Members of his department have a constitutional right to be fat, Prince George's Sheriff Don E. Ansell suggested yesterday in responding to a grand jury finding that most of his deputies are "obese, undereducated and untrained."

"The surgeon general of the United States," the sheriff told reporters gathered at the county office building yesterday for what was billed as a press conference, "has determined that the majority of the American public is legally obese, and common sense dictates (that) obesity is no more disqualifying than a person's race, color or creed."

Ansell rejected the other characterizations of his men as untrained and undereducated. Of 270 deputies, he said, 35 have colleges degrees 77 have had some college education, and 99 possess high school diplomas. To underscore the point, an Ansell aide distributed pictures of deputies listening intently to an instructor during an "in-service" training course.

The sheriff, his honesty and adminstration both called into question last week by the county and grand jury, chose not to discuss his indictment for alleged misappropriation of funds, lying to a grand jury and filing a fraudulent state tax return. Nor would he answer reporters' questions:

Instead, bathed in television kleig lights in the County Council chambers. Ansell read a lengthly statement aimed at countering the grand jury's separate noncriminal indictment of his administration.

Ansell noted but did not address the grand jury's finding of "favoritism, cronyism and nepotism" in his administration.

He flatly denied the panel's assertion that "pilfering, lying, cheating and misuse of (jail) trustees for personal gain exists" in the department. His proof. Ansell said, is "the failure of the grand jury to indict members of the sheriff's department for malfeasance occasioned by pilfering, lying and etc."

The report, Ansell said, was "replete with self adoration an platitude, patently erroneous facts, subjective value judgements, and the most slanderous, impertinent and irrelevant remarks." In contrast, he said, his reponse yesterday contained, "no subjective statements or value judgements."

Jon M. Hill III, a real estate salesman who was the grand jury foreman, said, "The sheriff didn't quite read our report as well as he should have."

As for Ansell's criminal indictment, Hill volunteered. "Seriously, I do think he's a fine gentleman and I hope he's found innocent, but the evidence does indicate probable cause to believe that a crime was committed."

The sheriff, accompanied by his wife Frances and Guy T. Williams, the assistant sheriff indicted with Ansell in the alleged misappropriation scheme, said the grand jury was correct "that morale throughout the department is at a low" and that bickering and in fighting has in fact become a day-to-day problem."

Uncertainty caused by the imminent creation of a new county corrections department, which will severly reduce the sheriff's department payroll, is the cause of the morale problem, he said. "Deputies simply do not know what the future holds for them." Ansell said.

Several deputies, however - all vocal critics of Ansell who cooperated with prosecutors and the grand jury probe - say they fear retaliation by the sheriff as the greatest threat to their future. Many wish to remain sheriffs deputies rather than become corrections officers.

Donald Weinberg, county personnel director, said it si not yet clear who will decide the deputies future in any personnel shift caused by the creation of the new departmet.

The potential for retaliation by an indicted sheriff is "a concern" he said.

Who gets to stay in the sheriff's office. Ansell said, "is a matter between the deuties and I (which) I will take up at a later time."