I first catch sight of Demi Moore crouching on the floor in a hotel corridor, coal-black hair fanned across her back. She’s talking in a peeping high voice, which is confusing: Moore’s husky pitch is her trademark. What I can’t see until I’m close are the tiny dogs she’s playing with. When I say tiny, Moore’s chihuahua, Pilaf, is a thing unimaginable until you see her. Thimble small. How-is-that-even-a- dog small. Moore is overseeing an introduction to Bruno, a puppy belonging to one of the comms team I’d met earlier and who was, until Pilaf, the smallest dog I’d seen. Bruno now looks like the Hulk. The dogs’ characters are compared, their habits, their fur; they snuffle each other, squeak and squelch (their version of barking). Finally, Moore scoops Pilaf from the floor – bye Bruno – and the little angel joins us for our interview. First on her lap, then on the PR’s lap, then investigating the sofa and my bag (don’t wee there, Pilaf).

Pilaf’s teensiness initially distracts me from noticing how Moore herself is fine-boned and delicate; poised like a Modigliani in her chair and so toned I can see taut bands of muscle sweeping from her clavicle. Her dark hair forms two straight varnished curtains that hang to her waist. She wears a structured brown dress and killer-red nail varnish and uses hand gestures so voluminous that if you witnessed our conversation with the sound off, you’d think she was describing a series of explosions.

Why am I focusing on the way she looks? Because we are here to discuss her film The Substance, which is at once a body horror and a funny, furious satire of our obsession with youth and appearance.

Moore, 61, plays Elizabeth Sparkle, a lonely has-been celebrity who is axed from her aerobics show on her 50th birthday by TV executive Harvey (Dennis Quaid). Over lunch Harvey reminds her, as all women must be reminded, that a woman’s value lasts only as long as her fertility. That same day the offer of an injectable cell-reproducing serum that will cause the body to generate a shiny young version of itself, with some small-print caveats, seems timely and all too tempting. It’s a Dorian Gray plot, less absurd, perhaps, with the current hysteria around semaglutide (the weightloss drug sold as Ozempic and now thought to slow ageing). The film is hyper-real, the sound sharp, the overall effect queasy.

Moore – who has spent her adult life having her anatomy scrutinised for signs of plastic surgery – did not mind that French writer/director Coralie Fargeat thought she was “perfect” for the role. She did not mind that she would be required to strip down for full-frontal nude scenes. Or even that her regenerated self “Sue” would be played by Margaret Qualley and that she’d therefore be compared with the 29-year-old in some hyper-sexualised, male-gaze satirising bum and boob shots. “Fully intrigued,” she sat down and read the script. “I thought, ‘OK, this could either be really amazing or an absolute disaster.’”

Although she’d watched Fargeat’s 2017 debut Revenge – “so I understood her sensibility” – Moore was unfamiliar with body horror and at times she found it “head spinning”. One person suggested she think of it as “phantasmagoric”. “I was like, ‘What is that?’ Someone else said, ‘Well, The Fly is considered body horror.’” Early in The Substance, the subject of that film is neatly referenced, floating in a glass of wine. Actually it draws from across the comic-horror-fantasy board, not least Carrie (1976), Freaky Friday (1976), Death Becomes Her (1992) and in subtler ways, Moore feels, All About Eve (1950).

The thing that really grabbed Moore – “obviously” – was “the circumstances of a woman in the entertainment industry who’s facing rejection and deep despair. Everything in her life that seemed meaningful is being ripped out.” And beyond, “What really struck me was the harsh violence against oneself. It’s not what’s being done to you, it’s what we do to ourselves.” Traditional horror, she says, merely terrifies, “whereas there’s a depth to the exploration of our psyches, our inner dialogue, that body horror seems to amplify”.

Even after filming she had no idea if it would appeal to audiences. When she settled into the 2,000-seat theatre at Cannes to watch the final cut in May, she was looking round thinking, “Is it going to resonate? Is it going to connect? Are all the grotesque parts going to translate? Or be like, too off-putting?” The crowd, according to reports, “went wild”.

How does she feel now? She smiles. “I’m still in shock.”

The Substance has been described as Moore’s “comeback”, which she finds baffling as, “it’s not like I’ve really left to come back”. It is true that before this film she had been wondering if the acting side of her life had – she stalls – “not ended, but like, was it ‘complete’?” She does a lot of this linguistic repackaging, as though gently guiding herself away from the cliff edge. “I’ll leave others to, like, identify or label it however they need to.” She adds: “As Michelle Yeoh said, ‘You were just on pause!’”

A reminder: Demi Moore was the dangerous beauty of 80s and 90s cinema, the wild and surly rebel of the original Brat Pack movie St Elmo’s Fire (1985) and star of Ghost (1990) and A Few Good Men (1992). It’s hard to imagine today the almighty fuss over her nude and pregnant cover of Vanity Fair, shot by Annie Leibovitz in 1991. It was called “pornography”; newsstands refused to stock it. In an era where the gender pay gap is front of mind, it’s also maddening to remember that she was dubbed Gimme Moore for negotiating $12m for Striptease (1996), when her then husband Bruce Willis was merrily cashing nearly double that for Die Hard 3 (1995).

For much of the 2000s, Moore was dogged by tabloid gossip about her marriage to Ashton Kutcher, whom she met when he was 25 and she 40. The age gap inflamed the savage obsession with her appearance – whole articles were devoted to how much surgery she’d supposedly had, including a guessed-at “knee lift” because, well, doctors with newspaper columns zoomed in on her image and decided she didn’t have enough “kninkles”.

Meanwhile, Moore and Kutcher holidayed in the Caribbean, in Mexico, spent endless days in bed. Kutcher dotted the house with Post-its telling her how magical she was, how much he loved her, until he didn’t. There were rumours of meltdowns, exclusives on his one-night stands – one such report in 2011 appeared on her phone as a Google alert while she was having her hair and makeup done for the premiere of Five. For seven years she kept a relatively low profile, until in 2019 she “shared” as she puts it, Inside Out, her dynamite memoir ghosted by the writer Ariel Levy. It was an instant New York Times bestseller.

In it, Moore described her turbulent peripatetic childhood with a suicidal bipolar mother and cheating, violent father – later revealed not to be her biological parent after all. She recounted being raped at 15 by a family friend who asked her afterwards how it felt “to be whored by your mother for $500”. She left home at 16, married at 17, made her first film at 19. She told of her issues with alcohol and cocaine, which she had for breakfast – “I nearly burned a hole through my nostrils” – and which was supplied by, among others, her dentist.

She got clean in 1984, but eating issues followed, fuelled by executives telling her she needed to lose weight. She was on the frontline of relentless Hollywood sexism. One producer couldn’t understand why Moore’s character didn’t have sex with Tom Cruise in A Few Good Men. “If Tom and Demi aren’t going to sleep together, why is Demi a woman?”

Pretty much all her partners – including fellow Brat Packer Emilio Estevez – were allegedly unfaithful. Kutcher blamed his flings on the “blurred lines” of their marriage (the couple had threesomes, experiences that Moore writes filled her with shame). After nearly two decades of sobriety, he also reintroduced her to alcohol saying, as he enjoyed a glass of red one romantic evening, “I don’t know if alcoholism is a real thing – I think it’s all about moderation.” Moore wished she’d thought, “This is a kid in his 20s who has no idea what he’s talking about.”

In January 2012, just shy of 50, Moore was at an all-time low. Kutcher had left, post-marriage cordiality with Willis had soured, her daughters barely spoke to her, her career seemed to be over. She found herself in the midst of an existential reckoning. If this is life, she thought, “I’m done.” Her memoir opens with a scene at home in Los Angeles: friends are partying around her and she listlessly joins in taking hits of nitrous oxide and smoking synthetic pot, known as Spice. Next, she was having a seizure and someone was screaming, “Call 911!”

It was gripping to Fargeat, all of it, but the director was particularly caught by Moore’s relationship with her body. In the 90s and noughties, women were not attractive or desirable unless they were thin, Moore tells me. Thinness was the vital component, explicitly and implicitly in film, fashion and the media. But what Fargeat kept coming back to was the decades of abject torture Moore put herself through with frenzied starving and exercising to achieve this ideal. “What I did to myself,” is the way Moore explains it. “What I made it mean about me. Really looking at that violence, how violent we can be towards ourselves, how just brutal.”

As an aside she says this idea is 100% relatable to men, too. “Self-judgment, chasing perfection, trying to rid ourselves of ‘flaws’, also feeling rejected and despair, none of this is exclusive to women.” She references a scene where Elizabeth is asked on a date but keeps finding fault with herself in the mirror. “We’ve all had moments where you go back and you’re trying to fix something, and you’re just making it worse to the point where you’re incapacitated. We’re seeing these small things nobody else is looking at, but we’re so hyper-focused on all that we’re not.” She takes the idea further. “All of us, if we start to think our value is only with how we look then ultimately we’re going to be crushed.”

In 2021, there was uproar over her appearance when Moore walked the runway for Fendi. Perhaps it was overenthusiastic makeup contouring, or perhaps she was caught by unflattering spotlights, or perhaps she’d had “work”; for whatever reason, her cheekbones appeared unnaturally severe. “Yes,” she says, acknowledging that this happened. She speaks carefully, deliberately. “Look, we are living at a time of great judgment. People can anonymously judge one another really in cruel ways. I feel [this kind of judgment] is a reflection of someone’s own unhappiness and/or a way to boost their own sense of self. When those things happen, I have learned to just let it roll.” Ultimately, she adds, “It’s what I make it mean about me. If I give it a lot of weight and value and power, it will have it. If I don’t, it won’t.” In other words: mind your own business.

Besides, the frantic scramble to find a miracle to transform each of us into “a better, younger” version is felt by everyone, she says. “We’re all exposed, we see stuff every day – ‘Oh, this vitamin, this thing, this thing’ – there’s stuff everywhere.” But in the film, what does Elizabeth do with this shiny new opportunity? She simply retraces the steps of her own life. Yes, her young “self” goes back to the TV exec, she goes back to the aerobic show. Moore loves this about the script, that it’s shoving into our faces what we apparently don’t know: that given the same chances all over again, we will seek the same crappy validation and make the same dumb choices. “Because, if you think about it – and obviously it would have been a different movie – she could have said, ‘You know what, I’m going to produce my own show. I’m going do X, Y and Z differently.’ But no. The need to have that same validation is there until we break our patterns.” She sighs. It’s a sigh for all of us.

Moore has searched everywhere for answers: she turned to Kabbalah with Madonna and Guy Ritchie, consulted tarot cards, psychics and had endless therapy. She even keeps an open mind about reincarnation (we spend five minutes discussing Surviving Death, a Netflix series investigating the afterlife). But one of the most powerful things said to her, she says, was when she was complaining to a tarot card reader that she never felt good enough. The woman told her flatly, “‘Oh, well, you’ll never be good enough.’ I was so shocked, like that was such a harsh truth. She said, ‘But you can know the value of your worth. You just have to put down the measuring stick.’” She says she thinks about this “gem of wisdom” when she is tempted to “compare and despair” while, say, scrolling social media.

“And while I can intellectually comprehend it, like many things, it’s a constant effort to work on it. You catch yourself when you’re being in a state of like …” Her hands mime her despair. “And you’re like, ‘No, I need to focus on being the best me.’ I remember my daughter saying, ‘I want to quit wasting time focused on all the things that I see as not good or not how I want, because it’s taking away from celebrating all the things that I am.’”

So then, did it change her, making the film? “Definitely. It was a very hard film, very raw; very vulnerable to make. But at the same time liberating. I had less pressure than Margaret, because she had the added pressure to look amazing. I degrade throughout and I knew going in that I wasn’t going to be shot in the most glamorous way, or with the edges softened. In fact, the opposite. But there was something freeing about that.”

In the film, the younger and older self must share one life, alternating every seven days. Inevitably they disapprove of what the other is doing with their time. The split becomes war, older versus younger, with all the implicit mother/daughter dynamics therein. Unlike the fairytale trope, the older self is not the evil witch. It’s the younger self who is the self-obsessed wicked little monster. Moore concedes with a knowing smile, that our younger “selves” are, indeed, “a little bit more narcissistic, a little more, ‘everything is about me’”.

That said, she is heartened greatly by the “beautiful shift” in the way young women navigate their lives. She loved watching Qualley on set, for instance. “I learned from her. Learned and appreciated the confidence she had in asking for what she wanted, without being apologetic, in ways that made me go, ‘Wow.’ Back in the day, a woman being strong was often seen as a bitch. Difficult. So how great is it that at such a young age she can be in that place and not need more years to get there?”

Moore’s daughters (she has three with Bruce Willis – Rumer, 36, Scout, 33, and Tallulah, 30) have only seen the trailer, having decided to wait and watch it all together at the Los Angeles premiere on 17 September (Rumer told her, “Oh my God, I’m terrified”). Pilaf, currently barking at my coat, will probably go, too, as she is the only one of Moore’s nine dogs she takes almost everywhere.

I ask what her life looks like now her children have grown up, and she says it’s interesting living alone, admiring the landscape of life in her 60s. She still lives at the ranch in Hailey, Idaho, where she and Willis raised their children (Willis, 69, has a place nearby with his wife and two more daughters; the family is coping with his diagnosis of frontotemporal dementia). She says there’s a joy in waking up every morning and thinking, “What do I want to do?” That she doesn’t have to orbit anyone else’s schedule, that if she liked she could get on a plane and spend the weekend somewhere of her own choosing, and that she didn’t have to feel uncomfortable or guilty or anything about it. “That was a real learning curve for me, an awakening.” She found herself expanding horizons in other ways, asking not just what she wanted to do, but who she wanted to be. “Like, who am I as a woman? Not as a mother, or wife, or actor. As just a person?”

She realised she’d been conditioned to believe that when you grow up your life dulls and, to some extent, she’d bought into that. “A lot of people believe – as the film says – that a woman’s value goes when her fertility ends, and that when your desirability ends, your passion in life ends, too. For so long that was a truth not spoken overtly, but silently. And I’m realising that, actually, that’s not true.”

Now she sees a completely different future, one that she gets to define, one that will include more acting, including a St Elmo’s Fire reunion with the original cast; more producing (among her previous credits are all three Austin Powers movies); maybe another memoir, “when I’ve lived a little bit more”. And not just because she likes her life and all the possibilities it presents, but because she wants to reflect a positive attitude to ageing back to her daughters; to show them all that is available to them, too.

“So, if I want to open that door for them, I need to be willing to step out,” she uses her hands to gesture the movement. “I’ve never been at this exact point in my life before, so I don’t know what it is or where it’s going. But I know that I want to continue to keep growing as a person. I want to keep learning. I want to keep challenging myself, pushing myself out of my comfort zone, which isn’t something any of us love, but I always know that I am better for it when I get to the other side.”

“Do I date?” Moore repeats my question, looking briefly to the ceiling. “I don’t know. It’s not really been where my focus is, I’ll say that. Particularly in the past four, five years, my focus has been to lean into my work.” She adds that she wanted to give her craft more attention, to refine and finesse the part of her that fell by the wayside when she “chose not to work for a long time”.

She says she doesn’t need a relationship to complete her. “It’s not about not being interested in dating. It’s more about realising that I’m now in a place that’s much more about choice as opposed to feeling that there’s any kind of lack.” She thinks there is truth to the idea that men need women more as they age and women need men less, because women are “in many respects hardier; stronger. But I also think that we are often – not to generalise – but we are often caretakers. So, I think as we get to that place of greater independence and freedom in our later years, I don’t know if we …” – she is careful again with her phrasing – “seek to take on the responsibility of others. We have, for the first time, real room to move without the weight of others.” Yes she enjoys her time alone, “But I also enjoy being with others … I have full faith, because I think we’re a communal species.”

I ask whether she still has her 2,000-strong doll collection (it was reported that Kutcher found them creepy). “I do. I haven’t added to the collection in a long time, but most of them are one of a kind, what are considered ‘art dolls’.” She had intended to create a museum because some are extraordinary works of art, including by the French artist Anne Mitrani. But dolls are not all she collects. “I have a collection of both oversized items and miniatures. My particular penchant is for oversized things that are real, meaning that they’re exactly how they might be made in real scale, but oversized. And so I have a 6ft butcher’s knife, like a kitchen knife, that an artist did, and it’s literally a real knife.”

What are the mini things, aside from Pilaf? “There’s a variety. I have a pair of 3ft scissors and then I have miniatures. I have oversized boxing gloves. I have an oversized clipboard. The idea of scale is interesting because we get very accustomed to, like, ‘this is the size,’” she picks up a cup, “and that’s normal. But what is normal? And so, when you see things in a different scale, it affects you differently, and the oversized items in truth just make me laugh.”

Is she a real life Alice in Wonderland? “Oh, that is truly like what I step into. I have a very childlike quality. I think it’s important. What was that quote – ‘Play like a child?’” She can’t remember it. “It’s important not to lose that sense of innocent joy. I look at my granddaughter” – Louetta, 17 months – “and I see the awe in such small little things. And it’s that beautiful reminder of not taking things for granted.”

A strong theme in her personal philosophy is to avoid reproach and recrimination. “So often there’s this idea that we want to blame the outside. We tend to see ourselves as the victim. We can be like, ‘But this is happening to me.’ I am a big believer in the idea that everything in life is happening for me, not to me. And applying that lens to my personal life, I find, is really a game changer. That doesn’t mean things aren’t difficult, painful, disappointing – all of that can still exist when it’s happening for you. It is just looking at it through the lens that is saying, ‘What is this trying to give me?’ so that I don’t miss that opportunity.”

In that vein, she doesn’t want to blame her terrible parents. Or her succession of cheating partners. Or the way that the press or Hollywood have treated her. Perhaps she doesn’t feel that she can change anything, ultimately. Except with acting, which she allows to speak for itself.

Oh wait, there is one exception to Moore’s ethos of personal responsibility: Pilaf. When the dog gets disruptive again and starts making her little Ewok grumbling noises, Moore is baffled by her behaviour. “She normally doesn’t bark. I don’t know what she’s barking at.” And then it dawns on her, and for one dizzying second, I fear she’s going to say it’s me, that Pilaf hates me. “No, no,” whispers Moore. So who is to blame? “I think it’s him, the other little dog: it’s Bruno.”