MIAMI -- I am looking out the 13th-floor windows of my room in The Everglades Hotel, downtown Miami.

The view is heady: six cruise ships, dozens of sailboats and large yachts, downtown Miami's new Bayside waterfront development (a Rouse project like Baltimore's), and the water "runway" for the Chalk Airways seaplanes which regularly ferry passengers to and from the Bahamas out-islands.

Fast, deep-throated speedboats are rushing by, too, a` la "Miami Vice," and a live band is playing modern jazz by the waterside. A lot of people are having a good time down there, and I can't help but think downtown Miami has come a long way.

A very beautiful lady said much the same to me this morning at breakfast. I ordered a two-egg Spanish omelet (made at my request with only one egg yolk and margarine rather than butter). She ordered a fruit cup, which didn't surprise me since my friend is a fitness buff. But then she did surprise me by pulling a small envelope of tea from her pocketbook and handing it to the waiter.

"It's a special green Chinese tea from my new nutritionist," she said, with a big smile. "Lots of people are losing weight with it, he says. As long as you eat less and take the vitamins."

What vitamins? "Oh, the natural ones. He only sells natural ones."

I asked about the nutritionist's background as two cups of green tea were placed on our table. The aroma reminded me of lilies of the valley in its sweetness.

"Oh, he's run a health food store here for some time. The guy just makes a lot of sense in what he says, you know. And he looks so healthy. And he showed me a lot of letters from other people who've been helped with this stuff."

My friend knows me well enough to read my expressions pretty accurately. She paused momentarily, changing her positive smile to one we all can muster when we feel a lecture coming on, then said: "And he's not a quack, either. He knows a lot more about nutrition than you do. And it works for me."

It's a very pretty day here in Miami, and I didn't want any storm clouds coming up over a cup of tea. I changed the subject to boats.

I filed away the conversation, however, under my "health seeker" category of those otherwise sensible people who eagerly latch on to the latest health and nutrition fads without doing the proper research.

During the past 18 months I certainly have not become an expert on health, fitness or eating. But I have spent a lot of time listening to the people who teach, research and understand the basic mathematics of these fields.

By mathematics, I mean the building-block realties: Two plus two always will equal four in math; fire is always hot, whether or not we understand the physics behind the fact; increasing your caloric intake more than your caloric expenditure will eventually make you gain weight.

I, of course, knew these things. You wouldn't catch me buying a book or product, for instance, based on the principle that 2 plus 2 equals 5 or that fire comes from the mouths of dragons with very bad breath.

You wouldn't catch me buying a book or product, for instance, based on the principle that 2 plus 2 equals 5 or that fire comes from the mouths of dragons with very bad breath. During the past year as I listened and learned, however, I found out that I did not at all know the basic mathematics related to health, fitness and nutrition.

For instance, when I first moved to Grand Bahama to begin my deblimping, Jourdan, a diving pal, recommended Fit for Life to me as a nutritional blueprint for my year-long remake. Fit for Life, if you don't know, is probably a best-selling diet/life style book and has turned its authors, Harvey and Marilyn Diamond, into respected, even revered authorities for hundreds of thousands of people.

"They say eat only fruit in the morning, and don't combine certain foods," he said. Well, I had always felt that big breakfasts weren't for me, and thought it sounded perfectly logical that certain foods might not get along in our stomachs. Like chocolate milk and catsup, for instance.

I had also seen the authors on a respected national talk show. I hadn't watched the whole program, but remembered that these people appeared awfully sincere, sounded authoritative, and attacked some traditional nutritional thinking (such as the concept of the four food groups) as old hat.

That last point sounded particularly appealing to me. My memory was chockablock with once-gospel medical facts now disproven. Nutrition, like everything else, seemed to be a very dynamic field where everything was changing because of research and no particular field of thought ruled.

The Diamonds certainly made that point, too. Every time a critic attacked them, they rebutted very effectively with their own experiences. All of that, and the talk show host had said he lost weight and felt better with their plan, too.

I bought the book, and, resting in my hammock, liked what I saw on the first flip-through. The publisher was one of the country's best. The book was introduced by a doctor. The Diamonds had credentials that sounded impressive (he, for instance, held the "highest certificate" from the American College of Health Science and also headed up an impressive-sounding institution).

The book quoted people who sounded authoritative and sported accreditation from impressive-sounding institutions, too, and Fit for Life had lots of sources. I don't check out bibliographies much, but am always comforted by the accountability they imply.

As I looked further into the cited resources, however, my first doubts about this book (and the first days of my education in the mathematics of health, fitness and nutrition) began. If the Diamonds thought that much of the conventional nutritional community's thinking was "old hat," why were some of their most important premises supported primarily by very old studies rather than very new ones?

For instance, one major premise, food combining, was based on a 1902 study by Ivan Pavlov, the dog man, and a 1924 article in the Journal of the American Medical Association. If these sources were still valid, wouldn't there be an awful lot of supporting documents for their findings over the years? Where was the documentation?

And then something about another primary authority cited, T.C. Fry, rang a faint bell. I called a researcher friend. "Yes, he operates an unaccredited naturopathic 'school' in Missouri to which the American College of Health Science in Austin, Texas, is affiliated. But the National Council Against Health Fraud has found that the Austin school is just a post office box." Another bell. The American College of Health Science was the school from which the Diamonds had their nutrition certificates.

The idea that food "rots" in the stomach, said the physicians and scientists I checked with, makes absolutely no physiological sense. I looked more closely at the theories in the book, particularly the basic idea that if one "combines" certain foods (such as eating meat and potatoes together, or eggs and toast, or milk and cereal, or bread and cheese), the food then "rots" in the stomach. The idea that food "rots" in the stomach, said the physicians and scientists I checked with, makes absolutely no physiological sense.

As I read and researched further, I realized that the nutritional math of Fit for Life didn't work. Too many ideas presented in the book were simply not backed up by long-term, controlled scientific research that was statistically valid. Indeed most of these ideas were counter to statistically valid research.

So why did I nearly fall for the Fit for Life approach? I trusted my diving friend's recommendation based on his personal experience; I liked the way the Diamonds presented themselves as much as their information; I believed in their lofty sounding degrees and supposedly legitimate sources without checking on them, and finally I believed that television (or any other media, for that matter) and large numbers of book sales made the message of Fit for Life legitimate.

Like it or not, personal testimonials and the sincerity of a person's presentation does not necessarily make any product or opinion accurate. Carefully designed, properly controlled, replicable studies which prove statistically valid over the long term are the only assurance any of us have that a diet or a medical treatment or a simple over-the-counter product such as a vitamin can benefit us.

My friend in Miami trusts her green tea and natural vitamins because she likes and trusts the seller. Because he is personable and caring (as opposed to the impersonal, cold, bureaucratic "scientific community"), she takes his word that the more expensive "natural" vitamin is superior to the chemically produced one even though both are molecularly identical and function identically in the body, a fact confirmed by statistically reliable studies which again prove that two plus two always equals four.

I do not disagree with all alternative approaches. I am sympathetic with many complaints about "the establishment view" of health, diet and fitness. But until the alternative medicine proponents such as the Diamonds can provide us with scientifically objective studies that statistically support their conclusions, I believe we all should continue to listen to common sense in its most basic form: Two plus two should always equal four.

Now you may be thinking that I've been a bit tough on my friend with the green tea and on the ideas in Fit for Life. What about the arguments for their point of view?

A fair question to which I offer a challenge in response: I'll be happy to present the opposite point of view on diet and fitness as long as the proponents of these views can point me to the reliable scientific studies that provide statistical validity for that position. Please do write, but don't forget those bibliographies.