With health and weight consciousness all the rage, and diet after patented diet plan topping the bestseller list, the pressure on doctors and nutritionists to develop and christen original diet plans is formidable. The pressure has, in fact, extended to laymen, with the result that many a timely tome testifies to an expertise on food that consists wholly of a lifetime of eating it. The regimens published to date, however, possess a disconcerting uniformity. Though their focus may shift from starches to vegetables to proteins, the diets of the day display a consistent lack of imagination.

Not so the sensational new thematic diets. Designed with a motif in mind, these innovative weight-loss programs are divided into four basic categories. Because shared traits are the basis for selection of foods in the Denominator Diets, scientists, mathematicians, and other logical types are inclined to favor them. As might be expected, egalitarians and assorted activists are attracted to the Democratic Diets, pedants endorse the Didactic Diets, and connoisseurs of the cutting edge gravitate toward the Daredevil Diets.

Among the most interesting of the Denominator Diets are the Alphabet, the Chromatic, and the Decibel Diets. The Alphabet Diet is a 26-day plan restricting the weight watcher to foods whose names begin with a particular letter of the alphabet, beginning with "a" on the first day, "b" on the second, and so on, with abstinence prescribed for the 24th day (or ex-lax).

Day One
BREAKFAST
Apple turnover
Apple juice

LUNCH
Avocado salad
Alphabet soup (with Animal crackers)
Anchovy pizza
Apricot juice

DINNER
Antipasto
Artichoke, Asparagus, or Acorn squash
Alligator or Armadillo sauce piquant
Apple sauce, Almond ice cream, or Angel food cake
Amaretto, Absinthe, or Anisette

Similarly, the Chromatic Diet limits the participant's daily intake to foods of a particular hue, with a liberality in the interpretation of shades permitted. The progression from day to day is not ordained, as in the Alphabet Diet, but prismatic, or rainbow, order is recommended.

Red Day

BREAKFAST
Apple
Bacon
Tomato juice

LUNCH
Corned beef or blood pudding
Radishes
Cranberry juice

DINNER
Steak (rare!) or Red snapper
Beets
Red wine
Cherries jubilee or Strawberry shortcake

The foods eaten in the course of the Decibel Diet are selected according to the degree of noise they produce while being eaten. Of the two types of Decibel Diets, the "Loud One" -- consisting of such outspoken fare as Cheetos, celery, fried pork skins, apples, bagel chips, and Rice Krispies -- is generally favored by the actual participants, while the "Silent One" -- ice cream, mashed potatoes, etc. -- is more popular among neighbors and family members.

The Democratic Diets recognize the underlying political aspect of eating and encourage adherents to "make a statement" with each meal. The most common of democratic dieters is, of course, the vegetarian, who deletes meat from his daily fare to protest the slaughter of animals. His counterpart is the carnivore, who eliminates vegetables from his repasts to protest the abuse of plants, or, in reactionary cases, to disconcert vegetarians. Sympathizers of the migrant worker pursue a grapeless diet, while symbol-sensitive anti-nuclear partisans forgo mushrooms.

Among the most humanitarian of the democratic regimens is the Homeless Diet, which allows the privileged dieter -- and who but the privileged can afford the luxury of a diet? -- to see how the other half lives by restricting his menu to the contents of public waste receptacles. This diet should be pursued for short periods only, so as not to put an undue strain on the natural food supply of the true vagrant.

For proclaiming solidarity with the animal kingdom, no better program exists than the Fodder Diet, by means of which a dieter can enter the psyches of household pets and livestock via their stomachs and, if he allots himself similar portions, achieve substantial weight loss.

A sample week:

Sunday -- One bowl Meow Mix

Monday -- Two Gainesburgers

Tuesday -- One saucer of milk

Wednesday -- --- One pound of suet

Thursday -- Three fish pellets

Friday -- One bale of hay

Saturday -- Table scraps

At last there's an alternative for overweight postgraduates contemplating enrollment in health spas and adult extension curricula. Whether they opt for the Historical, the Detente, or the Berlitz Diets, the overfed and overeducated will enjoy significant weight loss and unique learning experiences with the Didactic Diets. The Historical Diet has particular appeal for antiquarians, who eagerly accept the stipulation that hey eat only foods that nobody eats anymore, foods that have gone the way of tunics and knee breeches.

For example:

BREAKFAST
Curds and whey

LUNCH
Gruel with treacle
Grog

DINNER
Pease pudding
Manna Mead

The Detente Diet brings to the world of food the philosophy of international diplomacy in that it requires the culinary Kissinger to join together in one meal foods that have maintained animosity for each other for centuries -- foods, in short, that don't go together. For dinner, one might begin negotiations with a cream of grapefruit soup, achieve a compromise between potato salad and peanut butter, reconcile hot dogs with chocolate sauce, and make peace between ice cream and oyster dressing.

The Berlitz Diet is based on the Platonic premise that weight increase is caused by the idea of food and not by food itself. A person gains weight not because he eats a dozen glazed doughnuts every morning but, rather, because he knows that they are glazed doughnuts, an idea carrying with it the notion of weight increase. Therefore, the practitioner of the Berlitz Diet is allowed to continue eating whatever he is accustomed to eating, provided he refers to it in a foreign language of which he is completely ignorant -- the theory being that, if he doesn't know what a beignet is, it won't hurt him if he eats douze or vingt-quatre.

The forerunner of the Daredevil Diets, the Novelty Diet was developed as a remedy for dieter's doldrums, the ennui experienced by the veteran dieter upon discovering that he has exhausted the supply of reduction plans on the market and is obliged to repeat one he has previously sampled. The Novelty Diet limits its practitioner to foods he has never eaten before and is thus guaranteed to renew his interest in weight loss. Of course, the more worldly his palate, the sooner his interest will wane.

The Container Diet has the advantage of allowing the consumer to maintain his current purchasing habits. He must reverse his thinking when it comes time for consumption, however, discarding the contents and devouring the packages they came in, thus enjoying the satisfaction of purchasing his favorite foods without suffering the unwanted calories acquired by eating them. Though they fail to provide the minimum daily requirements of vitamins and iron, doughnut boxes, Pepsi cartons, butter tubs, and cellophane are low in calories and free of cholesterol. They are also likely to have fewer additives than the foods they contain. Followers of the Container Diet can also pride themselves on their contribution to the anti-litter campaign.

Another daredevil regimen allowing the weight watcher to indulge in his favorite foods, figuratively at least, is the Polaroid Diet, whereby photographs of appetizing foods -- whether torn from the pages of women's magazines or captured instamatically -- are substituted for their calorie-carrying originals. This diet plan is ideally suited for the glutton in that an 8 X 10 chocolate mousse is no more fattening than a wallet-size one.

The Allan Bloom Diet charges the practitioner to remain open-minded as he consumes items not customarily regarded as food, due to longstanding cultural biases -- paint brushes, flea collars, cordless phones, and the like. Besides garnering the participant a citation in the Guiness Book of World Records, the Allan Bloom Diet is also guaranteed to reduce the frequency of garage sales.

Necessarily last among the daredevil regimens is the Socratic Diet, which, except in cases of extreme tolerance, provides for one meal only, consisting of a toxic substance chosen by a coterie of the dieter's enemies. Endorsed by Dr. Kevorkian and the late Jim Jones, the plan guarantees permanent and total weight loss.