Some cable companies are offering Showtime's 10 p.m. debut of "Fat Actress" free to subscribers tonight, but not Comcast. The show isn't much of a deal either way.

It's too bad, really. The half-hour sitcom is built on a promising real-life premise. Over the past several years, former "Cheers" and "Veronica's Closet" star Kirstie Alley put on so many pounds, she became a sustained National Enquirer scandal. Then she pulled herself together — mentally.

"It was sort of like I can either die, slit my throat or I cannot work for a year or whatever," she told critics. "Or I could make it. I got real 'Matrix,' went with the flow and thought, 'I can turn this into something fabulous.' "

To this end, Alley recruited as partner and co-producer Brenda Hampton, creator of The WB's long-running "7th Heaven" and a former comedy writer.

The result is an unscripted and underdeveloped concept featuring Alley's weight issues in a town where looks are everything. Famous pals such as John Travolta mix with actors portraying Alley's agent and personal assistants, a hybrid approach that inevitably recalls HBO's "Curb Your Enthusiasm."

But the differences are vast. While I'm no fan of Larry David's relentless misanthropy, "Curb Your Enthusiasm" is superbly written and constructed with an eye to the audience.

RANDY TEPPER / SHOWTIME Rachael Harris and Bryan Callen play Kevyn and Eddie, two of Kirstie Alley's fawning assistants on "Fat Actress." The Showtime series uses a hybrid formula of Alley's famous pals portraying themselves and actors.

The mostly improvised "Fat Actress" conveys the sloppy effect of friends amusing each other with well-worn anecdotes while outsiders wanly try to smile. It's a celebrity vehicle, an approach that shows up in the lack of effort and condescension.

"Fat Actress" longs to send an empowering message. And early in this evening's episode, Alley launches a short, well-taken diatribe about all the TV roles for fat men.

Yet the overall show treats viewers as if they were tabloid ghouls eager mainly for the crude details of Alley's weight struggle and longing to see whom she hangs out with.

Surely "Fat Actress" could have fetched up a few universal experiences about how it feels for a woman to go from beautiful to repulsive in the pitying judgment of others.

The format is unsatisfying in other ways. During an interview, Alley made the astute observation that "great comedy is great, overly dramatized tragedy."

While there's plenty of over-dramatization, "Fat Actress" doesn't deliver emotional revelation. Like the equally antic Jim Carrey, Alley is somehow damaged without being vulnerable. When she weighs herself in tonight's opening scene and crawls across the floor loudly bawling, it's strictly a cartoon.

This inaccessibility draws another distinction between "Curb Your Enthusiasm" and "Fat Actress." Call it the schadenfreude factor.

In "Curb Your Enthusiasm," David pays the price for arrogance and self-delusion in the only form that counts — face-to-face humiliation by one's peers, meaning most of the L.A. establishment.

In "Fat Actress," Alley remains safely insulated. NBC chief Jeff Zucker, who appears briefly, is appalled at her size but waits for her to leave before he expresses it. John Travolta checks his annoyance with her histrionics until she's out of earshot.

This may be true to real life. Yet it means the sharpest humor in "Fat Actress" often occurs after the star is gone.

The embarrassment Alley does experience in person comes from parking valets or washroom attendants, whose insolence she easily brushes off. Compare that to "Curb Your Enthusiasm," where a helpless David is put at the mercy of mistreated minions.

Curiously, the people who live with Alley on a daily basis as her personal assistant, stylist and agent have less privilege to speak their minds than one might imagine. In the roles of Kevyn (Rachael Harris), Eddie (Bryan Callen) and Sam Raskal (Michael McDonald), the emphasis is on fawning and humoring.

Again, it could be real — and doesn't matter. "Fat Actress" inadvertently demonstrates the benefit of hiring great writers to make up stuff. Concerning Alley's abilities, a conventional sitcom, like the ones that made her famous, would be more suitable.

Alley certainly has gotten publicity mileage from her new persona. In a twist that the seven-episode series foreshadows, she's now a Jenny Craig spokesperson and expects to lose her excess avoirdupois as the weeks roll by.

That's just about enough time for "Fat Actress" and the fat actress to kiss each other good-bye.

TV note: Showtime precedes "Fat Actress" with the 8:15 p.m. debut of "Super Size Me," the Oscar-nominated documentary that follows filmmaker Morgan Spurlock as he chows at McDonald's for 30 straight days. After "Fat Actress," it's an edition of Penn and Teller devoted to fad diets. Binge and purge: That's TV.

Kay McFadden:

kmcfradden@seattletimes.com