The actress Anna Friel, a 36-year-old mother with the slender frame and glowing complexion of a genetically blessed teenager, has revealed the rather extreme measures she takes to preserve her youthful looks.
First, there is the "master cleanse", which involves replacing solid food with numerous cups of a mixture of maple syrup, cayenne pepper, lemon juice and water. For many of us, that sounds like a nasty beverage a cruel older sibling might have tricked us into drinking, once, as a gullible child. For celebrities, it is the new elixir of hope.
"I've been drinking it for two months and feel so much better," Friel said. "And my skin has really benefited. If you're vain, as you get older you start thinking, 'I've got to do everything I can to save my skin.' I've tried everything."
To date, she says, she has experimented with the "vampire facial", in which blood is extracted from her arm and strategically reinjected into wrinkles. And before big events, she has a facial with a rejuvenating Cryoderm machine, whereby the skin is heated up, only for the temperature to be dropped to freezing again. She "felt sick" recently when she discovered a couple of grey hairs.
While Ms Friel certainly looks good for her age – or any age – it seems like an awful lot of high anxiety, expense and hard work on top of an already busy career.
She is not the only well-known woman whose war against ageing seems gradually to have ratcheted up to epic and wacky proportions. Victoria Beckham is rumoured to favour the brightening "bird poop facial", which uses nightingale droppings in the mix.
For the Oscar-winning actress Gwyneth Paltrow, 40, the business of attaining a rock-hard yet lithe body has come at times to overshadow her big-screen success. Paltrow is a devotee of the Tracy Anderson Method, devised by a personal trainer whose techniques, she says, have now given her "the butt of a 22-year-old stripper".
The star, who has just published her second healthy-eating cookbook, recently revealed how a panic attack sent her to Dr Alejandro Junger, who "recommended that I cut out basically everything: dairy, sugar, gluten, anything processed. I was like: 'What the –– am I going to eat now?'"
Perhaps a thick shake made from almonds, blueberries and curly kale. Junger – a Uruguayan with a blindingly white smile – is the author of Clean: The Revolutionary Program To Restore The Body's Natural Ability To Heal Itself. On his website, he and his equally bright-eyed team share their personal raw "shake recipes" with a sense of almost evangelical zeal.
Once, motherhood meant that a woman could take her foot off the glamour pedal for a while, in a forgiving setting where a dash of lipstick counted as "making an effort under the circumstances".
Not any more: to the world's most feted singers, models and actresses, pregnancy and birth is a kind of assault course that one is obliged swiftly to emerge from tougher, thinner and more aggressively sexy than ever.
Since the singer Beyoncé had her daughter Blue Ivy last year, she has embarked on a military-style exercise and nutrition regime to get back to a body that can slip into a tight, gold corset and strut on stage without embarrassment.
While Beyoncé is still only 31, even stars over 50 are expected to defy any signs of ageing: at 54, Madonna's diet and workout routine is notoriously relentless, while 52-year-old Julianne Moore – considered one of Hollywood's more natural beauties – described her terrified realisation that she had to start "training" when she was nominated for a Golden Globe: "I did this . . . juice thing. I've never done one before, but I was desperate."
Further up ahead, in the rockier territory of the mid-70s, Jane Fonda has frankly celebrated her debt to her plastic surgeon and the buoyancy of her sex life.
While most famous women now admit at least to having tried Botox, fewer will freely discuss more radical procedures. Yet the world of plastic surgery beyond the "injectables", is a roaring, albeit discreet, trade in face-lifts that have become ever more sophisticated and subtle.
Celebrities, of course, have always been obsessed by preventing signs of ageing, for practical as well as psychological reasons: when your face is your fortune, wrinkles can hit you in the bank account. Marlene Dietrich encouraged her hairdressers to pull her hair tightly back and use carefully concealed surgical tape to perform a home-made facelift.
Beautiful women in Hollywood have long dreaded the moment when the offers to play the mother rather than the ingénue start trickling in: the difference is that, today, there are many more surgical or quasi-medical "solutions" that promise to arrest the process.
In recent years, however – thanks to a lucrative anti-ageing industry – celebrity anxieties have been democratised: a range of high-street salons now enable any woman with sufficient funds to join in, while mass-market magazines puff the latest medical and surgical procedures in a style that they were wary of a decade ago.
In the US, some have strongly criticised the feverish combination of science and quackery that characterises the multi-billion-dollar anti-ageing industry. Arlene Weintraub, author of Selling The Fountain of Youth, has attacked the questionable science and ingredients behind many of the latest miracle "cures", pills and fad diets that treat ageing not as a natural process, but as an illness. In some cases, she argues, they may even be dangerous, particularly those involving poorly regulated hormone replacement therapy.
It is understandable that the baby-boomer generation wishes to grow old in a different style to their parents. But for a minority of women, a fear of ageing is blotting out enjoyment of life in the moment.
There has long been a subtle difference between the view of ageing in the US and in European countries such as France. In the US, it seems, the goal is often to look younger: in France, a country known for celebrating the older woman, the beauty salons are still busy, but the goal is more to look well for one's age: actresses such as Catherine Deneuve (69) and Juliette Binoche (49) are still celebrated for their allure.
Do men judge women for getting older? Not, perhaps, as harshly as women themselves do: I have heard trenchant male admiration expressed for Helen Mirren, Judi Dench and Christine Lagarde, all of whom project an image of confidence and style.
The ceaseless battle for youth seems to stem more from a fierce, competitive perfectionism in the female psyche, and every woman draws her own line on where to stop.
But I wonder if, when death approaches, many of the most ardent anti-ageing warriors might one day look back and wish they had devoted more time to relishing the life they had.