Jennifer Aniston bares all in We're The Millers

It's appropriate that for her new film We're the Millers Jennifer Aniston's character assumes the fake identity of a mother, since it has long seemed that she has inhabited two personas. First there's the actress Jennifer Aniston, renowned for being the girl next door on the TV sitcom phenomenon Friends, who graduated to a leading lady in a litany of romantic comedies that have been greeted with mixed fortunes at the box office.

Then there's Aniston the tabloid queen. The one whose personal life has been the stuff of perpetual speculative soap opera since she split up from her husband Brad Pitt in 2005, and who is currently engaged to writer-actor Justin Theroux. This version of Jennifer Aniston has reinforced her position as one of the most recognisable stars on the planet and been a boon to the struggling magazine industry (her Marie Claire cover, for instance, in which she appeared in a tuxedo jacket was their top seller of 2011; ditto for US GQ's cover in 2009 in which she was pictured wearing only a tie.)

Sometimes the two Anistons converge. At the New York premiere of We're the Millers two days before I meet Aniston, 44, at a hotel in downtown Manhattan, erroneous pregnancy rumours were once again sparked by Aniston's supposedly rounder figure. The day after the interview, a picture of Aniston without her make-up that appeared on Instagram provoked hysteria among the blogosphere.

Aniston radiates calmness in person, acting as though she's oblivious to the fuss that surrounds her but wary of saying anything that would start a fresh bonfire of inanity. It's now exactly a year since Aniston became engaged to Theroux, the actor-writer nephew of esteemed travel author Paul Theroux, and tabloids are fixated on theories as to why the wedding has been delayed/postponed/dissolved. Questions about Theroux are off-limits for our interview (although she recently told E! News: “We have yet to set any dates. There have been no cancelled weddings. There have been no postponed weddings. There have been no arguments about where to get married.”

Yet We're The Millers, a sly, sprawling comedy about a deadbeat drug-pusher (played by comedian Jason Sudeikis) who joins Aniston's stripper Rose and two youngsters (Emma Roberts and Will Poulter) who pose as a fake family to drive a camper van to Mexico and profit from shipping marijuana back into America, will hardly diminish Aniston's allure in the eyes of the tabloids that she claims to find tiresome. This is largely owing to a raunchy scene in which Aniston's stripper character Rose performs an elaborate near-naked lap dance to a villainous drug lord to the sound of Aerosmith's Sweet Emotion (Aniston herself chose the song –“Steven Tyler [Aerosmith's frontman] sang to me on my birthday once”).

It's an even more revealing movie moment since Aniston has avoided such edgy terrain and also because Hollywood usually opts to have someone half her age to film those kind of scenes. Aniston says no research was necessary owing to her own youthful exploits. “I've been to enough strip clubs in my twenties as a fan,” she admits. “I had an incredible choreographer, Denise Faye, who taught me this beautiful dance and we just perfected it over weeks and weeks.”

But when it came to actually shooting the sequence she was overcome with nerves. “It was the first time walking onto the set with the crew and cameras and having to do the dance,” she says. “It was a little challenging and I was very intimidated. But you've got to go to work. The show must go on!” What was she thinking while in a state of undress? “Don't f**k up because you'll have to just do again and, it honestly was [about trying] to get up the steps without looking like you're suffering and removing your shirt at the same time.” Aniston, the face of Smart Water, jokingly throws a namecheck in to the brand she represents: “The water [that engulfs her during the routine] was very refreshing... There was a big Smart Water truck outside!”

Aniston insists the part of a curvaceous pole-dancer took an extreme physical toll. “I actually did go to a very scary gym with a scary trainer who made me do crazy things that I can't say out loud,” she says. “I got real strict with my diet and I was very persistent with my work-outs. When I finished that job I pretty much didn't go to the gym for I don't know how many months. I was over it and like, 'OK, that's enough of that!”

The reception for We're the Millers' subversive take on the notion of American family has been positive by the standards of what has so far been an underwhelming summer for Hollywood blockbusters. “It's a very original idea, funny beyond words,” Aniston says of the film. The Hollywood showbusiness trade publication Variety drily noted of its New York premiere: “The crowd that filled the Bryant Park Grill following the screening of We're the Millers seemed happily surprised with this original summer entry.”

It's fair to say critics haven't been happily surprised with much of Aniston's cinematic work. A decade as Rachel Green in Friends made her name – and $1m an episode – but Aniston capitalised on her TV fame by starring in a mixed bag of romantic comedies including 1998's The Object of My Affection with Paul Rudd and Nigel Hawthorne, directed by the National Theatre's outgoing Artistic Director Nicholas Hytner. (One can only wonder what the result would have been had Aniston pursued a career in theatre, like her Friends co-star David Schwimmer, and re-teamed with Hytner for a stint at the South Bank).

For all its considerable success, Friends placed its six stars in something of a creative straitjacket. There's even an allusion to this during the end credits of We're The Millers that shows outtakes from the film. One shows Aniston being pranked by her fellow cast members who sing along in a camper van to “I'll Be There for You” by The Rembrandts, the theme song of Friends, instead of to TLC's “Waterfall” as scripted in the film.

A more experimental detour a decade ago into independent movies and thrillers (Derailed, The Good Girl, Friends with Money) didn't last long and Aniston soon returned to rom-coms, some of which worked (The Break-Up) and some of which didn't (The Bounty Hunter, Just Go with It). Aniston's reservations about Hollywood saving the great comedy roles for men are well-established, so why is she continually drawn to comedy? “I love making people laugh,” she replies. “It's something I enjoy immensely. Comedies are something more fun. But I've also just completed a dramatic piece, Life of Crime [an adaptation of Elmore Leonard's 1978 novel The Switch]. It's what parts come to me. I tend to gravitate towards comedies because they feel good.”

I ask her if another reason for this might be that comedies make it easier for her to laugh at the shrill tabloid version of her life that prevails. She insists not. “As for the tabloid life, I just try to do my job and do it well and drown that stupid noise.” Much of the noise has revolved around motherhood. In a notorious 2005 Vanity Fair interview conducted shortly after the public implosion of her marriage to Brad Pitt and his ensuing relationship with Angelina Jolie, she was definitive about the subject, saying “I've always wanted to have children.”

Now when asked about the prospect of having a family, Aniston adopts a more cautious line, hinting that her childhood has already resulted in her assuming parental responsibilities. “I feel like a mother to a lot of my girlfriends,” she says. “My girlfriends and I are all very maternal. We are each other's mothers, sisters, girlfriends, everything. Because a lot of us had not the most fabulous parental experiences in our own lives, we learnt our own parental techniques and we took care. We family each other and so it's an instinct I've had for many, many years.”

Intriguingly Rawson Marshall Thurber, the director of We're the Millers, tells me Aniston reminds him of Sienna Miller, whom he directed in his previous film, an ill-fated adaptation of Michael Chabon's 1988 literary novel The Mysteries of Pittsburgh that remains unreleased in the UK. “They're both beautiful women, talented and really funny,” he says. “Jen's funny on film – Sienna doesn't do comedy, but she's really funny in conversation – and they're incredibly down to earth. For lack of a better term they're both 'one of the guys'.”

We're The Millers was partly shot in Santa Fe, New Mexico, but not actually in Mexico itself, where Aniston regularly likes to holiday. She is often pictured by the paparazzi on holiday in the tropical resort of Cabo San Lucas, located at the southern tip of the Baja California peninsula, with friends who have included Emily Blunt and US chat show host Chelsea Handler. “I love going to Mexico because it's close and because the people are so kind and have a wonderful work ethic,” she says. “You're treated so well. And who doesn't love Mexican food?”

Marshall Thurber, a dead ringer for former Arsenal footballer Dennis Bergkamp, reckons Aniston copes admirably with the circus that surrounds her. “I really wasn't aware of how prevalent it was in her life until we started working on this film,” he says. “It just seems to me such a difficult way to live your life to always be photographed and be hounded and asked questions constantly. She handles it all with aplomb.” He adds Aniston doesn't always get her comedic dues: “Friends is Hall of Fame comedy but on the film side she's great in one of my all-time films, Office Space, and she stole the show in Horrible Bosses.” In the 2011 comedy Horrible Bosses, Aniston played a nymphomaniac dentist alongside Jason Sudeikis with whom she also acted in The Bounty Hunter. Unlike Gerard Butler and Vince Vaughn, he has never been romantically linked to Aniston but the two have an obvious rapport. “We're a package!” she jokes, adding they will re-team to film a sequel to Horrible Bosses. Proving that old habits die hard, Aniston has just finished shooting another romantic comedy, Peter Bogdanovich's Squirrel to the Nuts, in which she plays a therapist alongside Owen Wilson and Rhys Ifans.

But a UK romantic comedy that Aniston was announced last year to be starring in, Miss You Already, directed by Paul Andrew Williams (Song for Marion), has been put on the back-burner. Toni Collette had been lined up to co-star alongside Aniston but the project is now on hold. Williams is now preparing to direct a war drama with Tom Hiddleston and Hayley Atwell and Aniston will not be filming in London this year as scheduled. Aniston's UK fans will have to contend with red-carpet appearances and the inevitable media sideshow that her impending marriage to Theroux will generate. The interview over, I spot Aniston entering a lift with her We're the Millers co-star Emma Roberts and a sizeable security entourage, only for her bodyguards to deem there are too many civilians inside the lift. They scurry out in a hurry to the adjacent lift as though it was a ship that was sinking and not an elevator that was ascending. It is an amusing scene and though Aniston and Roberts appear vaguely alarmed by the minor panic that ensues, I hope that in light of her penchant for screwball comedy, on reflection Aniston can see the funny side of such encounters.

'We're the Millers' is released in the UK on 23 August