Not Matthew McConaughey, though. Him she knows.

When I tell her I've got a morning interview with McConaughey, she's excited, even though it's only on the phone. Just the thought of that silky voice passing through the receiver into our home is enough.

It wasn't the first wave of roles that did it for her, from Linklater's Dazed and Confused to the leading man of A Time to Kill and Contact. And it certainly wasn't the wave of rom-coms, which almost killed his career just when it should have been soaring. No, what stamped McConaughey in my wife's consciousness was precisely what did it for so many others: that magical career rebirth that started around 2011 and reached its zenith a few years later with his turns as Rust Cohle in True Detective and the AIDS-afflicted rodeo rider Ron Woodroof in Dallas Buyers Club.

The latter won him a best actor Oscar in 2014, and now he's chasing the precious metal again as prospector Kenny Wells, the anti-hero of Gold.

McConaughey goes shirtless in Gold, as he does in so many of his movies. "So long as you live in a place where you don't have to wear a shirt," he tells me in that honey-dripped Texan drawl, "keep it off".

But this time around, those rippling pectorals – once described as looking like "a pair of toasted dinner rolls" – have given way to sagging man boobs. He's got a beer belly, too, and a thinning mullet. He even sports a wickedly crooked front tooth.

This, it's fair to say, is Matthew McConaughey as you've never seen him.

He's transformed before, of course; to play Ron Woodroof, he shed 21 kilograms, essentially by starving himself. "I'd have a Diet Coke, two egg whites in the morning, a piece of chicken, then another Diet Coke," he told the Mirror in 2014. "That was rough."

Putting on 20 kilos for Gold came a little more easily.

He ate, he tells me, "two or three burgers a day, the beer and the bread with the burger, right before bed. I didn't do all the ice-cream and stuff – I just wanted salt, meat, bread."

McConaughey shed 21 kilograms to play Ron Woodroof in Dallas Buyers Club. Photo: Pinnacle Films

It must have been kind of repetitive. "Honestly, I never did get tired of drinking a lot of beer and eating a lot of cheeseburgers. And I didn't get as lethargic as I thought I would. What I learned in those eight months is the only thing that makes you tired when you're indulging like that is the thought of quitting."

Gold is a fictionalised telling of a real-life scandal. The Canadian mining company Bre-X claimed in 1995 to have discovered a massive gold deposit in Indonesia; in fact, their chief geologist, Michael de Guzman, had been "salting" the samples he was sending for independent verification, lacing the barren rock with minuscule amounts of gold to make it look like they'd struck the mother lode.

... and put on 20 kilos to play Kenny Wells in Gold. Photo: Lewis Jacobs/Studio Canal

As the company's stock priced soared, its directors – including founder David Walsh – got filthy rich. When the scam was exposed, shares in the company became worthless, effectively robbing investors of billions of dollars overnight.

Kenny Wells is based on Walsh – who always maintained his innocence – but not slavishly so. When McConaughey first came across the project, about five years ago in his reckoning, Wells was still called Walsh, and the story was a lot more true to the details of the Bre-X scandal. But as the script developed the story morphed, moving back in time to the 1980s, the era of Oliver Stone's Wall Street.

That time shift allowed it to become, says McConaughey, a story "about what American greed meant at the end of that decade".

McConaughey, right, in the film that launched his career, Richard Linklater's Dazed and Confused (1993).

Once they'd decided to cut loose a little, "the approach was, 'OK, we don't have to tell this exactly how it happened. So we created a central female character [Kaye, played by Bryce Dallas Howard] and a love story, to which Kenny comes back at the end. And we were like, 'Well he doesn't necessarily need to be Canadian; let's make him a down-and-out guy in Reno'.

"It was just things to help tell the spirit of what really happened – a down-and-out dreamer who went and chased that dream, and then made it a reality – or didn't. Either way, the guy did something."

Perhaps the most significant result of this tweaking with reality is that Kenny Wells, for all his flaws, is a man with whom you can't help but empathise. And that's probably not something you would say about David Walsh, who fled with his ill-gotten riches to a tropical island.

Not that he got away with it entirely. "He ended up living in a mansion in the Bahamas, but he was in his own prison, keeping people away from him," McConaughey says. "He died [in 1998] of an aneurysm shortly after he evidently got hit with a large blunt object. Was that mining prospector justice?"

(Officially, Walsh died after suffering a stroke, just days after his assets were frozen by a court and his family put on a $3000-a-week stipend.)

Sans shirt, in Magic Mike. Photo: supplied

Walsh was a chain-smoking, beer-guzzling glad-handler, but having unshackled the character from the real man who inspired him, McConaughey didn't have to go that way. The body transformation, he says, was simply his way of understanding Kenny "from the inside out".

"I never set out thinking he needs to be fat," he says. "But boy, he sure was full. He was a consumer, of life – food, drink, love, loyalty, the buzz of pulling his scam off. All of it."

He says he modelled Kenny on men he met as a kid through his father, who worked in the oil business in Texas. "They were all in the oil pipeline business, working out of bars. They were trying, as my Dad would say, to 'get a lick'."

And shirtless again, in the rom-com Fool's Gold. Photo: Warners

These were hustlers – men, he says, "who were never going to have a front-row seat for the American Dream. They chipped a tooth, they went and bought Super Glue. They weren't people who looked in the mirror and considered how they looked or what their health was like. They were going full bore every day, saying, 'Today's going to be the day and I'm going to eat every bit of it'. And for most of them, today was never the day. They died without having their day."

As he says all this, I'm reminded of McConaughey's Oscar acceptance speech, that inspirational-cum-cringe-inducing spiel about how he is his own hero, but the hero him is a future version who will always remain just out of reach.

"Every day, every week, every month and every year of my life, my hero's always 10 years away," he said. "I'm never going to be my hero. I'm not going to attain that, I know I'm not and that's just fine with me, because that keeps me with somebody to keep on chasing."

It's aspiration personified. And if Kenny Wells is a little like that too, could it be that  McConaughey finds him in some way admirable?

"I find him incredibly admirable, because he's so pure," he says. "He is never about greed, to me – he's about pulling it off, proving the man wrong, no matter what it takes.

"The question at the end – was he innocent or was he not? – is a great question," he continues. "But in life, and in my choice of a role, I don't choose somebody by going 'Do I morally agree with them or not?' Do I sympathise with somebody is irrelevant to me; but the word empathise, do I understand them? Kenny is a pure spirit, and I understand him. I'm not here to judge if he's right or wrong. But man, he's a life force."

Much the same could be said about the latter-day Matthew McConaughey. For a stretch there, during his rom-com period, his name became something of a punchline. But these days, McConaughey is well and truly in on the joke. Hell, he's the one telling it.

At the peak of McConaughey's renewed fame and respect, he did a series of ads for the Lincoln Motor Company. Maybe there was a happy synergy in the fact that The Lincoln Lawyer (2011) kicked off what has come to be known as "the McConnaissance", but at any rate he took to his role as salesman in chief with gusto.

"I've been driving a Lincoln since / Long before anybody paid me to drive one," he said, his idiosyncratic phrasing lending an air of deep sincerity to the copy. "I didn't do it to be cool. I / Didn't do it to make a statement. // I just liked it."

In another spot he purred: "Sometimes you've gotta go back / to actually move forward. / And I don't mean going back to reminisce or chase ghosts. / I mean going back to / see where you came from. / Where you've been, how you got here. / See where you're going. // I know there are those that say you can't go back. / Yes you can. / You just have to look in the right place."

As cod philosophy it's easy to mock – as Jim Carrey did on Saturday Night Live – but it furthered the mystique.

More recently, he's signed on not just to help sell Wild Turkey Kentucky Bourbon, but to help shape how it's sold.

"I want to be more than just the face in the campaign," he said in a promotional film released last year. "I want to have my hands in the clay of how we tell the story. I want to be part of the whole story, and not just a character in it."

Of the bourbon itself, he added: "We're not going to be for everybody, and that's OK. If we're for you, you'll know."

The New York Times called this schtick the Tao of Matthew McConaughey, a guy-focused spiritualism of which he is the chief guru, and whose central tenets can be summed up thus: "Listen to your own inner tune. Go where it takes you. The good things you discover along the way, you were meant to discover. Tomorrow's hangover? You were meant to have that, too."

All of which suggests McConaughey hovers somewhere slightly above the stressed-out realm occupied by the rest of us, a benign demigod with perfect abs sitting in the lotus position on a magic carpet, eyes twinkling at the petty preoccupations of us mere mortals below.

So it comes as welcome relief to hear that he does occasionally concern himself with more worldly things.

In the long period between first reading the screenplay for Gold and actually making it, he says, there were many moments when it looked like it might not ever get made, and that stressed him out. Directors came and went – Spike Lee, Michael Mann – before Stephen Gaghan, who wrote Traffic and directed Syriana, landed on it. For a while, too, it was Christian Bale who looked most likely to play Kenny Wells.

"I was losing sleep because I thought I'd lost it," he says. "But luckily it came back to me."

He signed up for the animated movies Kubo and the Two Strings and Sing, he says, because he was growing tired of having to say "none" every time he was asked which of his films his three young children most liked. "So I said, 'Let's go do some stuff the kids can see'."

Buster Moon, the musical theatre impresario koala of Sing. Photo: Universal

It's tempting to see some symmetry in the fact he plays a koala in Sing: after all, he spent a year in Australia as an exchange student when he was 18. But, he says, for all that he saw a lot of koalas, their inner essence remained a mystery to him.

"It wasn't like I picked up all my koala traits," he says. "I didn't come away going, 'I know the personality of the koala'."

But I'm not so sure. Sleepy-eyed, chilled, hanging above us all – and barely a shirt in sight? That kind of reminds me of someone.

Sing is out now. Gold opens on February 2

Karl Quinn is on facebook at karlquinnjournalist and on twitter @karlkwin