It all started with the muffin top, that telltale spillage of flesh over the top of a tight waistband. Then came the bingo wing, the supposedly shaming droop of flesh beneath middle-aged arms; or maybe it was the cankle (chubby ankle), or the saggy knee. I forget now.

A muffin top? Yummy. No, such names for women's body parts are unsavoury Read more

It’s hard for women to keep track of which specific body part is currently being shamed to death, when it seems to be open season on all of them. But even by the demented standards of female self-flagellation, the emergence of “arm vagina” – aka the slight fold of flesh created where the average arm meets the average body – is a low point.

If you’re reading this in a public place and unable immediately to check whether you have arm vagina, then let me help; you almost certainly do. Everyone does. It’s basically a normal human armpit, which tends to involve some spare capacity in the flesh department, what with it being difficult to raise your arm otherwise.

But in Hollywood, having a freakishly fat-free underarm, as taut and smooth as a plastic Barbie doll’s, is apparently the new goal. In a long list of mad things female actors are conditioned to worry about exposing on the red carpet, arm vagina is “the one that comes up all the time”, as the celebrity stylist Rebecca Corbin-Murray told the Times this week.

Merely having abs that could crack walnuts and a face betraying no sign of human ageing isn’t good enough any more – presumably on the grounds that nothing is ever good enough for women making a living in the public eye, and consequently for self-conscious teenagers striving to copy them.

Spend hours in the gym diligently removing all possible vestiges of flesh beneath your arms and the snipers would only move on to something else, although God knows there isn’t much left to pick on. Eyebrow pudge? Overweight elbows? Do the back of my knees look big in this?

In fairness to Corbin-Murray, she wasn’t arguing that ordinary women should panic about the beauteousness or otherwise of their armpits, or that doing so was in any sense rational. She was merely pointing out, as a person who gets paid to protect women from public shaming on the red carpet, how freakishly difficult that has become.

But she was doing so as part of one of those fluffy “what not to wear this Christmas” spreads aimed at perfectly normal, intelligent women who read stuff like this at the end of a long day because fashion’s meant to be fun, a cheery distraction from worrying about Donald Trump accidentally starting a nuclear war. And the trouble is, this isn’t fun. It’s cruel, and it goes way beyond projecting an ideal of female beauty in the way the movie industry always will.

Men in real life don’t go around sexually rejecting women solely on the grounds that their armpits could have been a bit more toned. No sane person ever chose a film to watch on this basis. All moral qualms aside, there’s not even an obvious commercial imperative to making actors feel quite this paranoid. So why do the fashion, film and media industries still contrive to make women feel there’s something gross and hateful about their very flesh, the space they occupy in the world?

The way Hollywood exercises power over women has been a hot topic since the first allegations against Harvey Weinstein emerged, and yet we have in some ways been slow to join the dots between individuals’ behaviour and the culture in which this power came to seem almost normal. It’s striking how many of Weinstein’s victims say that before he lunged, he would tell an actor or model that she could do with losing a few pounds.

The inference was that she was lucky even to be invited to his hotel room, given how embarrassingly short of the ideal she fell. There is more than an echo here of the way abusive men chip away systematically at a partner’s confidence until she feels worthless, undeserving of better treatment.

But in treating women like lumps of meat, Weinstein was in a way simply doing what his industry has been doing to them for years: fuelling insecurity, and using it to keep them in their place. It’s hard to be assertive when you’re constantly terrified of getting one tiny thing wrong and being publicly humiliated for it.

If the only victims of such warped expectations of perfection were women paid handsomely to appear on screen, that would be bad enough. But these expectations filter down so alarmingly fast through the culture. Complimented a couple of years ago by a female reporter on the strapless dress she was wearing, the actor Jennifer Lawrence responded by tugging nervously at it and apologising because “I know I have armpit fat, it’s OK … armpit vaginas, it’s awful!” And the reporter responded in the self-deprecating way women automatically do, by tugging at her own dress and saying that now she was worried about her arms. What lesson does a watching teenage girl draw from that?

Somehow we need to get across to girls that this is bonkers, unreal, insane

From size zero to the “thigh gap”, or having legs so stick thin they don’t touch in the middle, today’s freaky A-list neurosis so easily becomes tomorrow’s fitness blogger’s goal, and next week’s impossible aspiration for your daughter. This stuff is infectious, and it stops being a frivolous issue when over half of British teenage girls say they’re unhappy with their looks, and when a smaller but still heartbreaking number feel driven to starve and punish the flesh that they have begun to see as repulsive.

Somehow we need to get across to girls that this is bonkers, unreal, insane: twisted norms that have nothing to do with their own lives or with the boys they will encounter. They need to know there’s no party worth being “red carpet ready” for, if that means systematically eliminating every last fold and crease. They don’t need any more “insider” fashion tips. If anything, this is an industry that needs to hear a bit more sanity from the outside.

For the truth is that audiences don’t care quite as much as performers have been made to think. The world wouldn’t end if actors came to premieres flaunting actual creases where their arms join their bodies. Frankly, they could show up in jeans and it would look refreshing. The only real ugliness on display here is buried deep within an industry that long ago jumped the shark when it comes to norms of female beauty. And that really is the pits.

• Gaby Hinsliff is a Guardian columnist