What's new Pussycat? Nicole Sherzinger on being a global pop star and conquering an eating disorder

In an east London studio, Nicole Scherzinger is undergoing a process entirely common among pop stars but wholly inexplicable to the rest of us. Dressed only in a white towelling robe that she has rucked down to reveal naked shoulders and a lot of breastbone, she is sat before an overlit mirror while a make-up artist removes the make-up that was applied barely an hour earlier (for one photo shoot), only to then apply more (for the next).

There are, one has to presume, subtle but key differences to the make-up being applied now, but to the ignorant observer, one line of mascara – if, that is, mascara comes in "lines" at all – looks much like the other. She is also having her hair re-fluffed, primped and preened. It is a process that involves an awful lot of potentially ozone-depleting spray, much of which I swallow while attempting to hold a conversation with her.

Scherzinger is a naturally pretty 34-year-old who, that same ignorant observer might well suggest, hardly requires all this fuss and bother. She makes eye contact with me in the mirror now, and sighs with what seems like exaggerated weariness but which, on reflection, might not be exaggerated at all.

"You boys," she drawls, extending the elasticity of her American accent, "have no idea what's involved. No idea at all."

I suggest that she must find all this daily intensive preparation a terrible chore. This causes her to frown gravely, the worry lines on her forehead presenting immediate problems for the make-up artist, who would much rather work on a creaseless surface. "Oh no, not at all. It can feel a little stifling sometimes, perhaps, but mostly I have to look at all this as a blessing."

A blessing? Yes, she responds, a blessing. "All this" – the fame and success and, consequently, the excessive attention to prettifying detail – was her destiny. "It's what I always wanted. So I'm not going to sit here and complain about it, am I?"

In many ways, Nicole Scherzinger is perhaps the ultimate modern celebrity, someone who, at the risk of sounding like an estate agent, ticks all the right boxes. She is a globally famous singer, formerly of the burlesque Pussycat Dolls, now solo (and about to release a new single, "Boomerang"). She is the delectable arm candy of Formula One star Lewis Hamilton, with whom she is perpetually papped at hi-vis events. And she is televisual gold courtesy of her work on The X Factor, where she is not merely one of four judges, but last year's winning judge: 2012's victor, James Arthur, was hers. (So was Rylan Clark, so if anyone is to blame for his improbable ubiquity, it's her.)

But this isn't what's so interesting about her. What's interesting is that she has risen to such heady heights – or, as she would have it, "the mountaintop" – not necessarily through natural talent (though, of course, she possesses that), but rather tireless hard work and an unswerving focus. While she is a more-than-able pop star, she possesses neither Lady Gaga's edge, Katy Perry's chutzpah nor Rihanna's élan. She doesn't sing as well as Beyoncé, or boast the musicality of Alicia Keys. Her biggest hits possess the sense of efficient conformity which her go-to producer, Black Eyed Peas' Will.i.am, has conjured up for many of the artists he has worked with (most recently, Britney Spears and Cheryl Cole).

What sets Scherzinger apart, then, is drive, passion, unstinting commitment to succeed, to be the person she always dreamt she'd be. Everyone has ambition; she has more than most.

"Ambition? What's ambition?" she says disingenuously. I ask her what it means to her, and she answers like a child in class. "Um, someone who is really hungry?" And would she define herself as such? "I guess so. Definitely. I've always been like this, ever since I was young."

Born in Honolulu, Scherzinger is part Hawaiian, part Ukrainian. After her mother divorced and remarried a man of German extraction – whose surname Scherzinger kept – the family moved to Louisville, Kentucky, and lived a fairly blue-collar existence, she a clerk, he a welder. "No one else in my family was creative, a performer." So where did her inspiration come from? She smiles. "Maybe it was God's will? I just knew that it was going to happen. The moment I heard Whitney Houston sing, I realised that that was what I was going to do as well. I used to sign all my yearbooks in school: 'Remember me when I'm famous.'"

She excelled at school, but was not about to be waylaid by academia, and by her late teens she was the sometime vocalist in a band called Days of the New, and touring in earnest around the US. But by 2001, she had quit and enrolled instead on a prototype of American Idol called Popstars (the short-lived UK version produced the band Hear'Say). Recollecting Days of the New now, she is positively fawning: oh, they were brilliant, she says, and it was an honour to be a part of them. So why on earth, I ask, did she ditch them and seek instant stardom on television? Whitney Houston never did that.

She wrinkles her nose. "Because of my mom," she answers. "She saw a commercial on TV saying they were looking for the next new girl group, and insisted I audition. I said no, that I was in this great acoustic goth band, and I was also studying theatre and music at college. I wanted to be on Broadway. But she just kind of pushed me out the door anyway, and insisted I go. I'd been working on a solo package anyway, so I shopped it [to the show's producers]. I didn't have any money, so this was my way of getting to Los Angeles, I guess. The rest is history."

Televised history. The girl group she joined, Eden's Crush, won, but Scherzinger never saw this as a viable long-term option. Rather, it was a stepping stone. "I was still discovering who I was, and what kind of musician I was going to be," she says. Presumably, given her "acoustic goth" background, she found it difficult now to sing anodyne pop songs in a manufactured pop act? She shakes her head. "To be honest with you, I'm a performer, an entertainer. I was coming from that Broadway state of mind, theatre, and even though I write my own songs – I'm old school like that – I was still perfectly happy to take someone else's song and make it my own. See, all I ever really wanted to do was perform."

Within two years, she had left Eden's Crush, and was recruited into Pussycat Dolls, a pop act created by a record- company executive that aimed to combine burlesque titillation with catchy, commercial songs. "My first response when I was invited to join was, No way!" she admits. k "I come from a strong religious background, and I had a very conservative upbringing. So I was nervous, and confused. Here I was wanting to be Whitney Houston, so why did I have to dress in lingerie to do that? I didn't get it."

Her mother also had reservations. "She hated the name. She wanted us to be called, simply, The Dolls, and she prayed every night for it."

It never happened, but despite their shared worries, Scherzinger went along with it. "I didn't have a choice," she suggests. Nonsense, I say. Of course she had a choice. "OK, perhaps. But it was a heck of an opportunity."

She decided to overlook the overriding visual angle of the band, and concentrate on the music. Their first single, 2005's "Don't Cha" ("Don't cha wish your girlfriend was hot like me?") was a worldwide hit, and its follow-up, "Beep" ("I'm a' do my thing while you're playing with your… uh") ensured, to listeners at least, that the coquettish vamp act would always remain the main focus.

The demands of going to work in her bra and pants soon took its perhaps inescapable toll. From the very moment she became part of the group, Scherzinger was instructed to lose weight. That she didn't need to lose weight was immaterial, she says. "I simply did as I was told. You know, I didn't have the confidence to go around in all that lingerie. I'm a crazy bitch now, of course, and I'm all over that, I love it, I embrace it. But back then? Back then, I wasn't comfortable at all. I'd never worn stuff like that in my life."

Increasingly self-conscious about her body, she became bulimic. Her eating disorder lasted for more than a decade, but she has only recently decided to speak about it publicly. Tellingly, she still refers to it in the present tense as her "secret".

"As soon as I did open up about it [on a documentary for the music channel VH1], I regretted it. I felt humiliated, I didn't want it to be screened. I didn't want the world to see that side of me. But now I'm so glad they have. The impact I've had on other sufferers is just… I can't tell you, it's so amazing. That I am now in a position to give strength, and support, to others… It's awesome."

To help overcome her bulimia, she saw therapists and life coaches, but one thing she didn't do was take time out of the band that had so clearly exacerbated the condition. "I couldn't," she argues. "This job was something I was born to do; it was cast upon me. So I didn't have a choice to simply stop. I didn't."

Today, she is no longer bulimic. Confidence, she suggests, and maturity, are the reasons why. She certainly radiates confidence, and even in a skimpy bathrobe the woman exudes a kind of rarefied elegance one doesn't normally associate with modern pop stars. She has airs and graces, a natural sense of deportment. For example, she is clearly bored right now – she must be bored; it's been a long day – but she is never less than polite and courteous. She'd make for a great royal.

She says that it took years for her to come out of her shell, to feel comfortable in her own skin, and in the perpetual spotlight. Yet she is perfectly happy in her bra and pants these days, and you could say that she now almost aggressively courts an overly sexualised image. Conclusive proof of that came with her 2011 solo album Killer Love, which featured a duet with 50 Cent called "Right There" that dispensed with double entendres entirely in favour of blunt single ones. "I like the way that you keep me coming," she sang. "So good you had me running/ Me like the way that he goin' down down down down down uh."

Intriguingly, she delivered all this in so blatant a cod-Barbadian accent that it was difficult to tell whether she was aping Barbados-born Rihanna, one of her main competitors, or mocking her. Which was it?

"Well, um… you know." She laughs, the sliver of a giggle, then seamlessly changes tack. "With these kind of songs, I don't feel I have to justify myself to anyone. I come from the most religious family – my grandfather is a priest – and if they support me in all this, and they do, then I'm OK. I'm being sassy and classy; I'm having fun. I'm not coming from a dark place. To be honest with you, I sometimes wish I were more slutty. I'd probably be a lot more successful if I were."

For the past five years now, Scherzinger has dated Lewis Hamilton. It's been a long-distance relationship, she in Los Angeles, he in Monaco, and it has been endlessly raked over by the tabloids. The regal Scherzinger rarely comments on him, of course, though she did do the papers a favour last year by splitting up with him a while before reconciling. There is not a day that goes by now when she doesn't face questions about him: is she faithful, still in love, about to marry?

"I guess it means a lot of people don't have a life, because why else would they be so interested in mine?" she smiles. "You know, I try to avoid Googling myself, but sometimes I slip up. Sometimes I just want to see how the world is viewing me on a particular day."

And invariably its view is not an accurate one.

"I keep having to call up my parents to say, no, it's not true, none of it is, calm down." She frowns. "Why do people believe what they read? It's mostly lies."

If this sounds like a complaint, it isn't, not really. Scherzinger knows it goes with the territory, and she has long since accepted it as part of her life as the quintessential modern celebrity, and therefore, in its own skewed way, a kind of blessing.

She turns to face me now, forcing her make-up artist to take a step back.

"This is such a tough industry, you know. To make it, you really have to sell your soul to the devil."

And has she?

She turns back to face the mirror, and closes her eyes. Her make-up artist resumes her work. "No, I haven't. That's probably why I haven't quite reached the top of my mountain. I mean, where's my Tony Award, my Grammy, my Oscar? Why don't I have any of those things yet?"

Nicole Scherzinger's new single 'Boomerang' is released today. Her second album is released later this year