If it weren't for Lean Cuisine, Le Menu and Banquet Gourmet, thousands more Americans might be out of work.

While jobs are rapidly disappearing each month in the oil and gas, steel, automobile and other manufacturing industries, jobs are sprouting in the gourmet frozen foods business. There also have been employment gains in chicken packaging -- because of the fowl's low-cholesterol benefits -- and in restaurants and bars.

But the employment rolls haven't been fed by chicken and gourmet frozen foods alone. Consumers also are spending on furniture, construction products, clothing, and medical, business and government services -- all of which have led to increases in employment by those providers, according to Labor Department figures.

Concern about unemployment has focused attention on the thousands of jobs that have been lost: 50,000 in the auto industry since early last year, for example, and more than 300,000 in total manufacturing since August 1984.

But many industries have been steadily adding workers, so that 109 million American civilians were employed last month, 3 million more than a year earlier.

"People eat," said James McVey, economist for the Labor Department. "So (employment) kind of stays on the even keel."

"Every time you look, everyone's coming up with 'light this' or 'pop-it-in-the-microwave that,' " McVey said. Chicken preparation, which has created 35,000 jobs since 1972, recently "has exploded," he said.

The net increase in jobs reflects the lopsided nature of current economic activity. Lower interest rates have led to a burst in housing sales and construction, resulting in more employment not only in real estate and construction, but also in businesses such as insurance, which are indirectly related. At the same time, the decline in oil prices has reduced the oil and gas industry work force by about one-third, and businesses that depend on it also are suffering.

Imports have hurt many manufacturers such as machinery, textile and apparel makers, while retailers and wholesalers that sell imports have expanded steadily, even through the last recession.

Demographics are responsible for some of the job creation. The large numbers of women who have joined the labor force, for example, have given new life to businesses such as child-care centers, frozen-food makers and restaurants, economists said.

In some fields -- for instance in the auto industry -- a decline in employment does not mean that the industry is doing badly, but that its use of high technology and robotics has made the business run more smoothly and economically. Labor costs generally are the highest expenses an employer must pay.

An example of an industry affected by a cyclical trend is the lumber and wood-products business, which has benefitted from the surge in construction fed by the reduction in interest rates in the past year. The lumber industry has grown by 24,000 jobs since May 1985.

The furniture industry, which also is linked to the interest-rate-induced growth in housing construction and sales, has added 7,000 workers. The stone, clay and glass products industry, which includes glass, cement, concrete, plaster, asbestos and other construction materials, has grown by 9,000 jobs after a slump several years earlier.

"Certainly, if the housing industry is doing well . . . you have to have furniture to go along with those houses," said Labor Department economist John Bregger. The lumber and furniture industries have regained all of the jobs lost during the 1981-82 recession, Bregger said -- an achievement, considering most manufacturers are still far below their prerecession employment levels.

Finance, insurance and real estate employment also has surged because of the housing boom, increasing by 346,000 since May 1985, the Labor Department said.

Although the manufacturers who make the goods are suffering, the wholesalers and retailers who sell the goods are not. They are thriving by selling imported products.

"Consumption has been high across the board," Bregger said.

Despite calls for smaller government, the federal, local and state work forces have increased steadily. "Government is a long-term growth industry," Bregger said; employment there has increased by about 400,000 in the past year.

Increased government employment may indicate "that the budget crises have eased across the country" and state and local governments can hire more workers, said Martin Baily, a Brookings Institution economist. A growing school-age population, meanwhile, is fueling the demand for more teachers, Baily said.

One issue with which economists have grappled is whether the loss of so much manufacturing employment while service industries have been adding workers means that the nation merely has traded high-wage jobs for low-wage jobs. Economists said it is not clear whether this is the case.

According to the Labor Department, the average hourly earnings of workers in manufacturing were $9.71 in may compared with $6.01 for those in retailing. Among the industries that have lost employment, steel paid $13.81 hourly and autos paid $13.59.

However, economists also note that people leaving manufacturing jobs often had not had enough seniority to earn the highest pay. Some manufacturing industries that have shed workers have low average hourly pay scales, such as $6.90 for textiles, $5.77 for apparel and $5.88 for leather products.

Workers in finance, insurance and real estate, on the other hand, earn an average of $8.29 an hour, and those in wholesaling make $9.30. Transportation and public utilities workers earn $11.57 an hour, and those in other services make $8.10 an hour.

Retailing, which has shown strong job growth, has average hourly earnings of $6.01, the third lowest of any Labor Department category.

A recent Labor Department staff study concluded that employment shifts likely will lead to an increasing proportion of workers in occupations with higher-than-average earnings and fewer in occupations with lower-than-average earnings.

For example, if the decline in the so-called smokestack industries -- iron, steel and autos -- had not occurred, "total employment in 1983 would have been only 0.5 percent higher" in those industries, the report said. "Even if all of these workers were in the middle third of the earnings structure," they represent such a small part of the total job force that overall distribution of workers by earnigns would not have changed much, the study said.

As for the loss of jobs in textile, apparel and leather-products manufacturing, the report said that because these industries pay relatively low wages, "The decline in the number of workers in the bottom of the earnings scale that resulted from their employment declines more than offset the decline in the higher-paying smokestack industries."

High-tech industries, which have added workers at a fast rate, have a greater proportion of highly paid workers than manufacturing industries do, the study said. However, they also have a higher proportion of low-paid clerical and service workers than manufacturing, the study found.

Baily said that many studies often combine wage data for part-time service workers with full-time service employes, which would tend to bring down their average wages and make it appear that service jobs pay more poorly than they actually do on a weekly or yearly basis.

Although many critics charge that the economy will become saturated with low-paid fast-food workers, Baily said many of those jobs are filled by people who want to work part time. "It's not clear that's such a terrible thing," he said.