"I've been out in the desert with my head, literally, in the sand for months," he says. "I feel a little bit lost when a film wraps."
But there's no time for Hoult to wallow: 2013 will be a big year for him, the one in which the 23-year-old graduates as a leading man.
Coming up is Warm Bodies, a zombie/romantic comedy genre mash-up co-starring John Malkovich and young Australian actor Teresa Palmer. Hoult plays R, a morally conflicted zombie who wanders across the United States eating human brains and "getting high on his victim's memories", as Hoult explains it.
Until, that is, he meets and falls in love with Julie (Palmer), an event that could just reverse the apocalypse.
It's a performance with great comic timing, and Hoult is enthusiastic about the film, but seems aware that viewers will either love it or hate it.
"It was an interesting part to take," he says. "I thought it wasn't playing into stereotypical roles that young actors can get trapped doing. Some people that have enjoyed what I've done previously may not like it, but that's okay."
First, though, he's the lead role in Jack the Giant Slayer, a monster-budget Hollywood number based on the beanstalk fairy tale.
Does he feels at all nervous that he's now carrying a major Hollywood film?
He thinks for a moment before responding: "The lead actor, along with the director, plays a big role in what the vibe will be on set, and that's a huge responsibility. But, yeah, I feel ready."
It's taken 10 years to transform Hoult from child star to big-time Hollywood player. He made his professional debut, aged 7, in 1996's Intimate Relations, starring Rupert Graves and Julie Walters, before his breakthrough role, at the age of 12, as Marcus Brewer in 2002's About A Boy with Hugh Grant. He's been famous for a long time: did the attention have an effect on him?
"A little bit, but I was very distant from it at the same time," he replies. "There was quite a gap between About A Boy and my role in Skins, and that was important for me. I needed to decide that acting was what I really wanted to do. A lot of child actors keep acting for the wrong reasons."
His performance as the sly and manipulative Tony Stonem in the teen drama, which marked his return, was a triumph. Then, three years ago, his big break came along. Tom Ford cast him in his directorial debut, A Single Man, opposite Colin Firth.
At the time, Hoult described the experience as "very cool" and today he says that he only hopes that he can one day emulate Firth and Ford's "grace and natural charm - it makes everyone else's job easier".
By comparison, he describes himself as having an "obsessive" nature. What does he mean?
He explains that he quite often "goes through phases with things, like when I was on the set of Mad Max, I learned how to knit and threw myself into it wholeheartedly. I knitted 24/7, pretty much. It got to the point where it wasn't fun any more."
His parents used to call him "Toad", after the character in The Wind in the Willows, because "he'd pick up an idea and run with it, and then suddenly drop it and move on to the next thing".
"When I like something, I love it, but then I'll let it go completely."
Hoult certainly has the air of someone who is highly strung. He says he "operates best on a bit of nervous energy".
He then goes on to apologise for being a bit "edgy" and explains that he hasn't slept for three days.
At one point, he narrows his eyes and asks me whether I've ever considered wearing a wire instead of using a dictaphone, then stops himself: "Sorry. That was a really inappropriate thing to say."
Even the word "famous" is making him flinch and fidget. This may be a bit of an issue, as it will be hard to escape him over the next couple of years.
Already, the tabloids have made a meal of his two-year relationship with the Oscar-winning actor Jennifer Lawrence, who he met on the set of X-Men: First Class. How has he found the paparazzi attention?
"The paparazzi don't care about me," he says with a grin.
Actually they do: I saw some recent pictures of him and Jennifer in a carpark. "It's weird, most of the time you don't even see them. They're like ninjas."
I take the opportunity to ask how Jennifer is, but all he'll say is that they are "doing well" and he promptly shuts down, which is fair enough.
Some weeks after we meet, there are reports that the two have broken up, followed by rumours that he'd taken up with his Warm Bodies co-star, Teresa Palmer. There's also the added complication that he and Lawrence will be reunited for the next instalment of X-Men, due to start filming in the summer. It's the type of attention you sense he'll hate.
Hoult is intriguing, a refreshingly raw talent in an industry that tends to homogenise and tightly control its young. He's at a point in his career that he says "could go either way, depending on how these two films go" - but I'm inclined to disagree.
The level of success coming his way seems in direct proportion to his fierce work ethic.
"I like to keep busy, otherwise my brain starts ticking and I will go mad," he says.
He gets up to go and meet his sister, pulling up the hood on his parka before leaving me with one more thought: "It's not healthy to be idle. There shouldn't be time to sit around and feel sorry for yourself and think too much.
"Long-term boredom can't lead to anything good."
Who: Nicholas Hoult, the former boy in About A Boy.
What: Jack the Giant Slayer opens March 23; Warm Bodies opens April 11
- TimeOut / Observer
