They said they were supposed to be part of a wholesome all-American movie about diverse life styles. Instead, the three Maryland members of the National Association to Aid Fat Americans Inc. wound up in a sexual satire video.

The three agreed to be filmed for a movie while attending a convention of the organization in Crystal City eight years ago. But recently friends informed them that shots of them appeared -- accompanied by pig and cow noises -- in a spoof of a prime-time newscast in the video "The Sex O'Clock News," according to a $2.1 million lawsuit filed last week in Howard County Circuit Court.

"I would never have approved of being in something like that," said Paula Dachis, an accounts manager with an investment management firm in Rockville. "It goes against everything I've worked for for nine years," the Columbia resident said in an interview.

Dachis, a past president of the 1,500-member group, along with Russell F. Williams of Hagerstown and Margaret Fox of Waldorf, filed the lawsuit for the damages and a preliminary injunction to ban the rental and sale of the video in Maryland.

The plaintiffs say they were displayed in an "outrageously derogatory and humiliating manner" in a segment titled Club Fed in the 90-minute video. The lawsuit said the film discriminates against fat people and ridicules their life style and personal views.

According to the suit, the video, which includes photographs of the plaintiffs dubbed over a soundtrack of barnyard noises, suggest the NAAFA members are "piggish and cowlike in their appearance, mannerisms and behavior."

The plaintiffs said they are further humiliated in the film during a scene in which a television anchor person says they attend Club Fed "solely for the purpose of eating, sleeping it off and eating some more . . . . "

Because of the film's negative portrayal of fat people, Dachis said she fears neighbors, coworkers and friends are laughing behind her back.

"I never know when I'm standing in the grocery store and someone is looking at me, if they have seen the movie the night before," said Dachis.

The suit names as defendants the film's producer, Romano Vanderbes, president of Chase Films Inc., in New York City; Prism Entertainment Corp., a Los Angeles-based home videocassette movie distributor, and William Milling, an independent producer who shot the raw footage of the plaintiffs.

Earl Rosenstein, senior vice president of Prism Entertainment, said his company obtained distribution rights to the movie about one year ago from Vanderbes.

Rosenstein said the R-rated film has been a "pretty good seller" for Prism, which distributes home videos to 30,000 retailers in the United States and 4,000 outlets in Canada.

But Rosenstein said he's confident Vanderbes obtained proper releases from partipicants in the movie. "I'm sure he has that," Rosenstein said. "When we get a home video, we ask for proof of chain of title. Vanderbes supplied that."

But Dachis said she and the other plaintiffs "never consented to be in 'The Sex O'Clock News.' It's embarrassing to be associated with it."

She said the three problems began in 1979 during the Labor Day weekend convention of the fat Americans' association, which calls itself a lobbying and civil rights group for overweight people.

Milling, an independent producer, approached the plaintiffs, as well as other conventioneers, about appearing in a film he was working on called "The American Dreamer," the lawsuit said.

According to Dachis, Milling told the plaintiffs his movie about diverse life style in America would provide a sensitive portrayal of fat people. Milling filmed the plaintiffs at dances, workshops and other outings at the convention, said Neil Dachis, the plaintiffs' attorney and Paula Dachis' husband.

However, Milling later sold the raw film footage of the convention to Vanderbes, who used the material for The Club Fed segment of his home video movie, "The Sex O'Clock News," the lawsuit said.

In December 1986, the plaintiffs found out about the movie when an acquaintance rented the video movie and recognized one of them, said attorney Dachis.

Neither Vanderbes nor Milling returned phone calls made yesterday to their New York offices.

According to the lawsuit, "The Sex O'Clock News" is "very popular" and "frequently rented out at local video stores."

A spokesman for Erol's, which has 90 video stores in the Baltimore-Washington area, said "The Sex O'Clock News" is available only as a special order purchase for $79.95.

However, no one has ordered the video in the last year, said Vans Stevenson, the video chain's director of public relations.

Paula Dachis said publicity about the lawsuit probably will boost rentals and sales of the videos. But she said fat people have rights too.

"It's cheap trash," she said. "I can't see where it has any socially redeeming value."