Can Michelle make it big?

Jaws dropped. Eyebrows arched in disbelief. Shocked tears were doubtless shed in the more emotionally fragile sections of the populace. Sam had been voted off Pop Idol! How could this have happened?

Cute, tousle-headed Sam was the bookies' favourite, the mums' favourite, the grannies' favourite, and - most important - the little girls' favourite. It was simply inconceivable that he should not be swept to triumph. It was as if there had been a star hovering above him, leading the Three Wise Men (oh, and Dr Fox) to lay before him the treasures of the music biz.

Almost before the show's closing theme had died down, the protests began. By Monday morning, the tabloids were full of it. Carol from Catford had had her phone on constant redial to vote for Sam, but after the 50th call, all she could get was the engaged tone. Babs from Basingstoke had called Sam's vote-line at least a dozen times, but had been put through to one of the other contestant's lines. What was going on? Across the country, the cry went up. Fix!

A large part of the outrage that greeted the departure of Sam from Pop Idol was due not so much to any misguided notions of fair play and natural justice - in the music industry? - as to the widespread disbelief that the joke contestant, the show's supposed Aunt Sally, was still in the running. OK, so Michelle could sing at least as well as any of the others - but what did that matter? She was FAT, wasn't she?

Fat is the last taboo in pop. These days, you can throw an air-rage wobbly, threaten your competitors with firearms, indulge massive drink and drug habits, snub poverty-stricken relatives, and still be welcomed into the public bosom. Even allegations of child molestation have not fatally damaged the sales of Michael Jackson or R Kelly - quite the opposite, it seems. You really have to go some, in today's fawning celebocracy, to shock the jaded public into disgust. Something like the rapper Busta Rhymes's recent faux pas at a concert in Copenhagen, where he leapt into the audience to accost a man who had ignored his entreaties for everybody to stand up. "I didn't come from the other end of the world to see people sit on their ass," barked Busta, hoisting the fellow bodily to his feet - whereupon the wheelchair-bound invalid collapsed to the floor. Even then, Busta was able to plead ignorance and apologise, without any great damage being done to his reputation. Because whatever indignity he might have inflicted, and however crass and stupid it may have made him appear, at least Busta wasn't FAT.

Ironically, hip hop is just about the only sector of today's entertainment industry where fat is not necessarily a drawback - except in so far as it makes you a bigger target for the bullets that are an occupational hazard of the genre, as the Notorious BIG discovered to his cost. From Heavy D, The Fat Boys and Boo Yaa Tribe to the latest outsized rap star, Fatman Scoop, fat is an acceptable part of hip-hop culture, perhaps regarded, as in some African and Polynesian societies, as a physical signifier of one's wealth and power, the key elements in today's bling-obsessed black music scene.

In most other music genres, however, fat is the ultimate red-card offence. Folk music's brief time in the spotlight during the mid-Sixties was rudely curtailed when Bob Dylan, the pipe-cleaner-thin talent responsible for the folk boom, contemptuously turned his back on it in 1965. "Folk singing," he sneered, "is just a bunch of fat people." Cue the demise of folk singing.

Indie music is particularly hard on fat performers, unless, like Pere Ubu's David Thomas, the XXXL physique becomes a signifier of the separation from rock music's commercial norms. Thomas's massive figure speaks loudly of Ubu's aggressive contempt for the style-obsessed ways of the music industry, although some would contend that the band's music was indication enough of that. But where less outre music is involved, the indie constituency can be a hard nut to crack. Take the case of Ultrasound, the glam-prog outfit hotly tipped as the next big thing a few years back, whose failure was doubtless hastened by the unashamed portliness of its frontman, Tiny.

Thrash metal has traditionally been a haven for the more well-endowed musician, notably Tad of the grunge-rock band of the same name. But even in that testosterone-rich arena, fat effectively disqualifies one from fame. Compared to the fallen-angel appeal of a Kurt Cobain, Tad had no chance.

The most fat-sympathetic branches of the music industry - apart, of course, from opera, where fat is virtually a prerequisite - are all black. In blues and jazz, big is beautiful; something to shout about rather than be ashamed of. Big Joe Turner, Big Joe Williams, Big Mama Thornton - for these artists, their size was a positive factor, an indication of the massive lung-power at their disposal. In soul music, Luther Vandross has likewise suffered little for his Oprah-esque vacillations in size, while Barry White's vastness was always his unique selling point. The Walrus of Love is unusual, however, in retaining a romantic image throughout his career; for most fat stars, their popularity entails a sort of emasculated, desexualised appeal. They can sing about love, but it's always accepted that they're disinterested observers with no personal vested interest, merely suppliers of the soundtrack to their audience's love-lives. Who, for instance, took Meat Loaf's melodramatic protestations of carnal desire seriously? Like Pavarotti, he always represented an archetype of romantic entanglement, rather than any actual involvement in sex.

The same applies across the gender divide. The soul diva Angie Stone's career has not been as successful as those of less talented but thinner-waisted performers, with whom the audience can better sustain a fulfilling fantasy sexual relationship. Alison Moyet needed a gay male partner to establish her considerable talents in the public's affections, and struggled to keep her audience as a solo performer. And the biggest female star of all, Mama Cass, was only reluctantly admitted into the Mamas and the Papas, despite her obvious vocal talent, because her size was viewed as uncool for the intended audience. In hip times, it doesn't do to be hipper than size 12.

Fat is just about acceptable for established pop performers, on whom it is regarded as a kind of duelling scar, a sign of the life they've led and the problems they're facing. Brian Wilson started out reasonably svelte, until stage fright, drugs and madness took their toll, whereupon he blimped up alarmingly - though most hardcore Beach Boys fans still regard Brian's fat years as the most musically rewarding period of his career. Likewise, David Crosby and The Grateful Dead's Jerry Garcia both expanded under the drug-induced depredations of the rock life, but were pardoned on their previous good behaviour.

The most obviously successful fat pop-star, though, has to be Elvis, whose fans never wavered throughout his most burger-fuelled excesses. Even today, some fans regard Elvis's bloated Las Vegas period as the most artistically rewarding era of his career, claiming that his troubled physique was a reflection of the vicissitudes of his life that made his performances such emotionally compelling experiences. They may be right. But even a star of Elvis's magnitude struggled to overcome the derision that greeted his portly appearance in those later appearances. Whether our Michelle will manage to overcome the pop public's natural distaste for fat with similar aplomb remains to be seen. Even if she wins Pop Idol, her chances of sustaining a career even half as long as those accorded Will and Gareth are surely limited by her inability to conform to the bland stereotype demanded of today's stars, those rake-thin looks only achieved through eating disorders every bit as damaging as an all-pie diet.

We can but hope. But one thing is certain about the current Pop Idol. It ain't over, as the saying goes, until the fat lady sings.