Twelve years after she saw the light, 2 million copies after her first book on the subject, Frances Moore Lappe finally got to tell Congress about her view of world hunger.

Lappe's view is beguilingly simple: the world produces enough food to feed itself, but waste, politics and misguided economics keep it from doing so.

The message doesn't much ripple the water on Capitol Hill (only two House Agriculture subcommittee members showed up to hear Lappe at a hearing last month). But in hungrier precincts her thoughts are treated as Olympian wisdom.

Through her writing and her work with the Institute for Food and Development Policy, a San Francisco think-tank that she and Dr. Joseph Collins founded, Lappe has a large following here and in developing countries.

The institute is one of a growing number of public-interest and advocacy organizations delving into food policy and agricultural economics. In one way or another, all urge changes in growing and marketing procedures to protect land resources and feed more people.

The National Farmers Union and the American Agriculture Movement often follow similar lines of thought and action, reflecting farmers' discontent over government policy and trading companies' control of global grain marketing.

The high priestess of the movement is Frances Lappe (pronounced la-PAY), who created her first waves in 1971 with "Diet for a Small Planet," a provocative polemic and high-protein, meatless recipe book. It was an instant success, and with printings at 2 million copies in seven languages, a 10th anniversary edition is in the works.

The theme is that grains and legumes, if prepared with imagination, can be eaten directly with far more nutritional efficiency than by converting them to meat through livestock, a process that consumes huge amounts of the world's basic grains.

Lappe picked up a reputation as "the Julia Child of the soybean circuit," because of her frequent television appearances stirring a pot of high-protein beans and plugging her book.

But the air of frivolity vanished with her next work, "Food First: Beyond the Myth of Scarcity," which she and Collins coauthored. That volume, also available in a half-dozen languages, is used widely for reference and discussion by churches, colleges and labor organizations.

Since then, the institute, a low-budget operation set up in 1975, has continued food studies and published a number of pamphlets and booklets directed at stimulating agricultural policy changes here and abroad so that farm resources are protected and more hungry people are fed.

"We are not just trying to educate," Lappe said recently. "We are trying to awaken people. We are trying to demystify the power of those who have all the statistics under their belts. They use the fear of change to continue the system as it is today."

Lappe's own awakening occurred in 1969 when she quit her job as a community organizer in Philadelphia in frustration. She wasn't making a difference. "I decided to stop trying to save the world until I understood it more," she said.

She decided that food was basic and, following her nose, as she puts it, she read and asked questions extensively. She concluded, contrary to what the headlines were telling her, that overpopulation was not the cause of world hunger and malnutrition: the causes were misuse and maldistribution, politics and economics.

"It's difficult to keep from being red-baited," she said, "but we are focusing on the concentration of control over our food-production systems. We are trying to draw out the basic fears and misconceptions, help Americans see that power is not a dirty word. People have the power to change the system."