Four women, all admittedly on the heavy side, applied for jobs here -- three as bus drivers and one as a subway car cleaner -- and were turned down by the state Mass Transit Administration. The reason: Each weighed between 186 and 205 pounds at the time they applied, exceeding MTA height-weight standards.

The rejection of the four job-seekers, which occurred between 1979 and 1983, is the subject of a novel and bitterly contested hearing unfolding before a hearing examiner of the Maryland Commission on Human Relations here.

The core questions are: Is obesity, like blindness or paralysis, a physical handicap? And is its cause cultural or inborn?

Lawyers and doctors, using technical and arcane language, have been groping for the last two days through untested concepts of "disease," "disorder," "causality" and their possible link with the key word "handicap."

The four women filed grievances with the human relations commission, contending that MTA violated state law barring employers from denying jobs to handicapped people when the handicap does not interfere with their work. Further, the women contend, they are not in fact handicapped but that MTA "regards or perceives" them as such, in violation of the law.

This week's hearing before hearing examiner Merry C. Hudson comes after years of preliminary legal wrangling by MTA and human relations commission attorneys and marks the first time an attempt has been made to include obesity on the list of physical handicaps recognized by state law.

Ironically, no one in the case, including the four women, says they are in fact handicapped. But the different factions have different reasons.

"I don't feel my weight is a handicap," said Jacqueline Tolson, who now weighs 170, in an interview yesterday during a break in the hearing. ". . .I am a solid individual. . .I am just built to be solid."

Human relations commission attorneys Risselle R. Fleisher and Philip L. Marcus agree. But they are trying to keep the case in the jurisdiction of the commission by contending that obesity in some cases can be a handicap as defined by state law because it is a debilitating condition caused largely by malfunctioning fat storage regulators in the body beyond control of its victims.

In the case of the four women, however, they argue, MTA improperly "perceived" their obesity as a handicap when in fact their condition was not a bar to their ability to work.

MTA attorney Joseph F. Kaufman agrees the women are not handicapped but is seeking to keep obesity off the state list of handicaps so that that the human relations commission will have to drop the case.

He indicated through questioning of obesity expert Theodore B. Van Itallie today that MTA's rationale for excluding overweight applicants from employment is not that fat people make poor bus drivers but that they have a higher incidence of illness and absenteeism than non-obese workers, much of it because of their fatness. "They are very expensive," Kaufman said in an interview.

Van Itallie, who testified for MTA, and another obesity expert, Arthur Frank of Washington, testifying for the human relations commission, both said there are competing theories, but little solid proof, of the exact causes of obesity.

With his testimony repeatedly interrupted by procedural squabbling among the lawyers, Frank supported the idea that obesity is inborn, saying there is evidence of "nonconscious regulatory mechanisms" which, when they break down, cause people to retain more fat.

Van Itallie, on the other hand, testified that obesity is "not necessarily a physiological disorder" and appears to be caused more by cultural influences and social habits and therefore can be controlled by the individual.

The hearing will resume Dec. 28 with the four women scheduled to testify. In addition to Tolson, they are Dorothea Goodman, 33, Carlissa Hawkins, 26, and Betty Wright.