probably someone on a diet -- once said: all advice is bad, but good advice is worse.

The day the National Institutes of Health panel came out with the not exactly earth-shattering news that being overweight is unhealthy at best and, at worst, downright deadly, I got a card from a friend of mine. On the front it said: "My weight is always perfect for my height." Inside it said: ". . . which varies."

My friends and I are veteran soldiers in the battle of the bulge. Perception at the moment seems to be that I am closer to winning than they. True, in the past three years I have lost 90 pounds. But the simplicity of that statement belies the real circumstances surrounding it.

For more than two of the past three years I had a vision of myself on the day I reached my desired weight. Seized by an overwhelming and unparalleled joy, I would . . . what? Take out a full page ad in The Post? Turn cartwheels down the middle of Constitution Avenue? Get arrested for standing naked in the window at I. Magnin?

Well, surprise, friends and neighbors. Of all the emotions I have experienced during this process, joy has never been one of them. Rather, I am like the circus performer who climbs slowly and inexorably up a tiny, ridiculously high ladder, just to get to a tightrope. The difference is he or she gets to come down, while I am here for the duration -- a large sausage pizza held high in my right hand and two heads of lettuce in my left.

So while everybody is passing out warnings to those estimated 34 million overweight Americans, I'd like to add one of my own: Come up at your own risk.

I am often amused (and more often angered) by the ease with which doctors and other experts talk about dieting, as if it were some sort of involuntary muscle reaction, like blinking.

The article that appeared in these pages a few months ago was typical: much discussion of the dreaded diseases that await us as we waddle through life, and of the prejudices we face in a world where fat is about as popular as a porcupine at a nudists convention, and even some discussion of the composition, color and presumed disposition of the individual fat cell.

So why don't doctors ever discuss dieting -- not obesity, but actual dieting? Well, a completely unscientific survey has yielded the following results. Fifty percent of all doctors are thin and always have been. In short, they can't talk about something about which they know bumpkins. Which leaves the other 50 percent, who have been or are overweight and have probably dieted. So why aren't they talking either?

Because they're afraid. They're afraid that if they told us the truth about the never-ending, constantly uphill, psychologically draining, hopelessly frustrating task that is serious dieting, we, in our infinite wisdom, would carefully and realistically evaluate the situation and our chances of lasting success and decide that the cure is worse than any potential disease.

I remember a Weight Watchers meeting I went to. (It was either the third or fourth time I had "rejoined.") The instructor said that on the Weight Watchers "program" (they don't like to call it a diet -- but like the man said, if it looks like a duck, and walks like a duck and quacks like a duck . . .), one should never feel deprived. I nearly had a rupture. The "D" in diet stands for deprivation, not to mention disillusionment and no small amount of depression. In exchange for the much-heralded joys of good health, you agree to give up no small measure of your sanity and an even larger measure of freedom.

And I might add that I've heard all I care to about the virtues and rewards of moderation. But since I cannot give up food entirely, I maintain moderation by not eating the foods I enjoy most or by eating them in such small quantities as to make it hardly worth the effort. Willpower is nothing more than a thoroughly unpleasant In fact, the road to good health is paved with dull, tasteless food. adjustment to a depressing reality, which is why I understand those people who simply cannot, regardless of the supposed rewards, cope with the "fat fighting system" as currently marketed by the medical community and half the magazines in the drug store.

The truth is medical science is moving in the wrong direction. With some generous assistance from the boys and girls up on Madison Avenue, it is attempting to brainwash us into believing that being healthy, however desirable, is also interesting and stimulating. In fact, the road to good health is paved with dull, tasteless food; endless, repetitive, boring exercise; and general, if not total, abstinence from any and all substances that make life -- even a shortened one -- worth living. Why isn't somebody researching ways to make the things that normal people love to do (or eat or drink) a little less deadly?

It all boils down to a question of percentages, and of just how much you and I as individuals are willing to sacrifice to have those percentages on our side. Suppose someone came to you tommorrow and offered you a choice: You can die at 65 of a heart attack partially induced by too little exercise and too many Italian entrees and French desserts, or you can live to be 100 and die of old age, with the lingering taste of low-fat cottage cheese in your mouth. Well, I'm not sure which I would choose. But there's one thing I am sure of.

I hate cottage cheese.