AS WE ALL know to our joy or sorrow, food speaks to more than the legitimate hungers of a body needing protein, fiber and the odd crumb of phosphorus or zinc. Food gratifies physical appetites distorted by quirks of individual psychology and social custom. It answers cravings of the soul.

It's among life's supreme pleasures. The first we know anything about. The last to go.

It's also an ever-present hobgoblin, poisoning people's tranquility with fear and guilt. There are human beings who are more thoroughly intimidated by the mere thought of a hot fudge sundae than by a phone call from the IRS. Honest citizens have suffered greater remorse over what they did at the buffet table than over indiscretions in the boudoir. Some have even been scared off drink because of the way an extra glass of wine can lower inhibitions about the chevre and brie.

Almost everybody has some experience with compulsive eating. Who doesn't recognize the jerky rhythm of Candice Bergen's Frito-munching when, in "Rich and Famous," she waits for her husband and her best friend to come back from an over-long walk on the beach?

Compulsive eating is firmly established as a laughing matter. Witness Popeye's Wimpy snarfing hamburgers, or Blondie's Dagwood piling up a midnight sandwich. Dom De Luise has movie audiences roaring when he greets the sight of a bakery with a leer and the words "I need a pie."

In real life, though, Dom De Luise doesn't find compulsive eating funny. He is one of the people to whom food has become less a pleasure than a tyrannous addiction.

Some don't fight it. Shakespeare showed us a supreme example of the personality type that neither passes up nor postpones any satisfaction the most primitive impulse demands. His Falstaff not only eats, drinks and wenches whenever he gets the chance but also lies, brags and runs away from danger. He buys conviviality, if not friendship, by giving other people both a reason to feel morally superior and an excuse for behaving the way he does.

Falstaff's adjustment is only one of many devious strategies for coping with the difficulty we all have in saying no when we want something. Some surrender to food and make fat the alibi for failures in work and personal relations. Some diet to the point of starving themselves.

Such are the convolutions of human psychology that the self-denying ones sometimes achieve a voluptuous sense of power in governing their appetites. Politics shows us extreme examples of how fasting can be manipulated by power-seekers.

Hunger strikes were routine gestures for Emmeline Pankhurst and the other British suffragists in the early years of the 20th century. Mahatma Gandhi used fasting with great effect as a weapon against the British in the struggle to free India. Contemporary IRA prisoners in Northern Ireland have fasted with less political impact but more tragic personal consequences.

These days, biochemists, psychologists and political activists are equally interested in obsessive eating. The biochemists are discovering physical reasons why eating large quantities of sugar and carbohydrates creates cravings for more. It seems there is something special going on among the elements up there in the brain that makes people feel better when they take on a sticky bun. In quest of control devices, they are exploring hidden allergies and nutritional deficiencies that may trigger food binges.

Meanwhile, the psychologists are probing the nonchemical motivations of compulsive eaters. As they look back on childhood memories of reward and punishment to find the reasons why gorging on chocolate cake seems to stifle fear and anger for some people, they are experimenting with behavior modification techniques to break their patients' self-destructive habits.

Certain feminists have other interpretations of women whose eating is out of control. They relate their inability to manage this aspect of their lives to the theory that a male-dominated society has deprived them of the experience of power. They also call it a rebellion against a male-dominated society's standards of how a woman should look. Thin.

The bad news is that few people, in or out of formal programs designed to stop overeating, manage to curb their unhappy desires permanently. The better news is that more and more approaches are being tried.

Besides such commercial organizations as Weight Watchers, the fat farms and the diet workshops, there are serious research and treatment centers, such as the Georgetown Medical School's Diet Management Clinic, which deal with anorexics -- the compulsive noneaters -- as well as the people who can't stop stuffing. For people who abuse themselves with food, there is Overeaters Anonymous, which relies on some of same techniques used with those who abuse themselves with alcohol.

Perhaps the best news is that efforts are now being made to rescue children from compulsive overeating. Children's Hospital now sponsors two informal therapy groups in which 10- to 16-year-olds can learn the rules of nutrition and can help each other replace harmful eating habits with sound ones.

A prospect worthy of thanksgiving. At least it would be if the word were not synonymous with overeating.