This fat has been chewed before

Physical transformation or not, “Norbit” is unlikely to send Eddie Murphy back to the Kodak Theatre in a year’s time. But why grouse when the movie qualifies him for even greater honors? Surely some humanitarian organization will recognize the selflessness with which Murphy has taken three of the movie’s major roles, thus saving two other actors from a nasty black mark on their resumes.

Had Murphy not snapped up the role of Rasputia, the bulging bete noire of the movie’s emasculated hero, the job of serving as the butt of the movie’s endless string of fat jokes would have fallen to an honest-to-goodness actress, who might not have borne the serial humiliation with anything like Murphy’s grace.

Of course, an honest-to-goodness actress might also have brought some humanity to the role, which would have squarely derailed the movie’s plan of attack. Murphy’s mild, bespectacled nerd may get top billing, but Norbit is essentially a monster movie, with Rasputia’s designs on Norbit closely resembling Godzilla’s plans for Tokyo.

Although she is first seen shielding the orphan Norbit from a pair of sandbox bullies (Murphy graciously cedes both roles to 9-year-olds), Rasputia is quickly transformed into a short-tempered leviathan. After a brief montage of bone-crushing nuptial bliss, Norbit emerges as a henpecked husband choking on his substantial ball and chain, a pantywaist literally smothered by his wife’s clutching affections.

Hope arrives in the impossibly thin form of Norbit’s childhood love Kate (Thandie Newton), but obstacles stand in their way -- for starters, Rasputia’s mountainous, muscle-bound brothers and Kate’s secretly on-the-make fiance (Cuba Gooding Jr.). There’s also business involving the fate of the orphanage where both Norbit and Kate were raised, currently run by the foul-mouthed, obstreperous Mr. Wong (Murphy, yet again). But in essence, Norbit’s quandary boils down to a choice between the fat girl and the skinny girl. The Lady, or the Whale? (Should the latter seem like an unkind epithet, let us point out that Mr. Wong’s otherwise unmotivated interest in harpooning does not go to waste.)

There is, of course, no question which Norbit should choose, although the fact that Kate looks as though she might explode if placed in close proximity to food might give a wiser man pause. Rasputia is a thoroughly repellent creation, as reductive in conception as she is expansive in girth. To be fair, she is only one among the movie’s gallery of lazy stereotypes, which include a pair of jive-talking pimps (Eddie Griffin and Katt Williams), a flamboyant aerobics instructor (Marlon Wayans) and an Italian restaurant owner (Anthony Russell) with Old World speech patterns and a dining room filled with red-checked tablecloths.

Murphy and his brother Charlie, who collaborated on the screenplay, seem to have drawn the wrong lesson from the latter’s stint on “Chappelle’s Show.” Where Dave Chappelle used stereotypes to confront prejudice, the Murphys (and their co-screenwriters Jay Scherick and David Ronn) merely squeeze a few grudging drops from caricatures that were wrung dry in the age of vaudeville.

In “Dreamgirls,” Murphy gave a performance of uncommon discipline, channeling his talent for mimicry into the character of a protean soul singer who barely exists when he’s not on stage. “Norbit’s” director, Brian Robbins, has no interest in shaping Murphy’s schtick. His idea of direction is to plant the camera and let Murphy do his thing. Digital technology has eliminated the doorframes and lampposts that were once a staple of dual-role performances, but no one has invented a way to curb the ego of a screen-hogging actor whose idea of shaping a scene is to start loud and get louder.

The one member of Norbit’s team who can hold his head high is makeup artist Rick Baker, who oversees Murphy’s mightily impressive physical transformations. Were it not for the distinctive indulgence the camera lavishes on him no matter what part he’s playing, Murphy would be virtually unrecognizable under his layers of latex. But changing the package doesn’t change the product, nor the fact that it’s well past its sell-by date.

“Norbit.” MPAA rating: PG-13 for crude and sexual humor, some nudity and language. Running time: 1 hour 42 minutes. In general release.