Dining with Durk Pearson and Sandy Shaw, America's latest pop fitness gurus, is a bizarre experience. Not that they don't eat well. They do. No brown rice and soyburgers for these two. Such health foods are as irrelevant as exercise to them. Chowing down in Courtney's, a chic gourmet restaurant in L.A.'s Manhattan Beach, they dig lustily into cracked crab, veal stew, chocolate rum mousse pie and raspberry truffle ice cream—not a bad diet for a pair who aim to see the dawning of the 22nd century. The weird part of the meal is the way they eat it. They sprinkle each morsel with a dash of monosodium glutamate and two chemical substances known as nucleotides. And they pause between bites to take a deep snort of Diapid, a nasal spray that contains a synthetic version of a hormone produced by the pituitary gland. Pearson and Shaw, both 39, believe that this regimen improves the flavor of the food, as well as adding years to the diner's life. "We like gourmet food," says Pearson. "It's one of the great pleasures, along with sex and reading scientific journals. Instead of eating dull, tasteless, bland food in order to have a long life, we've found a way we can have gourmet food. I think that's a much better deal, myself."

Such promises are proving very popular with people who long to live forever or die trying. In the past two months some 275,000 Americans have plunked down $22.50 for Pearson and Shaw's hefty, 858-page book, Life Extension. That is more than enough business to propel the unhyped, unheralded—and generally unreviewed—tome to No. 1 on the hardcover best-seller lists. Publishing insiders credit part of the book's success to Pearson's frequent guest appearances on Merv Griffin's syndicated TV show, which first gave him a mass audience for his theories on fitness.

In a way, the book's popularity is not surprising. Pearson and Shaw are saying just what people want to hear: that they can double their life spans without the bother of exercising vigorously or eating carefully, simply by gorging themselves with various diet supplements. "What the book's about is staying young longer and having a higher quality of life for a longer period of time," says Pearson, who once remarked, "I see no reason, unless I get hit by a bus, why I shouldn't live to be at least 150 years old with a healthy body and a quick mind all the way."

Many scientists view the book as rubbish and potentially dangerous. "They advocate using gigantic amounts of nutritional supplements that could have a harmful effect," says one authority on aging, Dr. Robert Morin of Harbor-UCLA Medical Center. "They are really using themselves as guinea pigs. The danger is that the public will do the same." Dr. Caleb Finch, director of USC's Gerontology Center, is more scathing: "Their material would be better presented in Mad magazine."

The duo's controversiality in scientific circles is at least as predictable as their success in bookstores. Their medical credentials are minimal: Pearson has a B.S. in physics from MIT and Shaw a B.S. in chemistry from UCLA. Unmarried lovers and collaborators for the past 17 years, Pearson and Shaw share what they call a "very open" relationship. "Oh, sure, occasionally I get jealous," she says. "I guess it's really anger, but I've found I can control it through nutrients." She says L-tryptophan, an amino acid naturally found in milk, helps especially. As for Pearson, he says, "I'd never leave Sandy because she's the smartest person I know, my lover and my friend."

They met in 1965 as students at UCLA. "I didn't like him at first," Shaw recalls. Later, "He told me I was pretty, and I couldn't believe it. He respected me, and that meant a lot. I had been married for a couple of years to a student, and it was a bad marriage, but I didn't know it until I met Durk. I left my husband and started living with Durk almost immediately."

Until 1968, when they began to formulate their life extension theories through reading scientific journals, the pair pursued separate careers. Shaw worked as a computer programmer and quality control analyst for the company that packs Chicken of the Sea tuna. She was fired for criticizing the management. "I couldn't see behaving in a certain way," she explains. "I couldn't pretend that I was a straight, middle-class type of person. Creative people don't work that way." Pearson, meanwhile, served as a physicist for the aerospace firm TRW and, under contract to NASA, helped design equipment and experiments for the space shuttle. Recently the duo served as technical advisers for the aircraft sequences of the Clint Eastwood movie Firefox, and they have just scripted an upcoming Eastwood epic described as a bio-med thriller. Reports have speculated that Eastwood is one of the book's case histories, a film actor called "Mr. Smith" who credits a "life extension formula" of vitamins and drugs with enhancing his speech, hair and suntan.

The couple live and work in three adjacent houses along the Pacific near Los Angeles. The main house, crammed with souvenirs and garage sale purchases, resembles a storage wing of the Smithsonian Institution. On one wall hangs an engine sectron from the Apollo lunar module. Another room houses Shaw's battery of state-of-the-art computers. The kitchen is packed with barrel-size stores of nutritional supplements. Nearby, a 1965 Pontiac engine hangs from the ceiling. As often as not, though, Shaw and Pearson spend their working hours in their separate bedrooms, on their waterbeds, perusing scientific journals. "We spend way over 40 hours a week reading technical material," says Pearson.

Their dress is as unorthodox as their laboratories. They generally loll about in shorts, skimpy tank tops and sneakers. In their book, they display themselves with even less modesty. Underneath seminude photos in pumping-iron poses appear unusual captions—"Erotic self-image plays a major role in neuroendocrine function ..." says one. Explains Shaw: "The book's message is that people are going to be able to remain youthful even though they are getting older. Well, we are 39 and we have to show people that we look youthful." Pearson, who has been photographed for an upcoming Playgirl spread, agrees. "You might say it's the closest we come to a full-disclosure policy."

Far more controversial than this cheesecake-in-the-service-of-science is the couple's research method. They follow the literature on aging experiments performed mostly on animals and then try them out on themselves. "Sandy and I have done more testing on ourselves than on lab rats," Pearson has said. Daily the pair ingest some 30 different vitamins, minerals, hormones and amino acids—not all of them federally approved. They also gobble up food preservatives. "The body is like a piece of steak, and some of the same aging mechanisms apply to it," reasons Pearson. On nearly every page of the book, however, is a caution from the co-authors. "It's important for people to understand that nothing is safe," warns Pearson, "and that they should be careful to adapt for what their body needs."

On that point, at least, other scientists agree. "It would be unfortunate for people to depend on what they read in that book as a fair assessment of the field of gerontology," says Dr. Leonard Hayflick, director of the Center for Gerontological Studies at the University of Florida, whose work is cited in Life Extension. "It's a glib, superficial overview of the field. I would be very unhappy to learn that there were substantial numbers of people depending on its contents for guidance." However, one of the book's dedicatees, gerontological pathfinder Dr. Denham Harman of the University of Nebraska Medical Center, disagrees. "I think basically the book is sound," he says, adding, "It's nice to see a book on aging on the best-seller lists."

But many scientists believe that, barring a genetic breakthrough, no one can hope to lengthen dramatically his or her life span. Improvements in average life expectancy in recent years have been made largely because of better nutrition and elimination of infectious diseases that cause childhood mortality. The major degenerative ills that affect the elderly—heart disease, stroke and cancer—remain unconquered. Between the ages of 85 and 100, most of the body's systems begin to break down. (Scientists estimate that even if cancer were eliminated, the gain in average life expectancy would only be 214 years.) Reports of supercentenarians living well beyond 110 are often suspect because of the lack of reliable birth records.

Pearson and Shaw profess no concern about attacks on their book. "This is a political mudslinging operation," says Pearson. "There are a lot of emotional charges of inaccuracy and misinformation, but I haven't heard one statement countered or picked out and said, That's wrong.' " The couple are quite confident that they are winning the debate—and if sales figures are any indication, they are. Their publisher, Bernie Shir-Cliff, editor in chief of Warner Books, expects to sell at least half a million copies of Life Extension before the Life Extension Companion, a handbook, appears sometime next year. Pearson and Shaw, meanwhile, expect to outlive their detractors by at least several decades. "We expect to live longer than the traditional three score and ten and would be surprised not to live 150 years," says Pearson. Adds Shaw: "You see, we haven't grown up yet—and maybe we never will."