But think twice before you order Spears to remedial gym training. According to the Daily News, Madonna’s “stringy,” “veiny” arms are “more like a horror show than something out of a gym.” “Time to quit the gym, Madge!” says writer Nicole Carter — you are working out too much! Fellow Daily News writer wonders, “Are Kate Gosselin and Madonna workout buddies?” Because guess what? Kate’s too-sculpted biceps, while not yet veiny, are on a slippery slope to mimicking the Material Girl — “time to soften the image and drop the dumb bell now!” (Clearly, neither one learned their lesson from the first lady). Perhaps both are just trying to stave off the dread “bingo wings,” also known as “dinner lady arms” that, according to the Daily Mail, are nearly impossible to remedy without hideously painful surgery — “for most women of a certain age there’s little to do except slip on a cardigan.”

Now I’m really confused. Do I make that afternoon yoga class, break out the barbells, or just sit in the yard and eat lettuce and drink cucumber water? Do they make cardigans I can wear in July?

OK, so tabloid writers are fucking batty. We all knew that, right? We can — and should — rage about body image all we like, but it may also be perfectly reasonable for the rest of us to conclude that if one wishes to avoid national exposure each time we gain or lose a few pounds, perhaps we should choose a career in which one does not quite literally make money off one’s looks. Truth: Madonna’s arms, unlike Michelle Obama’s, do not look like the kind of thing one gets simply doing some morning bicep curls. They look more like the result of a 50-year-old woman in full-blown panic mode that she might finally be succumbing to the natural results of her age. And that does make me feel sort of sad and weird.

But what gets me is not merely the fat-shaming of women who, by no rational measure, should be considered “fat.” It’s also the inevitable miracle weight-loss success story, which every last Hollywood publicist insists their client achieved through old-fashioned diet and exercise — even if we all know that no one has ever lost 10 or 15 pounds in less than a month without severely unhealthy calorie restriction, no matter how many wind sprints their personal trainer may put them through. And let’s be honest: What we are calling the difference between “fat” and “thin” here is the difference between about 10 or 15 pounds; a concave stomach versus a bit of a muffin top when one is wearing the skinny jeans one bought 5 pounds earlier.

To get all academic about it, this tells us nothing about health: Even by the notoriously useless and often unfair standards of the BMI table the average woman can fall within about a 25-pound range, without ever veering into being officially “under-” or “over”-weight. By some estimates (calculated by the likes of Star magazine, so I’m not vouching for accuracy here): I’ve seen “fat” Britney listed at 125 pounds (which, at 5-foot-5 would give her a a low BMI of about 20) up to about 140 pounds, which would give her a BMI of 23, still 10 pounds shy of “overweight”; “thin” Britney was about 105 to 110 pounds for a BMI of 17 or 18, about 5 to 10 pounds “underweight”; “fat” Jessica Simpson was about 140 pounds, which, at 5-foot-3, would give her a BMI of 24 — still within the border of a “healthy” weight. (If she’s 5-foot-2, as other publications report, well, she would have been 5 pounds “overweight.”)

Having not personally weighed and measured these ladies myself, I can’t tell you if these weights are accurate, or merely the inventions of some tabloid editors or publicists. But they are, at the very least, the figures available to women and girls who wish to measure their own bodies against those of the stars. And what they do tell us is that, if anything, these women are likely closer to being a “healthy” weight when they are being maligned as “fat.” Yet when Britney or Jessica starts to show a bit more flesh in their midriff-baring stage costumes or high-waisted jeans, everyone starts to joke about their alleged indulgence in barbecue, fried chicken and good old Southern food; when they get “back into shape” it’s all about their fantastic workouts with their personal trainer and eating fresh veggies. (Never mind that it could just as easily be the Beyoncé Knowles “subsisting on lemon juice, water, cayenne pepper and laxatives for two weeks” diet plan; the Angelina Jolie “my mother died and that stressed me out” diet plan; or the time-honored cigarettes, coffee and cocaine diet plan. Or maybe just bulimorexia.) Unless, of course, they work out too much. Because everyone knows veiny biceps on a lady are, like, way unfeminine.

And so we have arrived at Zac Efron’s moment. In this month’s Interview magazine, the well-scrubbed 21-year-old star of “High School Musical” loosens the shackles of his pukka-shell necklace and undergoes a dirty-sexy makeover — black-and-white photos feature him rolling in the mud with a naked model (Lithuanian Edita Vilkeviciute), her pert nipples visible, and looking like he is 15 years late to Chris Isaak’s “Wicked Game” video shoot. The whole package is a self-conscious attempt to rescue Efron from the sea of Disney banality in which he has been dog-paddling for some time: The artsy cover ominously declares, “Zac Efron Is the Future.” The interview is conducted by beloved indie director Gus Van Sant — a man whose stamp of approval is so coveted by young Hollywood that it became a plotline in HBO’s “Entourage” — and the pair gab about vintage furniture and Efron’s upcoming period film with Richard Linklater, “Me and Orson Welles.” The repeated message here is that you won’t have Zac Efron to sing your four-part harmonies anymore. On Tuesday came the announcement that Efron had pulled out of his starring role in the remake of “Footloose,” a part that seemed to seal his fate as a song-and-dance plaything for tween America and the next logical step in his retread of vapid ’80s teen idoldom. Ditching that part is possibly the most interesting thing Efron has done in his career — which is, admittedly, a short list, including the time he told Elle magazine that his mom bought him an economy box of condoms. 

Even in the pantheon of bland teen stars, Efron always seemed particularly animatronic. (That’s not even his real voice in the original “High School Musical,” though he insisted on singing in the sequels.) With his ’50s-era Boy Scout good looks, annoyingly windswept bangs, and the made-for-the-tabloids romance with Vanessa Hudgens, Efron has never been much more than a punching bag for those of us over 10 years old. When Rolling Stone declared him the “New American Heartthrob” in 2007, it seemed to be saying more about its own desperate bid for relevance than anything else. “As long as I stay boring, I think I’ll be fine,” Efron said in the cover story. And there did not seem to be any danger of him doing otherwise. Which is another reason why this moment is exciting: He could have sucked on the bong of “HSM” for years, living a cozy existence fortified by Teen Choice awards, in which the most serious question he faced was whether or not he liked to wear makeup. 

I don’t mean to suggest that by splattering mud on his face and pressing his pecs against a naked lady, Efron will suddenly morph into Johnny Depp. Depp displayed hints of his talent even in his earliest roles, whereas Efron’s chops have yet to manifest. In fact, it’s a bit squirm-inducing to hear about Efron’s artistic aspirations, however fledgling and undefined they are. “I’m getting a list of great films on my iPhone,” he told Gus Van Sant, “and every time somebody mentions one, I try to go out and watch it.” (He just saw “Ordinary People.” Verdict? “I was amazed.”) His next film is “17 Again,” a hokey-sounding age-inversion film in which he plays a 37-year-old stuck in the body of a teenager, which is not likely to land him on anyone’s Oscar shortlist.

Nevertheless, there’s something invigorating about a teen idol attempting to wriggle free of his constraints. It’s a gamble for a star whose fame relies on the conflicted desires of the young girls (and boys) who adore him, in part, for his androgyny, because he is unthreatening, sweet and cuddly as a puppy. No matter how sexualized our culture becomes, the overwhelming success of “High School Musical” — in fact, of every teen idol — confirms that kids crave the soft-focus fantasy of romance and sexuality while keeping all the dirty, nasty stuff at arm’s length. (Hello, Jonas Brothers.) Trying to transition into a more grown-up role is the sword on which so many beloved teen idols have fallen. But whether he can pull a Depp or a Timberlake, or whether he winds up as the next David Cassidy, forever plagued by the credibility that eluded him, Efron’s career now has a quality it has lacked for so long: It has become unpredictable.

 Teen idols who have crossed over

The career span of a dreamy pinup is often painfully short, but a handful have cheated fate and turned themselves from punch line to marquee player.  Here are a few hits (and near-misses):

Johnny Depp

Almost as soon as Depp pierced public consciousness as the young star of late ’80s teen-cop drama “21 Jump Street,” he made it clear he wasn’t a going to be a garden-variety idol. He started talking in interviews about making a movie of Kerouac’s “On the Road” and threatening to shave off his hair. By 1990 he was fleeing his prime-time trap for a starring role in John Waters’ “Crybaby,” which he described at the time as “the ultimate juvenile-delinquent musical comedy” — soon to be followed by Tim Burton’s “Edward Scissorhands,” the first of many quirky movies he would choose on his way to becoming one of the world’s most admired actors.

Justin Timberlake

From his early appearance on “Star Search” to his squeaky-clean image in ‘N Sync, there was little to suggest towheaded Timberlake was anything more than harmless fantasy fodder. He and Britney were the reigning fairy tale couple — but in 2003, they broke up and in one fell swoop, both young lovers tumbled into adulthood. Timberlake took up with the very grown-up Cameron Diaz, and his debut album catapulted him to superstardom. He became a regular Rolling Stone cover boy, made even more infamous for exposing Janet Jackson’s nipple during the Super Bowl.  But he found respect and widespread critical acclaim with his adventurous album “FutureSex/LoveSound.” Timberlake had pulled off the ultimate former teen-pinup feat: building up artistic credibility while keeping the fans panting.

Britney Spears

The beleagured pop star has zigzagged across the line of credibility so many times that it’s hard to remember when she first arrived. La Spears was incubated in “The New Mickey Mouse Club,” of course, and burst on to the pop scene with an album that had one bona fide megahit (“Baby One More Time”) and a lot of cloying nonsense. She had all the trappings of a one-hit wonder, but Spears leveraged her time in the spotlight with a series of then-shocking magazine spreads, beginning with David LaChapelle’s Rolling Stone cover in 1999, flaunting her sizzling teen bod while promising to keep her virginity tucked away in a heart-shaped box. It was all a bunch of calculated nonsense, of course, but it worked, along with all those perfect Max Martin pop confections, so that by the time she swapped saliva with Madonna on the MTV Video Music Awards in 2003, the homespun Louisiana teenybopper had transformed herself into the country’s reigning pop princess. And then, other things happened. Maybe you heard.

Bobby Brown

Booted out of the ’80s teen group New Edition for bad behavior, Bobby Brown could have easily been a footnote to the ’80s boy band era — and a minor one at that. His first solo attempt was largely ignored, but his 1988 smash album “Don’t Be Cruel” was all swagger and sass, and the hit “My Prerogative” became an anthem for teen-idol rebellion when Britney Spears remade it in 2004. Brown became a blueprint for Spears in another way, as his music career soon became eclipsed by the hot mess of his tumultuous reality-show life.

Mark Wahlberg

A life of crime or life in a boy band seemed to be the two options facing Mark Wahlberg at the age of 13. He switched off between the two, spending a short stint in his brother Donnie’s band New Kids on the Block and another in jail before finding fame as Marky Mark and the Funky Bunch. The party jam “Good Vibrations” was a massive hit, as was the video in which Wahlberg flexed his bare, extremely buff chest. His career as a Calvin Klein underwear model eventually overshadowed his music, and a dead-end future as a hunky has-been was looming. But in 1993, Wahlberg got a part in a movie, which led to a string of strong performances in movies like “The Basketball Diaries” and “Boogie Nights.” Nowadays, Wahlberg not only acts (nabbing an Oscar nomination for “The Departed” in 2006) but he’s also a Hollywood exec, producing the HBO series “Entourage” (loosely based on his own experiences) and “In Treatment” — about as impressive an outcome as a pretty boy teen idol could imagine.

Miley Cyrus

Last April, tween superstar Miley Cyrus, aka Hannah Montana, tried her hand at a different kind of girl power: posing for a racy Annie Leibovitz portrait (just as David Cassidy had once done), draped in nothing but a bedsheet for the cover of Vanity Fair. What was presumably meant to signal a break from the goofy girldom of her Disney career prompted a ferocious backlash among parents and Disney itself, panicked that it might be losing its prized pony. A contagion of apologies and hand-wringing trend pieces later, the moment still stands as a transition for Cyrus, who managed to catapult herself into the national conversation, though she’s back in line now for the most part, starring in April in another soft-focus “Hannah Montana” film. More moments of teen rebellion inevitably await.

 David Cassidy

OK, so David Cassidy never exactly crossed over to mainstream credibility. But it’s not like he didn’t try. Before he was cast as Keith Partridge in 1970, Cassidy had dreams of being a serious actor and musician — but his massive TV superstardom derailed his plans and left him with a trail of screaming girls and a zillion lunchboxes bearing his image. ”I was playing a part on television, and that became the David Cassidy story. But underneath, there was this guy who was dying to do ‘Purple Haze,”’ he once told Entertainment Weekly. He desperately tried to shred his image by posing for a nude Annie Leibovitz Rolling Stone cover, his pubic hair on show, and dissing “The Partridge Family,” but to no avail. Cassidy didn’t find a place for himself until 1983, when he took the lead role on Broadway in “Joseph and the Amazing Technicolor Dreamcoat,” a musical that has become a refuge for many former teen idols (Donny Osmond, Andy Gibb, Michael Damian and Leif Garrett among them) seeking salvation.

– Joy Press and Sarah Hepola 

For the rest of us? Not so much. The year kicked off on January 22 with the shocking accidental death of Heath Ledger. The story had all the familiar and sordid mixings of juicy tabloid tragedy: Drugs! Depression! A heartbroken (and famous) ex-wife! An Olsen twin! And yet, Ledger’s death wasn’t fun, wasn’t funny, wasn’t the kind of downward spiral whose images you pass around like Christmas snapshots — images like, say, a bald Britney Spears banging on an SUV with an umbrella or Lindsay Lohan passed out in a car. No, the demise of Heath Ledger was dark, baffling, sad. For years, as celebrity shenanigans grew increasingly more ridiculous, more desperate and anguished, it seemed inevitable that some public tragedy would cast a pall over the bitchy fun of celebrity gossip. Who knew it would involve a spotlight-shunning actor who had only just completed his most stunning performance yet?

The celebrity industrial complex was already maxing out in 2007, when Heather Havrilesky wrote, “What’s fascinating and disturbing about this moment in our culture is this pervasive feeling of vertigo, the push and pull of new media marginalizing the more historically weighty stories while the flashiest trivia holds the camera’s gaze.” It seemed that nothing mattered as much as David Hasselhoff drunkenly snarfing a burger or Alec Baldwin screaming at his poor daughter, and it looked like that trend might continue until, as Mike Judge had joked in his 2006 satire “Idiocracy,” the country was run by a camera-hogging professional wrestler. Celebrity minutiae and misdeeds became a kind of media wallpaper overshadowing real stories like the war in Iraq and concern about the economy. (The economy? Who cared about the economy?)

But then, the culture shifted. Politics seemed, weirdly, like something we could believe in again. Empty gossip felt, well, emptier. As Rebecca Traister wrote back in March, in a terrific and prescient piece about the demise of celebrity gossip, “The pleasure we take in snurfling through the trash bins of those more rich and famous than we seems to be waning, leaving me a little sad,” Traister wrote, “but perhaps, at the end of the day, just a little less dumb.”

As the most stirring election in recent memory revved up, the daily banalities of A-list celebs like Tom Cruise, Jennifer Aniston, George Clooney and Brad Pitt took a back seat to rumor-mongering about Sarah Palin and a discussion of whether or not Barack Obama wore boxers or briefs. In May, Us Weekly editor Janice Min told the New York Times, “When you look at the great celebrity dramas of the last few years, you have Team Aniston, Team Jolie, Team Heidi and Team Lauren. And now we have Team Hillary and Team Barack.”

But it wasn’t merely the high voltage of the political season that tanked celebrity gossip. The industry itself had badly overreached — like Wall Street, the real estate market, Starbucks and every other American enterprise bent on total domination. Supermarket stands had become a hot mess of tawdry tabloids. (Who were the people so unsatisfied with Star, People and Us Weekly that they required Celebrity Living, too? Well, whoever they were, there weren’t enough of them. The magazine folded earlier this year.) 

By late December, even celeb site Jossip raised the white flag in a post called, “Gossip’s Dead and It’s Everyone’s Fault.” The item offered a brief summation of the fallen soldiers on the field: “Ben Widdicombe was the first to go, ankling his post as the New York Daily News’ most respected gossip columnist. Next were Rush & Molloy, the married gossips who since 1995 had also penned a column for the Daily News — they wanted to focus on other stories for the paper. Then Jo Piazza, whose scuttlebutt replaced Widdicombe’s, quit, too. Jossip’s gossip-oriented sister site Mollygood shut down, much like the short-lived PageSix.com before it. Also, tabloid sales continued to shrink.” Layoffs hit Gawker and its sister site Jezebel. TMZ, which had so zealously launched its own TV show in 2007, ended the year with a decrease in readership — a rare occurrence online, where new users appear by the minute. It seemed deeply symbolic when Mr. Blackwell — the bitchy tabloid queen responsible for “The Worst Dressed List,” a Schadenfreude tradition that gave birth to a gazillion “fashion police” — passed away in October. It was fitting, almost. The end of an era. Or, depending on your perspective — an error.

It was 20 years ago that Brat Pack pretty boy Rob Lowe scandalized the country by making a sex tape with two women he’d picked up in a bar, one of whom turned out to be (gasp!) 16 years old. The event was, in many ways, the beginning of the modern tabloid age and a glimpse at the two decades to come, in which celebrity scandal captivated the public imagination, whether it was pop royalty dethroned (Michael Jackson, Britney Spears) or beloved role models besmirched (OJ Simpson, Woody Allen and, of course, Michael Jackson) or pretty-boys-turned-prison-mates  (Robert Downey Jr., Tupac, Kiefer Sutherland) or the parade of attention-starved exhibitionists who seized the spotlight in the first part of this decade, the LiLos and the Brit-Brits and the MTV reality queens. It is almost quaint to think of Lowe’s sex tape now: A romp with two chicks, one of whom lied about her age. People were outraged! Fast forward 15 years or so, and R. Kelly is pissing on 14-year-old girls and still making hotly anticipated albums.

But the sheer volume of celebrity scandal has ground us down, made us cynical and mean-spirited. It’s damned hard to care anymore, to respond to souls in crisis with little more than a sneer of contempt and one giant eye roll. Just consider the case of Amy Winehouse, the English crooner and tabloid favorite who has been in a spiritual and chemical freefall since she first hit the charts in 2006. Things looked bright when she finally fled to rehab in January 2008 — after a series of epic, bloody blowouts — but by June she was flailing again, with cuts on her arms and troubling reports of early-stage emphysema. By December 2008, she was back in rehab once more. And all of it was so grim, so ugly and hopeless — an implosion via RSS feed — that you would be forgiven for failing to care. After all, was it really such sport to laugh at a woman with a black eye and a fat lip, a woman lurching through a darkened street with broken heels and a glazed, pained look in her eyes? Was it really still funny? Had it ever been?

Of course, there were a few celebrity scandals of the old-fashioned variety in 2008. Lindsay Lohan began dating a woman, Samantha Ronson (and appeared — finally, if only temporarily — calmed by it); Britney Spears made yet another comeback and was dogged by yet another series of reports about her dangerous weight loss and failures at mommyhood; Gwyneth Paltrow and Coldplay’s Chris Martin were reportedly on the outs; Hulk Hogan split with his wife Linda, who  began dating a 19-year-old. Then there were the happy endings and silver linings: the surprise weddings (Mariah Carey and Nick Cannon), the shotgun weddings (Ashlee Simpson and Pete Wentz), the high-pressure engagements (Jamie-Lynn Spears and whoever is engaged to Jamie-Lynn Spears), the about-time weddings (Jay-Z and Beyonce Knowles) and the straight-up tear-jerkers (Ellen Degeneres and Portia de Rossi). Oh, and I almost forgot: Clay Aiken’s gay. Does that count as celebrity scandal? Hmm. I didn’t think so.

Oddly, the year’s most interesting celebrity gossip came from a thoroughly unlikely source: Tina Fey. Bolstered in no small part by her eerie resemblance to a certain vice-presidential nominee (and her classic “Saturday Night Live” performances), Fey found herself in the national spotlight and landed a $6 million book deal at a time when the bottom was practically falling out of the publishing world. Her NBC comedy “30 Rock” — once dismissed as a doomed critical darling — boasted cameos from no less than Oprah Winfrey, Jennifer Aniston and Steve Martin. Fey graced the cover of Vanity Fair twice in one year, with a profile that painted her as the ultimate anti-celebrity: a teetotaler, a tireless worker, a boring homebody happily married to a nice guy. And the story of how she got that mysterious scar on her chin — she was cut in her front yard at the age of 5 — made national news. (Our Tina Fey? Yes, our Tina Fey!) As Britney Spears continued to disappoint, as critics threw tomatoes at Tom Cruise in their early reviews of “Valkyrie,” Fey emerged as the scrappy hero of recession-era America: a self-made woman with real brains — and real boobs!

They say that celebrity is a reflection of how a culture would like to see itself. And though I shudder to think what the long and shameful reign of Paris Hilton says about our country, what I do know is that I’m glad Tina Fey has the crown these days. It was about damn time for a regime change.