Overnight, she went from being a movie star to a sort of Noughties version of Linda McCartney, all dressed-down hair and peasant tops.
Gwynnie (as by then she had become known) wafted around popping out angelic-looking infants and calling them silly things like Apple.
She was photographed gazing adoringly at her husband and generally enjoyed a lifestyle we all outwardly disapproved of but secretly longed for.
As ever with the things we envy, it became fashionable to deride poor Gwynnie and her beatific existence for its insufferable smugness. But she didn't care. In fact, she loved her life so much she wanted to share it with the rest of the world.
When she launched her lifestyle super-blog Goop (a name derived from her childhood nickname) in 2008, encouraging readers to "nourish the inner", we all fell about laughing. Seriously?
Who was this spoilt celebrity to tell us how to live our lives, what to eat, how to exercise, how to raise our children, what to wear? What could she possibly know about the everyday struggles of real woman, her with her perfect teeth and golden hair?
Yet, here we are eight years on, and Gwyneth is as clean and serene as ever. Her website attracts four million views per month and more than a million subscribe to her weekly newsletters. Her recipe books - the latest of which has just been published - sell like gluten-free, no-sugar hotcakes.
Millions of women hang on her every word, imitating her in dress, style and philosophy. She single-handedly launched the so-called "clean food" revolution, inflicting "courgetti- spaghetti" on a whole generation of blameless children and makes us all feel like unhealthy super slobs if we don't detox in January.
So who is the real Gwyneth Paltrow? Ditsy celebrity - or hard-nosed, calculating businesswoman?
My money's on the latter. She may be blonde, skinny and over-fond of flaky beauty treatments, but she's nobody's fool. She's a businesswoman every bit as canny and as ruthless as Donald Trump. Let's face it, you don't get to become a global internet brand and lifestyle guru by chance.
In fact, there is many an aspiring politician who could learn a thing or two about Gwyneth's expert self-branding. Just the right balance of vulnerability, a smattering of self-revelation, a few carefully chosen causes, passion, compassion - and an army of evangelical followers ever-eager to espouse the Gwynnie way.
On the surface she may appear to be away with the fairies, but the truth is that every bonkers and controversial action or statement always boosts her profile - and her bank balance. Here's how she did it.
Bikini selfies mean big bucks
Truth is, Gwyneth is most at ease in a pair of jeans and a T-shirt, or in some stylish gym ensemble.
She has a great figure, but is strangely lacking in sex appeal, which is why, when she suddenly started wearing stripper heels and micro-mini-skirts coupled with vampish make-up when she turned 40, we all slightly choked on our granola.
Thankfully, that phase didn't last long. Lately she's had a penchant for unflattering nude catsuits. But why should she care?
She may wear some horrors, but ask any top designer which celebrity they want to dress on the red carpet and Gwyneth will feature on every list. From Valentino to Versace, Stella McCartney to Karl Lagerfeld, they all want Miss Paltrow as their muse.
As well as "consciously uncoupling", Gwyneth also has a penchant for "consciously unclothing".
She loves to pose in her bikini and smalls on her Instagram - and look what it leads to: lucrative endorsement deals with Max Factor as well as with designers Hugo Boss, Coach and Tod's. She even plugged Spar ready meals in Austria.
Keeping in with the rich and powerful
Anyone who tells Madonna to take a hike deserves a gold star in my book, but in a rarified celebrity universe where most friendships are based on power, it was nevertheless quite a gutsy move.
In true A-list style, they fell out over their personal trainer - Tracy Anderson. Gwyneth introduced Madonna and Anderson, but was later said to be angry at the brutal way Madonna ditched Anderson and froze her out.
But, as ever, Gwyneth was on the money: Madge's star is fading and just look at the rich and powerful pals Paltrow has kept.
She's best friends with Oprah Winfrey, Beyonce, Cameron Diaz, Stella McCartney and movie mogul Harvey Weinstein.
She is (and always was - her godfather is Steven Spielberg) one of the best connected women in Hollywood.
A ruthless recipe for success
She once said that she'd rather take crack than eat processed cheese, and her stance on healthy eating has at times verged on the insane.
Only a few weeks ago she extolled the virtues of a NZ$280 breakfast smoothie, which comes complete with a sprinkling of something called Moon Juice Sex Dust ($86 for 2oz, available from - you guessed it, Goop.com).
Such has been her dedication to the organic, the spiralised, the free-from-dairy, wheat, gluten, sugar, salt and joy, there are many who credit her with (or blame, depending on your point of view) kick-starting the whole clean-eating craze, which has now grown into a multi-billion-pound industry and created its own constellation of superstar food bloggers, from Amelia Freer to the Helmsley sisters.
Sales of kale boomed by 38 per cent after Gwyneth featured it liberally in her first recipe book.
One of Gwyneth's greatest talents is her ability to scent a change in the wind, and she seems to have sensed a turn in the weather.
Her latest recipe book (her fourth) includes a recipe for spaghetti alla carbonara, complete with pancetta, egg yolks and Parmesan, something that until recently would have been unthinkable in the Gwynnie universe. She has even confessed to letting her children eat the occasional Oreo biscuit.
Muscling in on the fitness scene
Gwyneth certainly works hard to maintain her slender figure, from hot yoga to sweaty dance sessions.
But as ever with our girl, she likes to take things one step further, and has recently gone into business with celebrity trainer Tracy Anderson, whose famous but gruelling "method" is responsible for many of the hard-bodied stars you see walking the red carpet.
The pair are partners in a chain of gyms, and even have a range of prepared food under their joint names - meaning that while Gwyneth keeps trim, her bank balance is filling out nicely.
Being her, of course, they also run a woman's charity together - you know, just to offset some of that filthy lucre.
Crank beauty tip or a marketing trick?
A strict advocate of natural remedies, Gwyneth eschewed the needle and the knife in favour of pretty much any kind of ancient shamanic gobbledegook you can think of.
High points include her claim that women should get their intimate areas steam-cleaned, and her recent ravings about bee sting therapy "apitherapy" - the belief that letting bees sting you can help to calm inflammation and heal scarring on the skin.
It's hardly a coincidence that the bee silliness came just as she launched her own range of skincare products, which have got beauty bloggers and fans gushing lyrical about their miraculous properties. The products are perfectly nice, of course, and contain lots of good ingredients - although they'll set you back a pretty penny.
But at 43 and with her saintly lifestyle, Gwyneth is not yet at the stage in life when things really start to go south.
Let's wait until she's menopausal, shall we, and see whether she still advocates an all-natural approach?
In the meantime, of course, there's still plenty of money to be made from selling fancy oil and water infusions.
Hard-nosed sense behind loopy goop
Her website is loopy - an online shrine to crystal healing, detoxing and mindful thinking.
There are the insanely expensive gift guides (a $4,000 juicer anyone? A $2,000 pair of statement earrings?) and her $500,000 "must-have capsule wardrobes."
But there's nothing flaky about Gwyneth's ambition for the site. Right from the start, she showed she meant business by hiring one of the earliest e-commerce success stories, Seb Bishop, as CEO.
Bishop - who sold his online advertising company for Β£97 million back in 2003 - helped to establish the commercial bones of the project, creating an online marketplace that luxury lifestyle brands could trust.
It took a while to find its feet, but it's now on target to start making a profit.
A crack commercial team has been hired, shops are proposed and it's attracting big-name advertisers such as Chanel (which is notoriously web-phobic), while designers such as Valentino and Stella McCartney have produced exclusive ranges for Goop devotees.
Consciously uncoupling was good for business
Someone like Gwyneth was never going to just "split up" was she?
When the time came to announce the end of her 11-year-marriage, it was done in a way that was uniquely Gwynnie and in a manner intended to drive people to her Goop website.
A sunny picture of a smiling Gwyneth and Chris Martin sitting on a lawn appeared on the site beneath the headline "Conscious Uncoupling". In the statement the couple said: "We always will be a family and in many ways we are closer than we have ever been."
The phrase "conscious uncoupling" had been coined by psychotherapist Katherine Woodward Thomas, who believes that divorce can be a positive thing.
The world mocked but as Gwyneth said: "We broke the f****** internet!" Millions flocked to Goop just to read the statement.
As for the separation itself, the Martins gave us a masterclass in how to end a relationship in a civilised fashion. But then Gwyneth has always been strictly strategic about her relationships with men: she ditched both Brad Pitt and Ben Affleck, both of whom turned out to be heartbreakers and cheats.
Forget Oscars! she's sold out to earn movie millions
Despite early promise and an Oscar for her role in Shakespeare In Love at the tender age of 26, her acting credentials seem not to be a priority.Having eased up after her marriage to Martin and the birth of their two children, she's starred in more than her fair share of turkeys.
Mortdecai (with Johnny Depp) was a spectacular flop last year and absolutely savaged by the critics. Not to worry, though, as she seems to have set aside artistic concerns in favour of a lucrative blockbuster franchise, starring alongside Robert Downey Jr in the Iron Man series - one of the most successful in modern cinema, grossing over $2 billion at the box office.
Even then, though, she seized the opportunity for a bit of virtue-signalling, "speaking out" against the pay gap between men and women in the movies.
And she's right: she only earned $10 million in 2015, whereas her co-star, Downey Jr, netted an estimated $100 million. It's a tough life.
