Brown rice and chandeliers: Pritkin has invented $150-a-day deprivation, served in gilt-framed comfort to the victims of urban luxury.

In resort-motel splendor, several dozen corporate managers, lawyers, teachers and heavy-earners who have eaten and drunk their way up the ladder of success learn to recognize, cook, order and count the calories of whole wheat and squash. They learn there is life after salt. They learn how to walk.

More than 10,000 "patients" have been through the Pritikin Centers' low-fat, sugar-free, salt-free, low- cholesterol, high-exercise program by now, claims Nathan Pritikin. The newest and smallest of the three--the year-old center in Downingtown, Pa.--has shifted the balance from the ill (those with heart disease, hypertension and diabetes) to the "healthies," people who are simply overweight or are interested in improving their eating habits.

While the first two centers require 26-day stays, at Downingtown most participants stay only 13 days. We checked in on a Sunday, a group of 35 participants, half men and half women, 14 of them married couples, all of them over 40 and many of them healthy. For those two weeks, the center's lecture halls, dining room, lounge, examination rooms and gymnasium became our summer camp.

We start with the first of countless lectures, this one by Pritikin himself in his sole appearance before our group. He explains that human beings should live to be 105, and should be playing tennis --doubles, anyway--until they are 95. His center is going to aim us toward that goal.

Monday we have medical exams and begin the endless series of lectures. We grow impatient with the slow start --and apparently so has the staff: in the months since my visit, the center has speeded up the process.

Weight loss is not stressed here, but most women are put on 800 calories a day, men on 1,000. I cut my calorie intake to 600, skipping the twice-daily soup snacks and the evening fruit. We are responsible for our own portions, and many--at least at first--misunderstand, piling on double-size portions. The diet is only 5 to 10 percent fat, and unlike the typical 20 percent American average, complex carbohydrates account for 75 to 80 percent of the diet; the sodium level is 2 to 4 grams.

Breakfast is self-service: hot cereal (with skim milk and no sugar), bran, bagels, english muffins, fruit and occasional terrible gummy pancakes. At lunch and dinner there is always a salad bar, with several surprisingly good fat-free dressings. The lunch buffet also has soups--and the kitchen has soup-making talent, except when faking creaminess--and some culinary surprise. With no-salt cooking, tomato dishes satisfy best: caponata, stuffed pasta shells, enchiladas. Felafel has slow going with this crowd, and rice noodles with water- saut,eed vegetables sorely misses seasoning. There are also homemade breads, fresh Silver Queen corn on the cob, ripe fruits. Herbs are usually fresh and all fresh foods are top-notch. Dinner is served by waiters rather than self- service, and becomes a leisurely and congenial time.

As the weeks progress we learn to accept tofu-mac and whole-wheat lasagna. Teriyaki vegetable kebabs are favorites, and wild rice is luxurious even without salt or butter. We learn to spice dull meals with chili powder and garlic, wash down dry and dreadful tofu-greens fritters with herb teas and non-alcoholic beer. This diet is too restricted to be always satisfying, but the kitchen is professional and inventive. We have few complaints, except that it would be nice to have teas available throughout the day and Perrier for our hotel rooms.

We become pals and drag each other off to one more class or lecture or water exercise session. On non-swimming days, we pedal stationary bicycles, walk treadmills or just walk. Our exercise cards are checked daily and our pace steadily increased, depending on our pulse rates.

People with cardiac problems are monitored throughout each session. One of our group winds up in the hospital cardiac unit the first week. She returns shaky and weakened, complaining that her symptoms had been ignored before she was hospitalized and that no Pritikin doctor visited her in the hospital. The director counters that she was carefully monitored and that her incident was not particularly serious anyway.

On Friday, the diet and exercise leave me weak and nauseated; typical, I am told, as is weekend depression, when some families come and activities are decreased. On Sunday, a robust and fit- looking Pritikin alumni group visits, and suddenly life holds more possibilities.

By Monday I need less sleep, and I can smile during exercise. My quick weight loss has slowed, but my face and shape show change. Group discussions and rap sessions are livelier.

The staff members are young, educated and well trained, but they are at their best when they engage the group's talents rather than try to tell the president of a large corporation or a teacher with decades of experience what stress is or how to be assertive. Some of the program is embarrassingly silly: an alumni group who counteract much of the dietary information we are being taught, a song-and-dance team suited to a nightclub rather than our informal lounge, a simplistic lecture on body language. Massage is fun, videotaped movies are a relief, and lessons on label reading and shopping and dining out are useful. We learn that one bite of meat equals a mile of walking, two beers three miles.

By the last day I have lost 81/2 pounds; some men lost as much as 20; some people gained. My cholesterol, never high, has dropped 60 points. Most women have lost four pounds, and most guests have lowered their cholesterol and blood pressure. Wine is served at the final cocktail party. Dinner ends with Pritikinized cheesecake decorated with a flower. We truly feel like celebrating, and we vow to join for a reunion at Pritikin.

We haven't. Pritikin's reunions are outlandishly expensive, for one thing. But we have kept in touch. One diabetic, who came nearly blind, virtually inactive and scheduled for an eye operation, sent us all a hand-drawn card at Christmas. Her sight returned without an operation, she has lost 18 pounds and is immensely active these days, even planning to open a restaurant. Several men continued to lose--several of them as much as 40 pounds--and have continued exercising and stopped drinking.

But as impressed as we were with the Pritikin regimen, many of us are left with complaints about the center. Its price is very high--about $2,400 for two weeks. And though some participants submitted portions of their Pritikin bill to health insurance companies, (some companies will cover some costs), six months after their departure the center still hadn't submitted proper documentation for two participants, despite repeated requests. The prices of refresher visits --$500 to $600 for a weekend, $300 of which is just meals and hotel--discourage returns. Guests continue to be asked to refer others and are promised of rebates for doing so. It all smacks of excessive commercialism. And some of the professional staff volunteered that the program lacks important medical components: lung testing, a psychiatric and stress reduction program. There were complaints by some participants of insufficient medical coverage; as of my visit, physicians were on duty only 41/2 days a week.

Some procedures have been changed; in fact, a staff member reported that Pritikin has bought out his partners. Some of the lackadaisical procedures, such as not acknowledging my deposit for two months or sending me directions and a packing list, were supposedly improved. On the other hand, some of the best exercise instructors have moved on, and, according to one staff member, complaints from patients have been dealt with inflexibly by administrators.

The problems are more than such a serious and expensive program should allow. But Pritikin's program does change lives, clearly improving the health of many of its participants. And I can't say I've ever been at a more terrific summer camp.