The second adaptation in as many weeks of books that might be said to belong to the genre of chick lit (following “He’s Just Not That Into You”), “Confessions of a Shopaholic,” based on the popular tomes of Sophie Kinsella, is distinctly ill-timed. Not merely because it will be jockeying for the same viewers with a better, if still mediocre, competitor, but because though in the end this garish, frantic, relentlessly cartoonish rom-com pretends to be a warning against mindless materialism, it spends most of the time celebrating it. In the current economic situation it comes across as in extremely bad taste.

Which is a characteristic, to be sure, that also applies to the picture’s airhead heroine Rebecca Bloomwood (Isla Fisher), a giddy young lady who’s deep in debt because she’s a compulsive buyer, racking up loads of credit card debt filling her closets (or, more accurately, those of the pal with whom she lives to save on rent) with designer-designed clothes and accessories she doesn’t need. Pursued by a sleazy bill collector named Derek Smeath (Robert Stanton), she hopes to retrieve things by getting a job at her favorite fashion magazine, the glitzy Alette, named after its super-slick French editor (Kristen Scott Thomas, spouting a French that sounds as though she learned it from Steve Martin during the shooting of “The Pink Panther 2”), and part of a stable run by mogul Edgar West (John Lithgow).

But by accident she instead gets a try-out with a sister publication, Successful Savings, run by handsome, high-minded Brit Luke Brandon (Hugh Dancy), who finds her supposedly homespun take on the financial matters she actually doesn’t understand refreshing. Her column, with the mysterious byline of The Girl in the Green Scarf, becomes a popular sensation—which, given the current realities of publishing, is as implausible as the idea that a giggly clothes horse like Rebecca could string words together in a reasonable facsimile of a coherent paragraph. (Of course, that sort of unlikelihood didn’t stop “Legally Blonde.”)

Where this is going is as preordained as a trust-fund heiress’ drooling over a Prada dress. Rebecca and Luke will get involved despite a lanky rival in the office (sleek Alicia Billington, played by Leslie Bibb). Their incipient romance will be further threatened by Smeath’s intervention, which undermines Luke’s confidence in Becky. Rebecca also has a falling-out with her best friend (and roommate) Suze (Kristen Ritter), who’s miffed when Rebecca’s spendthrift ways lead to the loss of the ugly gown she’s supposed to wear as a bridesmaid in Suze’s wedding—especially since she’s promised Suze she’s attending Shopaholics Anonymous (a colorful group that’s intended to garner lots of laughs, but doesn’t—check out the first Bob Newhart show for pointers on how this sort of thing needs to be done). As if that weren’t enough desperate comedic material, there’s also a prune-faced secretary, a gay receptionist, and—lest we forget—a pair of oh-so-eccentric but oh-so-lovable parents for Rebecca, sweetly supportive but bovine dad Graham (John Goodman) and kooky, thrift-conscious mom Jane (Joan Cusack).

There might have been a time when this drivel might have passed muster among female audiences—it wasn’t long ago, after all, that the “Sex and the City” feature was a smash (and stock portfolios were riding high)—but that time is gone. And “Shopaholic” certainly isn’t saved by Fisher, who made a splash in “Wedding Crashers” but is grating rather than charming here, or Dancy, who comes across like Colin Firth’s pallid younger brother, or by any of the supporting cast (Ritter is particularly annoying, while Goodman, Cusack, Lithgow and Thomas—as well as stalwarts like Julie Hagerty and Lynn Redgrave in smaller roles—are all wasted). Director P.J. Hogan tries to jazz things up with frenetic pacing, but the effort merely encourages Fisher to go even more goofily over-the-top; and glitzing up the package with slick settings courtesy of production designer Kristi Zea, flamboyant costumes from Patricia Field, cinematography by Jo Willems that emphasizes blazing neon colors and visual effects like mannequins coming to life in store windows makes it a visual endurance test, like a Warner Bros. cartoon prolonged to an unendurable two hours. (Editor William Goldberg would have done everyone a favor by trimming some of the excess.)

Of course, excess is what “Confessions of a Shopaholic” is all about, and by the time the picture’s over you feel stuffed and more than a little nauseated by it. During the Great Depression, of course, the suffering masses gorged themselves on films like the Astaire-Rogers musicals as a relief from their miseries. (“Sullivan’s Travels” explained why.) But there’s a cardinal difference between those pictures and this one. They were good.