We hold this show-biz truth to be self-evident: Fat is funny -- but not all fatty vehicles are created equal.

	Eddie Murphy plays both the title character and Rasputia in "Norbit." Click photo for larger image. 'Norbit' Starring: Eddie Murphy, Thandie Newton. Director: Brian Robbins Rating: PG-13 for crude and sexual humor, some nudity and language. Web site: www.meetnorbit.com/ Related articles Makeup artist gets in the thick of things for 'Norbit' Will 'Norbit' separate Eddie and Oscar?

The one that lumbers and lugs Eddie Murphy around in "Norbit" is a rent-a-wreck yarn whose nerdy title character (Murphy) was abandoned as a baby at a combination Chinese restaurant/orphanage and raised by its proprietor, Mr. Wong. Upon reaching milquetoast manhood, Norbit is bullied into marrying the huge and hugely mean Rasputia (also played by Murphy) but pines for his childhood sweetheart, Kate (Thandie Newton). He'll be occupied for most of the picture with scheming to escape Rasputia and thwart Kate's impending wedding to Cuba Gooding Jr.

We'll be occupied with Rasputia's monstrous mounds of flesh, repulsively crammed into hot-pink velour sweatsuits and a fuchsia bikini that will require years of therapy to purge from your memory.

If the breathtaking vulgarity of "Norbit's" broad and pervasive fat-joke comedy strikes you as misogynistic, it's because it is. Unlike the females Murphy portrayed in "The Nutty Professor" pix, Rasputia is a vile comic-book villain, ceaselessly terrorizing her pipsqueak husband and everyone else, including kids and dogs. Her raging tantrums are sometimes amusing but far too cartoonish to elicit anything like real sympathy for Norbit or any interest in his love life. Why would the beautiful, oh-so-slender Kate be attracted to such a nebbish? Thandie Newton is given little to work with and is not called upon to give much in return -- just to be a (very vanilla) foil to chocolate Eddie.

The cast is rounded out by Rasputia's cardboard-cohort thugs Terry Crews, Clifton Powell and Lester "Mighty Rasta" Speight, who want to turn the orphanage into a strip club called "Nipplopolis," and by Norbit's ex-pimp pals Eddie Griffin and Katt Williams (their characters are named "Pope Sweet Jesus" and "Lord Have Mercy"), who supply some of the film's few, sporadic funny moments.

Murphy's hemorrhage of bad movies in recent years was just thankfully stanched by his Oscar-nominated turn in "Dreamgirls." Why, barely a few months after regaining respect in such a good film and role, would he throw it away again? Because (1) "Dreamgirls" may have been a lucky casting fluke, (2) "Norbit" was already in production, and (3) male comedians can't seem to resist multiple roles involving female fat suits.

He plays three characters here (I won't reveal the third one, which will surprise and baffle you), and the makeup artists led by Rick Baker have done an admittedly terrific job. There's fun in Murphy's morphing -- but Murphy is having most of it.

As if the "Nutty Professor" and Martin Lawrence's "Big Momma" pix weren't enough, grotesque obesity in drag has become a kind of genre in itself, not unlike black-face minstrel shows of yore -- something for current and future cultural anthropologists to puzzle over. And what better time than in Black History Month?

Study questions for Murphy and director Brian Robbins: What's the difference between fat black ladies bashing skinny husbands in "Norbit" (2007) and Sapphire henpecking Kingfish in "Amos & Andy" (1947)? Between black-pimp stereotypes now and Stepin Fetchit caricatures then? Why is it legitimate farce or satire when blacks do it but racist when whites do?

Black-shtick slapstick is a phenomenon unto itself. At the preview screening of "Norbit," people were laughing their real or padded rear ends off. But I continue to hold out hope that Eddie Murphy will one day make a real comedy for the ages.

This one is strictly for the ages of 12 to 14.