HEREIN is the most grotesque sort of debauchery, growing only gradually out of an urbane but decadent sensuality. Gourmet sophisticates become maniacal gluttons; a plump school teacher becomes a ravenous Rubensian voluptuary. The characters are, for the most part, reluctant even to talk about the secret of their gathering--that they have come as suicides. Gradually, their festival of grand cuisine dissolves in a death-charged, sex-charged bacchanal.

Four men have arranged a weekend of undisturbed eating at a fenced-in country house once owned by the classical poet Boileau-Despreaux. Their arrival is followed by the arrival of the meat truck bearing wild boar, lamb, beef. Each carcass is ceremoniously described: "Three dozen young Ardennes roosters...two superb, soft-eyed deer, the flesh redolent...ten dozen semi-wild game hens."

Wearing bright orange rubber gloves that extend just past the French cuffs of his delicate shirt, Michel Piccoli lifts the head of a slaughtered calf high above his own head. "To be, or not to be," he screams in a shrill voice. Ugo Tognazzi makes a loud farting noise, tongue between his lips, and the feast begins. Kidneys bourguinon. Kidneys bordelaise. Crayfish a la Mozart. Each dish has an identity of its own, but the diners ignore all subtlety in order to concentrate more conscientiously on their suicidal quest. Marcello Mastroianni stuffs down six clams in one bite. Grubby fingers and grubby mouths attack roasted legs of fowl so greedily they would make Henry VIII blush.

EATING BECOMES A LEWD act. Mastroianni, however, longs for real sex, so he calls for his tarts. One of these whores throws herself naked on a cake; sex and eating become one and the same. Except in that director Marco Ferreri depicts eating in complete pornographic detail while restricting his portrayal of sex to angles and acts which coyly protect his male stars and are well within the soft-core boundaries of major studio productions.

Ferreri follows a straightforward method: He begins with decadence, then pushes it to its extreme. His timing is exact, always cutting away from a scene once depravity is well established, never carrying on for the sake of prurience. Followed properly, this method would shock, never titillate, but the double standards of soft-core pornography weaken The Grande Bouffe. The simulated sex becomes funny in otherwise serious scenes. The film leads from abuse of food to abuse of bodies, but the bodies are less real than the food, so the progression falls flat. A similar problem occurs in suggesting Michel Piccoli's gastric disturbances by loud, artificial noises on the soundtrack. In both sex and scatology, The Grand Bouffe is curiously tentative and embarrassed even when it exaggerates.

THE CONFUSION caused by these half-way measures has been typical of commercial sex films in recent years, and is the main reason the films themselves are decadent. One film after another breaks what seems to be new ground, taking one more hesitant step in the direction of completely free expression. The emphasis on novelty which this process entails creates a strong gulf between a natural expression of sex and the overly bawdy or overly arty films that actually get made. Last Tango in Paris, for example, is a film about decadence, but it becomes decadent itself only in its sex scenes, where filmmaker Bernardo Bertolucci, caught between discarded rules of decorum and unacceptable liberality, filmed simulations and dirty jokes. The petty sex scenes undercut the excellence of the rest of the film.

The Grande Bouffe, like Last Tango in Paris, is a vision of life burning itself out, but in The Grande Bouffe there is no romantic illusion, no disguised depravity. Ferreri makes his points in terms of acting instead of camerawork and soundtrack. The performances he elicits are often remarkable--particularly the outstanding performance of Andrea Ferreol as the teacher who joins the group--and they are well emphasized by the simplicity of his direction. But he is a neutral observer, unlike Bertolucci, unable to make the impact of events accumulate. Weakened by pseudo sex and juvenile scenes about car fetishes, the film becomes diffuse.

Ferreri's greatest problem, however, is that he fails to connect the everyday lives of his characters with their actions at the villa. In the opening scenes, he gives a glimpse of each man's life, but the vignettes connect only superfluous details to the body of the film. This is a film about a decision to die, about a decision by four well-to-do-men that bizarre death on the weekend is somehow worth more than a less frantic hedonism continued over a protracted period. The decision to die cannot be divorced from the work and family lives of these men. Living is not such an easy habit to break, even for a good meal.