Jonah Hill – star of Superbad, 21 Jump Street and Moneyball – has always wanted to work with Martin Scorsese. Now he's got his wish. He talks to Hermione Hoby about losing weight, giving up comedy and making Leonardo DiCaprio sickNews: The Wolf of Wall Street criticised for 'glorifying psychopathic behaviour'

A couple of years ago, in the Beverly Hills Four Seasons hotel, Jonah Hill walked into my lift. Flanked by four attentive young women, he was recounting a series of travails involving his interior designer's work on his new apartment – he had, as I remember, a spot of bother with the pronunciation of "aesthetic". He was on the brink of becoming a big star. Our brief encounter chimed perfectly with his first Oscar nomination for 2011's Moneyball, which was as spectacular as a movie about baseball statistics sounds. It was Hill's performance as Peter Brand, a Yale economics wünderkid, that stood out. Here was the schlubby funny guy from Superbad giving a masterclass in reserve, his small thoughtful features lost in the big moon of his face.

In interviews around that time Hill seemed preoccupied with his own actorly apotheosis, his eagerness to be hailed a "serious actor" so egregious Buzzfeed ran an article rounding up the "6 Quotes That Show How Jonah Hill May Have Turned into a Pompous Jerk". Among them: "I could have made a billion dollars doing every big comedy of the last 10 years and didn't, in order to form a whole other life for myself." To accompany his transition to Hollywood heavyweight, he also shifted a reported 40lb in weight, a "sign of maturity", he said. "I think you are taken [more] seriously." But perhaps Hill was falling victim to his own ego. Overhearing him lamenting the shortcomings of his interior designer in the lift certainly felt like watching the Saturday Night Live parody of him.

Today, as I wait to meet him in a suite at New York's Mandarin Oriental hotel, that same sensation of Hollywood absurdity returns. This time, four women and their smartphones are embroiled in a crisis involving their charge's mislaid shoes. Beyond the door I envisage a red-faced tyrant, but Hill's grinning, texting on his phone when we're introduced.

"Hi!" he says warmly, looking up. "Sorry, my friend was just sending me a picture of his dog! I love dogs! I'm texting back: 'I want to squeeze him.'"

I tell him there's quite a drama going on outside involving his footwear. "Oh really?" he says, delighted. He points down to a pair of plasticky Nike slip-ons that he's wearing with an expensive-looking charcoal-grey suit. His chauffeur, it turns out, has failed to deliver the real shoes. It would be no problem, except he's attending the premiere of his latest film that evening, and it's a film directed by Martin Scorsese, Hill's "number-one idol".

Being cast in The Wolf of Wall Street, Scorsese's biopic about Jordan Belfort, the New York stockbroker multimillionaire played by Leonardo DiCaprio, has evidently been nothing short of a dream. "[People] can diss me all they want on a blog or in a magazine and I'll just be like: 'Whatever, man. Scorsese thinks I'm awesome,'" Hill recently told an American journalist. He tells me he was terrified of jinxing his audition for Donnie, the orthodontically challenged, pastel-shirted degenerate who becomes Belfort's sidekick after meeting him in a diner, so he didn't tell anyone. It's a sterling part, with Donnie being drawn into a life of excess and greed, and in many ways it's Hill's film, despite the actor taking on another supporting role (Moneyball paired him with Brad Pitt and 21 Jump Street with Channing Tatum). "Donnie's very entertaining," says Hill, "because there's no impulse control, no morality at all. He does whatever he feels like that second without considering anyone else. He's just pretty vile."

The film itself has a similar feel: relentlessly entertaining but brazenly, outrageously amoral. I tell him watching it felt a bit like eating a whole chocolate cake; delicious at first, but you soon start to feel sick. Hill nods. "We had orgy scenes and shooting those was pretty repulsive – naked people in a confined space for 18 hours a day. It was not sexy at all."

And then there were the avalanches of "cocaine" – vitamin D powder hoovered up by Hill and DiCaprio line after cigar-fat line in every scene. "I snorted so much of that stuff that I got, like, bronchitis!" Hill laughs. "My lungs were filled with powder and I got really sick for a month and a half. But, I mean, I'd do it again in a second. The first time you snort fake cocaine in a Scorsese movie you feel like… I don't know!" He winces. "I got embarrassed because I said that it's every actor's dream. I guess it's not, but to me, it's a pretty iconic thing to do. "

Jonah Hill with Michael Cera in 2007's Superbad. Photograph: Allstar

There's a moment where he lurches in slow motion around DiCaprio's shoulder at a pool table, quaaluded to the point of collapse. "And it's just so cool-looking!" he pants. "Scorsese's the person who does that better than anyone in the world. I was so excited to get to be shot, in slo-mo, doing drugs in one of his movies."

He talks fondly of DiCaprio "physically tormenting" him in many of their fight scenes. But Hill got his own back. In a scene where their characters share a sushi lunch, Hill is scripted to eat the last piece of sushi. "He has to ask whether I'm going to eat the last piece," says Hill. "But instead of saying my scripted yes, I decided to say no. And I kept saying no," he laughs, to the point where they did take after take and DiCaprio was forced to keep eating until he genuinely threw up. "It's so unfortunate that's what makes me happy," Hill says. "I guess that's my little speckle of Donnie."

If there's a speckle of Donnie, it's hard to see it beneath the nice young Jewish boy who took his mother as his date to the Oscars. This is Sharon Lyn, a costume designer, married to Richard Feldstein, a tour accountant for acts like Madonna and Guns N' Roses. Hill is their middle child; he has a younger sister and an elder brother, Jordan Feldstein, manager to Maroon 5 and Robin Thicke.

Hill grew up in LA, but it was New York that afforded him his first break. While studying at Bard College he'd put on small plays in a Manhattan dive bar and it was through these that he befriended Dustin Hoffman's kids. He then so impressed their dad with prank calls and improvised comedy that Hoffman engineered an audition for I ♥ Huckabees, the 2004 David O Russell film. Hill got the role but didn't work again for three years. He'd audition for TV sitcoms, but "I would always get in trouble because I would rewrite all their material because it wasn't very good. I was 18 and I was like: 'Oh, they're going to be so happy – I'm making their material better!'"

With Brad Pitt in Moneyball.

Then in 2007 Judd Apatow cast him in Superbad as a hornily deranged teenager alongside a meek Michael Cera, and everything changed. He recalls coming out of his tiny LA apartment, bleary from playing video games, and looking up to see an enormous billboard with his face on it. He owes everything, he insists – the Oscar nomination, getting cast by Scorsese – to Apatow and Seth Rogen: "They are and were so amazing to me."

I ask him about the Oscars ceremony. Who had more fun, him or his mother?

"She did!" he shouts. "She was sitting next to Brad Pitt's mom; she was having the time of her life. Owen Wilson's mom and her were talking all night! All the moms were there. It was a big thing, the moms. I love having her around."

So much so that he even invited her on set for True Story, a drama out later this year based on the real-life relationship between the journalist Michael Finkel, played by Hill, and Christian Longo, an FBI most-wanted murderer played by James Franco. The film was shot out in the snow in a harsh New York winter and was, he says, "honestly depressing". "So I was like: 'Hey Mom, do you want to come hang out for a few months so we can enjoy this time? I miss my family so much.'"

True Story will be Hill's 30th film, but despite the credits and accolades, the third most popular Google search word for Hill remains "weight". Today he's not the rotund of Superbad nor quite the skinny of post- Moneyball; he looks tall and broad-chested, well-groomed, with close-cropped hair.

Taking direction from Martin Scorsese on location for The Wolf of Wall Street. Photograph: WireImage

Did he feel it was important to step away from comedy? "It's not like I don't like comedy and don't like making people laugh – I truly enjoy it. But I realised once I got success in that world, it was… well, I love all different kinds of films. I love dramatic films as much as comedic films. And so when Superbad came out I made a really conscious effort not to star in another film until it was something that presented some sort of different challenge. The reason is, I won't get better if I just keep working on things I've done already."

Maybe, but it is the non-serious stuff he's loved for – more recently, the feckless overgrown kid of a cop in 21 Jump Street and the burlesque version of himself in This is the End, where, mid-apocalypse, he begins a prayer with this line: "Dear God, it's me, Jonah Hill… from Moneyball."

Not that God needed the reminder – Hill is now pretty much a household name.

"Is that true? In England?" he says, eyes popping happily.

Does he enjoy being famous?

"I never complain about any facet of celebrity or anything because it would be ridiculous to go be in movies and then complain that people know who you are, right? I don't really like being famous, it's not something I ever wanted, but I wouldn't trade being in movies for anything. And getting people knowing who you are and liking your films allows you to make films."

Jonah Hill and his mother at the 84th Annual Academy Awards in LA. Photograph: Rex Features

He recounts being at a urinal a year or so ago and having the guy next to him lean in, swing his arm round him and snap a selfie. "I'm like: there's no more vulnerable, private space! But I'll never complain. I just want to make movies that I want to go see. I'm the luckiest guy ever, because I would go see those movies opening night!"

I believe him. The way he enthuses about film is guileless, like a kid. He will, however, be celebrating his 30th birthday a few days after we meet. He jokes: "It's OK, my life's over, that's fine" but also says that turning 30 means feeling "a lot more confident about not doing things, you know? This is the first time ever that I've felt I'm not going to take a role unless it's something I'm really passionate about and it's really going to challenge me. When I decide to play a part, I care about it as much as anyone could care about anything. I started when I was really young and I was always the youngest person in the room. Now I just feel like I have a seat at the table in some way. Respectfully. You know?

"The goal was to work with Martin Scorsese, and I got to do it and that's all I wanted in my creative life. That was my dream."

• The Wolf of Wall Street opens on 17 January

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