TELEGRAPH – When I meet Shailene Woodley, she’s holding a cup of something mud-coloured and healthy-looking. In an attempt to establish some common ground. I hazard a guess: green tea? It turns out to be nettle. “It gives energy, and is full of iron,” she tells me. “So it’s especially good if you’re menstruating.”

I quickly learn that it’s a pretty typical Woodley comment – she channels a sort of hippy-ish, California vibe (she grew up just outside LA, she’s passionate about environmentalism, she drinks nettles), that sits alongside some very genuine down-to Earth charm.

If anyone’s in need of energy-boosting beverages, it’s Woodley. The actress had three films open in 2014: dystopian thriller Divergent (a sequel, The Divergent Series: Insurgent, is out next year), dark indie drama White Bird in A Blizzard, and bittersweet teen tearjerker The Fault in Our Stars.

The latter, adapted from the John Green YA novel, tells the story of a romance between Gus and Hazel, two teenagers with cancer. Even if you haven’t actually read The Fault in Our Stars, you’ve likely read part of it. Pithy, bite-sized quotes from the book – “As he read, I fell in love the way you fall asleep: slowly, and then all at once”; “Some infinities are bigger than other infinities” – have invaded social media, testament to the novel’s popularity with its intended audience.

Despite its difficult subject matter, the film was was a breakout hit, grossing $304 million worldwide against its relatively modest budget of $12 million, and, along with Divergent, propelling Woodley to household name status. Previously, the actress made her feature film debut in Alexander Payne’s 2011 film The Descendents, playing the elder daughter of George Clooney’s character; prior to that she starred in the ABC Family series The Secret Life of the American Teenager. She was offered the role of Mary Jane Watson in The Amazing Spider-Man 2, but her part was cut from the film, after the filmmakers made the decision to focus on the relationship between Peter and Gwen.

Woodley’s performance in The Faults in our Stars drew critical acclaim – as Hazel, she’s funny, vulnerable, acerbic and heart-breaking all at once – but, perhaps more importantly, earned a seal of approval from the book’s dedicated army of young fans.

“I felt pressure from myself, not from any outside source,” she says, when I ask if it was difficult taking on something with such a hardcore fan base. “Just because the book, and the screenplay, affected me on such a cellular level.”

In fact, Woodley, who read Green’s novel immediately after finishing the script, wholeheartedly includes herself among this fan base. At 23, she’s pretty much slap bang in the middle of Green’s target audience. But her enthusiasm and lack of cynicism are refreshing.

“I’ve never read a script where I laughed out loud as much as I did when I read it,” she says. “I felt, if I do this movie, it won’t be for me as an artist… it will be me, literally protecting the integrity of John Green’s original thoughts.”

Back in April, Woodley told Marie Claire “I just haven’t met anyone where I was like, ‘Wow, I could definitely see myself spending a season of my life with you'”. In the past year, the press have linked her to everyone from her Divergent co-star Theo James to, more recently, indie musician Nahko Bear. Questions about Woodley’s private life are, understandably, off limits. But she’s happy to talk about relationships in a wider sense, explaining how important it is that she’s maintained her pre-fame friendships, along with forging newer ones. “I have friends who are newer: actors and directors, that I’ve met through this industry, “ she says. “Wherever you go, you find your tribe.”

In The Fault In Our Stars, Woodley’s love interest Gus is played by Ansel Elgort, who also acted alongside Woodley in the first instalment of the Divergent series. In the latter film, he plays Woodley’s brother; was that a difficult transition to make?

“No,” she says. “It was really nice, actually. Ansel and I are actually incredibly close, and have a very brother-sister like dynamic in our personal lives. I definitely think that, if you’re going to be intimate with someone on screen, that you need to be comfortable with that, with them”.

The love scenes in The Fault In Our Stars are tender in a recognisably teenagerish, first love kind of way, but Woodley embraced a more adult side in Gregg Araki’s White Bird in a Blizzard. In the film, she plays adolescent Kat, who explores her sexuality with a classmate, and seduces the police officer investigating her mother’s disappearance.

“I didn’t find it a challenge. I knew what I was signing up for,” she says, when I ask how it felt to film her first nude scene. “Sex is a very natural part of our lives as human beings. I think very rarely do we see adolescence experience or sexual encounters in a very grounded way. And so I thought it was really neat actually – to be part of a project that wasn’t afraid to explore the other side of coming of age stories.”

Woodley’s professionalism and grounded attitude have drawn praise, but she has her detractors. The two main accusations levelled at the star are that she’s “anti-feminist”, and that she’s some kind of “crazy eco-warrior”. She attracted controversy earlier this year after an interview with Time Magazine, during which she stated: “I love men, and I think the idea of ‘raise women to power, take the men away from the power’ is never going to work out because you need balance.” Later, in an interview with EW, Woodley claimed that, while she prefers to think in terms of “sisterhood” rather than feminism, her comments had been misrepresented by the journalist.

While the ins and outs of her remarks are still being debated in numerous internet blogs – and it’s a dialogue that’s worth having – , something that struck me at the time was how intensely we demand perfection from our stars, in terms of attitudes, as well as looks. Certain sections of the press were quick to deride Woodley as a “bad role model”. But does Woodley actually want to be a role model? Does she feel pressure to behave a certain way, given her (predominantly young, female) fan base? “I feel like, if I lived my life for anyone else, I would be missing a lot of self nourishment, and a lot of self love,” she says. “So I just try to lead a life for myself in the best possible way.”

As for the second charge – that of being an “eco-warrior”– it’s one I suspect Woodley would warmly embrace. She famously doesn’t own a mobile phone, makes her own herbal medicines and prefers to wears used clothes: it’s a lifetsyle that easily attracts scepticism, if not ridicule. But when she speaks about her environmentalism, she’s impassioned and palpably sincere.

I’m definitely really passionate about the environment,” she says. “I think it’s important to recognise that we’re all indigenous creatures on this planet. We all come from the Earth and we all go back to the Earth.”

She says she tries to eat as organically and naturally as possibly (which explains the nettle tea), foraging and growing her own food where possible. On a shallow note, whatever she’s doing is clearly working: Woodley glows in a way that seems rather incongruous on a rainy afternoon in London. But for her, it’s about the planet, rather than just personal wellbeing. “Eating organic food, and whatnot, and eating healthy, makes my body feel better. But I don’t eat organic food for myself,” she explains. That said, Woodley sees her lifestyle as a “fun challenge”, rather than an onerous obligation. “Life is a game, you’ve got to have fun with it. If you take anything too seriously, you’re just creating stress and worry, and guilt that does not need to exist.”