BOSTON, OCT. 26 -- A study by the Physician Task Force on Hunger in America concludes that despite nearly five years of steady economic expansion, 20 million Americans -- especially infants, the elderly and former blue-collar workers who have dropped out of manufacturing into the service sector -- do not get enough to eat.

"The main point that we draw is that supply-side economics has failed as a remedy for hunger," said Larry Brown, a professor at the Harvard School of Public Health, which released the report.

The authors said economic growth "has not reduced hunger in any significant way . . . . The economic pie has gotten bigger, but the unevenness of that growth leaves millions falling further behind."

The report was based on field investigations in four regions: Texas and Louisiana, where the oil and natural gas industries are in decline; Minnesota and Iowa, where family farms are endangered; Pennsylvania, Ohio and West Virginia, where many high-paying steel and mining jobs have disappeared; and California's Silicon Valley, where service workers, including many immigrants, earn minimum wages amid the wealth of high technology.

The task force defines hunger as "chronic inadequate nutritional intake," based on the recommended daily allowances set by the National Academy of Sciences.

"People obviously aren't dropping like flies. The epidemiology is not like the Third World, where you go around and count bodies," Brown said. But "families miss meals, cut down, go without for a couple days. The typical profile is one fairly well-rounded meal a day." Often, over time, he said, "the children and even the adults suffer adverse health outcomes."

The authors derived their 20 million figure by reasoning that most of the 32.4 million Americans living at or below the official "poverty level" -- $9,096 a year for a family of four -- suffer chronic inadequacy in their diet because the poverty standard itself is based on food costs.

Martin Anderson, a domestic and economic policy adviser to President Reagan from 1981 to 1982, criticized the report on grounds there are no "official" figures on hunger. "Numbers like that are potentially misleading in the hands of nonexperts," he said, noting doctors, not economists, wrote the report.