Belle Gibson's story sparks one question: why would a person do that? Dr Marc Feldman knows.

"None of it's true."

Those were the words so many had been waiting to hear from the lips of Belle Gibson. 

This was a woman who'd earned more than $420,000 and more than 200,000 social media followers based on claims she had treated her terminal brain cancer with diet and lifestyle changes. A woman whose popular app, The Whole Pantry, was picked for the launch of the new Apple Watch, who'd secured a book deal, won awards, and inspired countless cancer sufferers to shun conventional treatment.

But by the time she sat down with The Australian Women's Weekly in April 2015, her empire was already beginning to crumble.

The previous month, Fairfax journalists uncovered that, while Gibson claimed to have donated $300,000 from app sales to charity, no money had been handed over. In fact, her entire story was in doubt. Even her illness.

Then, finally, came the admission. The cancer, the self-healing...

"None of it's true," she told AWW journalist Clair Weaver.

"I am still jumping between what I think I know and what is reality. I have lived it, and I'm not really there yet."

The biggest question. Why?

Gibson's deception made headlines around the world, as the press and the public tried to understand one thing: why did she do it?

The mother of one has offered little explanation for her deception in the years since. 

In the AWW interview she pointed only to a "troubled" childhood, she said she never met her father and claimed that, from a young age, she was given the responsibility of caring for her Multiple Sclerosis-suffering mother and a brother with Autism Spectrum Disorder.

(Her mother and brother disputed the claims in a follow-up interview, with the former declaring: "Belle never cared for me, her brother is not autistic and she’s barely done a minute’s housework in her life... She’s just a girl who always had ideas above her station.")

Then, in a subsequent interview with 60 Minutes, Gibson alleged that she had been falsely diagnosed with brain cancer by an alternative medicine practitioner in 2009 — a diagnosis she said she wholeheartedly believed until a hospital scan in 2011 proved otherwise. She described the revelation as "traumatic". 

Still, despite knowing she'd never had cancer, Gibson launched The Whole Pantry two years later peddling her natural healing story. 

Did you miss @TaraBrown60's astounding interview with Belle Gibson last night? WATCH: http://t.co/kcHlbYRfzqhttps://t.co/rUJrHTZZmk

— 60 Minutes Australia (@60Mins) June 29, 2015

Gibson's case caught the eye of Marc Feldman MD, a clinical professor of psychiatry and an adjunct professor of psychology at the University of Alabama. He's studied medical deception for over three decades.

Speaking to Mamamia's new podcast Extraordinary Stories, which delves into the Belle Gibson saga, Dr Feldman explained that in classical medical deception the person knows precisely what they're doing. 

"They may not know why, but they know [they are doing it]. And you can tell this from the considerable planning involved in their actions," he said.

"And so they figure out lies that are going to be convincing, that people may not check on. Because the most audacious lies, like having cancer, are sometimes the ones that are automatically believed."

After all, who would lie about something like cancer?

Even Penguin, the publishing house that released The Whole Pantry cookbook, conceded it "did not feel [it] was necessary" to fact-check Gibson's claims about her illness, and later agreed to pay $30,000 to the Victorian Consumer Law Fund as a penalty.

Several other companies and media outlets were duped, too, despite allegations from people in Gibson's life that she a long history of deception.

One accuser wrote an email to Australian media outlets in 2015 that read in part: "I’ve known Belle since her childhood (and am close with her mother) and she has always had a problem with fabricating stories from nothing on a regular basis.

"She got so tangled in her own web of lies living in Brisbane, she moved to Melbourne to start a new life of lies — 'the cancer lie' this time."

Listen: Extraordinary Stories takes a deep dive into the case of Belle Gibson, the wellness entrepreneur who built an empire on lies. (Post continues below.)

Dr Feldman is the person who coined the term 'Munchausen by internet' back in 2000, a syndrome that sees people fake an illness online in order to get attention and sympathy from others.

These days the term Munchausen has been replaced by 'factitious disorder'. This is a recognised mental illness in which a person either feigns, exaggerates, or actually induces illness in themselves in order to get attention, care, nurturance that they feel unable to get in any other way,

While it's a feature of some medical deception cases, Dr Feldman argues it wasn't that simple in Belle Gibson's.

"What's interesting about Belle Gibson and so many patients in my practice is that I don't think she has a single diagnosis. Sometimes medical deception in one individual can come in multiple forms, and I think that's the case here."

While he hasn't treated her, he points to another form of medical deception called malingering.

"Malingering is not a mental illness by any means. And no one says it is," he said. "It's a behaviour in which a person, again, feigns exaggerates or induces illness in oneself or in another, but their goal is external and tangible.

"It's usually money, disability payments, it can be narcotic medications, it can be evasion of criminal prosecution, evasion of military service."

He suggests both may be true in Gibson's case.

"I think she is clearly a malingerer. That is, she's been after money and other things like that," Dr Feldman said. "But she's also been after fame, notoriety, and the love of people who might not otherwise notice her at all. So I think she has both factitious disorder and is a malingerer as well."

Belle Gibson battles the media scrum outside court in 2019. Image: AAP.

In September 2017, Belle Gibson was fined $410,000 for her false claims about donating a portion of the proceeds from her app to charity. 

However, the court later heard she was unable to pay because she was in $170,000 debt and had just $5000 to her name.

In January 2020, police raided her Melbourne home, seizing assets to recoup the still-unpaid fine.

She's avoided the spotlight since. And giving her answer to that all-important question, the one so many of her colleagues, friends and once-loyal followers have been left asking. 

Why?

Extraordinary Stories: Belle Gibson is available to M+ members via the homepage or the Mamamia app.

Feature image: AAP/Mamamia.