IN ONE of the great understatements of modern journalism, the business pages of The New York Times reported last week that "Analysts have said that food companies with fat substitutes that can reduce both the calorie and cholesterol count of such foods as french fries and ice cream and still please consumers' palates stand to develop large markets for their products."

Stand to develop large markets? How about stand to produce pandemonium in the supermarket aisles?

For who among us is so effortlessly slender, so ascetic in taste that the thought of a calorie-less, palate-pleasing hot fudge sundae would not arouse the most deeply-sublimated desire to gorge?

Clearly the only thing standing between the NutraSweet Co. -- the developer of Simplesse, the aforementioned fat substitute (and Proctor and Gamble which has its own variant dubbed Olestra) -- and riches beyond its wildest dreams is approval from the Food and Drug Administration. P&G has already submitted its invention, a synthetic molecule that passes through the body unchanged, for FDA approval. But NutraSweet alleges that its product, which is a protein digested like all other proteins, doesn't need FDA approval because it is a food, not a drug -- a judgment not yet concurred in by the regulatory agency.

This is not a judgment that FDA should rush to. At risk are issues far more abstruse than the measuring of chemical hazards and the weighing of nutritional risks and benefits. We are dealing here with the most fundamental questions of vice and virtue, of human bondage to the temptations of the flesh.

Yes, of course, we have already accommodated our ethos to the availability of artificial sweeteners such as NutraSweet's highly successful aspartame. These are not, perhaps (depending on what issue of the Harvard Medical letter you read), without their risks to health and many people have shouldered the burden of extra denial associated with eschewing even the occasional packet of sugar substitute.

But sugar substitutes do not really reach to the heart of the moral choice for one simple reason: Sugar (at a mere 16 calories a spoonful) is not what dieters really lust for. Fat (at 36 calories in a mere pat of butter) is.

Anyone who has ever tasted a low-calorie cupcake, or low-cholesterol lasagna will attest that what was lacking, what made the item so straight-out godawful was not the absence of real sugar but the absence of fat. Margarine isn't butter, and neither is safflower oil. But in a pinch they will do. What won't do is no fat-tasting substance at all.

And that is why the invention of Simplesse (or Olestra or whatever) is so momentous an event on the moral landscape. It opens up entirenew horizons of guilt-free indulgence. AIDS may have vanquished free sex, but who, in their hearts of hearts, ever really believed it was a free ride any way? Now, at last, the possibility of retributionless indulgence is in sight.

But, mark my words, there will be consequences. Big ones. I don't mean inevitable downturn in the economic fortunes of fat farms, spas and exercise salons. Other industries of far more consequence to investors and workers have died on the altar of consumer choice.

What should give the FDA pause -- or, at least, prompt it to seek the highest counsel before rushing to approval, is this: When gluttony has lost its sting, what vice will replace it?

The importance of this question was first brought home to me by a colleague, Robert Pugh, now a professor of decision sciences at George Mason University, who was the first, as far as I know, to articulate the theory of the individual quotient of vice (IVQ). Pugh, at the time, had recently given up smoking, a vice to which he had been happily addicted. He observed, true scientist that he was and is, that within the space of a few weeks he had not only gained the obligatory additional pounds but, willy-nilly, has also stepped up his drinking of coffee to the point where it consumed almost the same portion of his waking hours that smoking had previously consumed.

Happily my friend is a man of moderate temperament so that his abandonment of the joys of the weed did not translate into an increase in more antisocial forms of behavior such as wife-beating, philandering or the abuse of controlled substances. But, as a matter of intellectual interest and to provide empirical underpinnings for his theory, we undertook a quick survey of people we had known or read about who had curbed one or another form of over-indulgence. Our researches confirmed, well within the scientifically acceptable margins of error, just what Pugh had conjectured: Each and everyone of them had, sooner or later, substituted one or more new vices which -- if weighted on a scale of seriousness of consequence that seemed to us sensible -- offset the vice abandoned.

Each individual, of course, is born with his or her own distinctive IVQ. And substitution weights may vary among individuals as well (one person may, for example, have to substitute far larger quantities of alcohol or hot fudge or illicit lovers to offset the loss of a daily pack of cigarettes than another of less nicotine-prone constitution.) There is also some evidence (although the scientific community is still sharply divided on this issue) that the individual's IVQ tends to decline with the onset of late middle-age. But for each individual, and for a society as a whole at any point in time, the body of available evidence suggests that the removal of one source of vice will only translate, perhaps after some lag for adjustment, into another widespread form of vice.

Indeed, my colleague, Curt Suplee postulates that the validity of the IVQ hypothesis has been amply demonstrated by earlier shifts in American cultural behavior. (See graph.) If we apply Occam's law of parsimony in the choice of explanatory variables, what can so simply and satisfactorily explain the rise of pornography in this country as the concommitant disappearance of spitoons? What but the sharp drop in per-capita consumption of lard could so well explain the skyrocketing of the U.S. divorce rate? And what is punk culture if not a displacement of teen-ager's lust for the sugar they lost in the diet soft drink deluge? Anyone who realizes that artificial sweeteners have driven adolescents to put safety pins through their cheeks can only shudder at the consequences that fat substitution can have for adult behavior.

So now you see the enormity of the decision that has been thrust upon the FDA -- an agency more habituated to the fine measurement of chemical and physical effects than to the weighing of ethical and social consequences. If the temptations of fat in all its manifestations -- from bacon-cheeseburgers to Sachertorte -- is no longer available to sate the human craving for sin and retribution, what ghastly indulgence of the flesh or spirit will arise to replace it?

Jodie Allen is an editor of Outlook