I KNEW THE time had come, when I realized that people seldom asked me anymore how I keep so slim. Even under the best of circumstances, dieting is difficult--or at least unpleasant. But when your job is eating and then communicating the allure of food, it becomes something akin to Ulysses confronting the Sirens. I need my hands tied behind my back.

Excuses beckon: I can't just order a salad with a wedge of lemon, because I must evaluate what the public is interested in eating (fried onion rings). The dieter's ploy of eating only a bite or two won't work for me; to appreciate all the nuances of the tournedos Henri IV, one must taste several bites -- or the whole thing -- for ultimate accuracy. And a restaurant critic needs to sample the bread, not to mention the tarts and the sorbets and the whipped cream (the reality of the kitchen, after all, often lives or dies in the whipped cream). Furthermore, the reason I am a restaurant critic is that I love food, am intrigued by its variations, am obsessed by its art. How, then, do I remain indifferent to its call after a meager taste that has merely awakened my dormant hunger?

Finally, I cannot simply not eat when I am not hungry. There are recipes to be tested, tastings to attend, a full schedule of restaurants to review. Food is my work as well as my play.

Holiday time, I realized, had to be seized as a chance for a holiday from eating. While I recognized that it was only fantasy to try to lose pounds and inches in the snowy banks of Vermont while I enjoyed exploring country inns with my family, I could at least hold steady and perhaps reverse the trend with a couple of discarded grams.

We set off north, five people, four pairs of skis and a suitcase full of research notes (for me it was a working holiday). I had packed the family a pile of sandwiches and the leftovers from our refrigerator, not to mention the cookies and two-pound box of Godiva chocolates we had been given as gifts. For all of us, there were carrot sticks and fruits. For me alone, a half sandwich (lettuce and tomato with a few slivers of cheese) and my special treat: an enormous bag of popcorn popped without oil to keep me company through long days of writing about food.

I also carried with me a few hard-earned lessons:

* Starvation, I knew, was not the answer; rather, the task was to plan my eating, and to include a treat that was low in calories but would satisfy the need to munch that which accompanies holiday relaxation.

* Trying to keep to a diet of specific menus -- Scarsdale, for instance -- was too complicated on a trip through ski country. And I wanted leeway to taste the specialties of inns we would visit. So my theme was low-fat foods and small tastes of forbidden delicacies.

* A gimmick: I aimed to start meals, whenever possible, with a bowl of clear soup. Not only does that allow me to keep busy at a long restaurant meal by consuming calories at a slow rate, but it gives my appetite time to signal that it has been appeased.

* I also had to take into account my lifelong membership in the clean-plate club. So I attempted to order enough to satisfy apre's-ski-hungry teen-agers but not so much that I would be tempted to finish off the pa te' or the chestnut pure'e. Since we are a family of plate passers and sharers, that meant ordering, most times, four main courses for five people. Thus my maternal instinct -- to stuff my children while bathing in the glow of self denial -- could conquer my plate-cleaning inclination. The clear soup, however, was all mine. And, surprisingly enough, for the first time in their lives, my children coveted consomme'. I wondered whether the ploy would work with turnips.

Applying these principles started out to be easy, at least that first evening at the Four Columns Inn at Newfane, Vt. Duck broth with noodles turned restraint into a blessing. It was far more exciting than the cream of carrot soup I passed up. Scallops and shrimp nic,oise, in a light and fresh tomato sauce with basil and orange zest (I put the olives on somebody else's plate) bolstered my resolve -- this diet was a cinch. In fact, a treat. The good, crusty bread was fine without butter. One bite of duck breast with lime or veal with mushrooms and cream were enough, as long as I had my delicious seafood to return to. The great problem was the salad; I had forgotten to ask for it without dressing, and it was a particularly good blend of boston lettuce with garlic and herbs with plenty of olive oil. It took considerable will to pass it to somebody else to finish.

I also had to tackle the issue of wine. Few restaurants have an interesting choice of half bottles or of wines by the glass. Thus I needed to find techniques for drinking my wine slowly enough to avoid the temptation of refilling my glass from the unfinished bottle. The first part of the meal, I merely swirled and sniffed the wine; never have I attended more closely to a wine's bouquet. And thereafter, I took only occasional sips, more often smelling than tasting. One certainly gets full value from the wine this way.

Buffet breakfast, now there's a trial for a dieter. The Chester Inn in Chester, Vt., was a tough exam. It took full wakefulness to withstand the bacon aroma and banana muffins. Since there was no toast available, I limited myself to pancakes -- plain, thinking of them as bread -- and orange juice. Lunch in the room was fruit, plus popcorn to satisfy the inevitable need to munch while writing about food.

But the test that is hardest to pass is a holiday meal. And I certainly didn't pass with flying colors. At Christmas Eve dinner -- a buffet served by Santa Claus, no less -- it was impossible to refuse a slice of suckling pig, the venison stew, a dab of bearnaise on the roast beef, a spoonful of apple stuffing. Weighting my plate with cauliflower and three-bean salad helped slightly. After that, I felt too guilty even to consider dessert, and I kept away from the eggnog, cookies and carol singing in the bar. Christmas morning the rest of the family opened stockings full of ski snacks, while my daughter surprised me with two apples and a tiny but highly caloric sampler package of macadamia nuts. In gratitude and self interest I shared them with her.

Popcorn had become my solace and treasure.

To get through the course, I had to remind myself occasionally that one failing grade is not a reason to give up. There were days left for recouping. I was ordering modest portions, remembering to ask for my salad without dressing, swirling and sniffing my single glass of wine. It took Christmas dinner at Stowe's Inn at the Mountain to remind me to ask for my fish broiled without butter. Fish was becoming my staple, along with whatever vegetables and fruits seemed neither heavily buttered nor sugared.

The next crisis came one evening when a dressing-free chef's salad with most of the ham and cheese doled out to my table companions left me hungry and depressed. That was when I learned to drown my troubles in a Virgin Mary. Few calories, lots of spice to make my taste buds feel fed (and in some cases to numb them) and a long time in the consumption -- this alcohol-free cocktail pepped me up, reminded me of more carefree meals. And it was available in every hamburger joint or hollandaise-drenched inn.

It was only after a week of returning to my old habits -- sampling the full range of a restaurant menu twice a day -- that I could weigh myself to find that what I did on my Christmas vacation was lose half a pound. As all those nice friends around me pointed out, at least I hadn't gained weight.

My restraint was, as I looked back on it, more hard work than deprivation. By the end of the diet holiday, I had learned to limit caloric escapades to one bite when they were a matter of tasting someone else's food, but had not yet managed to stop myself at half a portion of the plate in front of me.

I probably need another holiday to learn how to push away my plate with half of it left unfinished. I hear, for example, that the Caribbean is a good place to diet at this time of year.