THE SHORTCOMINGS of John Huston's Fat City notwithstanding: it is a movie that tries very hard to succeed. The dialogue is sensitively written. The acting is generally excellent, and Huston's direction has created a remarkably realistic film about people caught in a web of self-deception and defeat. Unfortunately the audience never becomes totally immersed in this world. Despite the thoughtful porrayal of virtually every major and minor character, weaknesses in the development of the plot dampen the overall impact of the picture.

Though the movie deals with boxing, the violence on which it focuses is not the brutalization of the body but the devastation of the human spirit. It centers on Billy Tully, an overaged boxer whose psychological survival depends on a comeback he cannot rationally hope to accomplish. After a year-and-a-half away from the ring, he succeeds only in beating a washed-up Mexican fighter for a $100 purse. Within a year, he is outshined by his own protege, an eighteen-year-old youngster with no previous experience, who has the strength and the discipline Tully will never regain.

Stacy Keach is outstanding in his performance as Tully, turning the pitifully flat character into a provocative and sympathetic figure. Jeff Bridges succeeds less as the young boxer, Ernie, but only because his role is so badly underdeveloped. In a few scenes with his girlfriend, he is given depth and personality of his own. Most of the time, his motivations are completely uncertain. Ernie has been conceived as a foil for Tully, and their relationship exists chiefly to reveal more of the older man's character.

A major strength of Fat City lies in the performances of its supporting players. As Oma. Tully's alcoholic girlfriend. Susan Tyrell slightly overdoes her part. She still succeeds, however, in projecting a child-like vulnerability and a profound sadness in her attempt to bolster an almost non-existent self-respect. Oma's black lover whom Tully temporarily displaces, Reuben, Tully's manager, and the other boxers and trainers are all excellent in their roles. Despite the small material each has to play with, they rise beyond the level of caricature to enliven the grim and unrewarding world that the movie portrays.

THE MOST IMPORTANT asset of the film is the writer's and director's understanding of each character's emotional crises. Larry Gardner, who wrote both the screenplay and the original book, does better exploring the subtleties of some of the individuals he has created than he does interweaving his many characters into a plot. Using Gardner's ingredients, with his own perceptive eye for descriptive detail, John Huston accentuates the actors' moods and emotions superbly. In one memorable scene, the fighters' reactions to a continually opening car trunk sharply underscore their excitement before driving to a match.

The boxing ring provides a perfect focus for the psychological concerns of Fat City. The sport's appeal to its audience consists largely in the opportunity it affords the spectator to project his own hostilities onto the aggressions of the fighters. Each contender can do what the spectator cannot: conquer his weaker opponent with sheer strength and agility in face-to-face combat before a crowd obligingly roaring its approval. It is also true that the fighters and managers use one another. Each boxer's value is proportional to the number of other boxers he can defeat. For the trainer, the fighter is an investment to be properly nurtured and exploited.

This gross manipulation mirrors a more subtle psychological process in which each character uses others to escape feeling his lack of self-fulfillment. Each person has the sense that with only the right break or the right handling, he might achieve recognition and acceptance as himself. Since this warped self-expression relies on other people's pain, the goal of attaining a genuine sense of self-importance is illusory for each of the characters. After a dismally amateurish fight against a boxer weakened by age and by earlier physical punishment, Tully finally wins a victory after two years of defeat and stagnation. Too dazed at first to even recognize that he has won, and so debt-ridden that he keeps almost none of his prize money, he not only fails to realize new self-respect: he does not even satisfy his most basic material needs.

Each of the characters is preoccupied with an illusion. For Reuben, Ernie represents the new "great white hope." With her lover. Oma feels that it is racial prejudice dragging her down: she avoids confronting the emptiness of the life she has created. Faye, Ernie's girlfriend, sees him as her vehicle toward the future: he is the means to escape the loneliness of her life. Ernie's dreams rest on his strength and on his hopes for Reuben's management. His shattered mentor, Tully, foreshadows the more likely end to Ernie's career.

THE CENTRAL QUEST for love and acceptance belongs to Billy Tully. Once the object of the crowds' adulation. Once married to a beautiful woman who deserted him when he started losing, he still carries the picture of his former wife in his wallet. To again have his stature and to literally possess this woman are the objects of Tully's persistent, but futile dreaming. All of the sadness of the movie is echoed in his words: "Some women love you for yourself, but it doesn't last long."

Fat City achieves an almost palpable mood of defeated loneliness that is tremendously moving and thought-provoking throughout. Sadly, its creation is never more than an atmosphere. We are never invited into, never engulfed by this world. To the end, Billy Tully, physically and emotionally battered, blames his failures on cheating fighters and on the negligence of his manager. From afar, we are left to speculate on his world of fear and jealousy: we learn that violence is more than absurd--it is tragic. But while we are permitted to reflect on his desperate illusions, we are never fully engaged in the actions in which he moves. We think about how deeply this wasted man has been wounded, but we are never so involved that we share in his pain.