Although Ronald Reagan has put Uncle Sam on a diet, the government still hires nearly 700 people--from plumbers to physicists--every working day.

The Defense establishment--Army, Navy, Air Force--is doing most of the hiring. Many other agencies are just replacing workers who quit or retire, or are cutting jobs through attrition or RIFs. Nearly 90,000 of metro Washington's 345,000 feds are in Defense.

Since the president took office the agency doing the most hiring is Army. It signed up 17,200 workers through February of this year.

Navy welcomed 11,000 civilians aboard between January 1981 and February 1982. Air Force hired 9,700 civilians.

Employment at the Defense Logistics Agency is up 2,000. Overall employment in all Defense-related units was up 41,351 during the period.

During the same time frame most civilian agencies were shrinking through attrition (for a net loss of 51,180 jobs). Biggest losers were:

Justice, down 2,300 jobs; Interior, 5,600 positions; Agriculture, 6,400; Commerce, 12,000; Labor, 3,400; Health and Human Services, 9,700; Transportation, 10,200; Housing and Urban Development, 1,600; Energy, 2,900; Education, 1,600.

Among independent agencies the job drop was 2,300 at Environmental Protection Agency; 545 at the Equal Employment Opportunity Commission; 667 at the Federal Emergency Management Administration; nearly 5,000 at General Services Administration; almost 300 at International Communication Agency; 995 at the National Aeronautics and Space Administration; 1,200 at the Office of Personnel Management; 886 at the Small Business Administration; 6,200 at Tennessee Valley Authority and 2,400 at Veterans Administration.

Gainers during the January 1981 to February 1982 period were the State Department, up 237; Nuclear Regulatory Commission, 236 and the U.S. Postal Service, up 8,400.

Knowing the recent hiring practices is helpful to job-hunters, and keeping up with the news--program changes ordered by Congress or the president--can be a tipoff as to who will be hiring in the future, and who won't as well as the kinds of people government is looking for. Social workers, for instance, are out. Engineers and secretaries are in demand.

Bear in mind that the numbers, like all statistics, can be deceptive.

Most of the big job drop at Transportation, for example, came from the 11,000 air traffic controllers fired last August. The Federal Aviation Administration is beating the bushes for replacements.

Just recently, places like Justice, Agriculture and VA, where it was chop-chop all last year, have begun hiring again, in a small way.

Employment at Agriculture, for example, went up nearly 300 jobs from January to February of this year, VA hired 661 people during that period. Most of the other increases were small, but indicate some growth.

HUD and Energy are considering further job cuts. And Energy and Department of Education are on the administration hit list.

Contracting out plans in agencies like GSA and Defense could mean cutbacks in civil service employment. But costs will be passed on to the taxpayers even as they read happily about further reductions in the number of "bureaucrats."

Deciphering the federal job market is so tough it has created a new industry: firms specializing in telling individuals, and agencies that are hiring while also trying to place fired workers, where the jobs are.