permitted to eat as many vegetables, fresh fruits, and beans as desired. Overeating, Fuhrman says, results from poor eating habits, which leave the body starved for nutrients. "Completely rethink your idea of what a portion is: Make it huge," he writes. That means at least one pound of raw vegetables a day, plus a pound of cooked; four fresh fruits; and a cup of beans. Limited amounts of raw nuts, seeds, whole grains, and avocado are allowed. No calorie counting is required. No snacks are permitted.

The benefits: What can a budding nutritarian expect in return for these lifestyle changes? Fuhrman promises improved sleep, increased immunity, and more energy. Ninety percent of type 2 diabetes patients can leave insulin within a month, he says; 80 percent of headache sufferers – including those with migraines – recover without medication. The price of admission to this natural-health nirvana is several days of mild discomfort (headaches, light-headedness, hunger) as the body detoxifies from its habit of indulging every craving with food.

The results: I tested Fuhrman's ideas for six weeks, though I did allow myself a small cup of black coffee. My detox phase lasted about four days and wasn't especially unpleasant; any hunger pangs I had could be avoided with punchbowl-size portions of leafy greens. After a couple of weeks, my skin was clearer and felt more supple. I slept a little better but didn't feel any amazing surge of mental energy. I didn't catch colds that my children brought home, and the stomach bug that had pestered me for months vanished. My blood pressure dropped, my physical stamina improved, and my personal trainer didn't notice any dip in strength, despite my vacation from animal protein. I lost about nine pounds and two inches from my waist. Unfortunately, while Fuhrman insists that one's palate adapts to the nonpiquant pleasures of nutritarian cuisine, mine was a holdout. Twice, I awoke at night convinced I'd dreamed of the world's most delicious food. The third time, I jotted it down. In the morning, the taboo delicacy haunting my subconscious was revealed in my handwriting: Mustard.