Actor. Eco-warrior. Activist. It's an impressive list. She's just not sure she's a feminist. "I am not great with labels. I am not a person who likes to put labels on anyone," she says. "But in terms of what you can have and what you can't have, it's all relative. So, what are we fighting for? What do we want more of? If we are fighting to have what men have, is that really what we want?"
Let's start with the basics. "There are certain things we should all have: male, female, straight, gay, whatever ethnicity. Basic civil rights we should all have, absolutely. And we should never stop fighting for that," she says. "But representation in film? [That's] not life or death. We can still live those stories, we can still keep building our own understanding of women and our relationships, and can still, in life, be engaged by those things and not see it on the screen for it to proliferate.
"There are certain things I'd concentrate on, as a human being, rather than a feminist. As a woman, I am not looking to have all the things men have. As human beings, we should all have what we all deserve. I will always fight for that. But whether I feel women are under-represented ... I feel there are a lot of ways I can spread that message, and a lot of ways I can be engaged to help people understand that it's something I think is important."
So, not a feminist, perhaps, but a great and passionate believer in the sisterhood. The Other Woman may be the latest in a long line of girl power movies, but it seems to echo most loudly with 1980's Nine to Five and 1996's The First Wives Club.
At the mention of Nine to Five, one of the most successful films in Hollywood history, Diaz's eyes dazzle. "Yes! I love it," she enthuses. Nine to Five's revenge story (on the "sexist, egotistical, lying, hypocritical bigot" boss) was central. But the enduring appeal of the film is the unlikely friendship of a working mother, an awkward divorcee, and a big-busted country girl, and Lily Tomlin's, Jane Fonda's and Dolly Parton's luminous portrayals of the three as each discovers there is more to the other two than meets the eye.
"Women are taught that we're supposed to be pitted against one another," says Diaz. "I never grew up that way. I was not drawn to women who were competitive with me. Any time I did, I found myself broken-hearted. [So] I just decided that as soon as I felt that from another woman, I'd go the opposite way.
"We live in a society where women are self-sufficient, they can take care of themselves, and what they need are more women in their lives. We understand each other, we know each other, we can be compassionate towards one another, the same way guys are 'bros' and 'buddies' together."
Those male relationships, Diaz notes, are celebrated culturally in the form of "buddy movies", the notion of gladiators, even the public-relations narrative of the armed forces. "With women, that is lacking," she says. We don't get to see how women can support one another and be there for one another." Yet Hollywood has an uneasy relationship with big chick flicks. Despite years of pressure for sequels to Nine to Five, Thelma & Louise and First Wives Club, nothing has come of it.
Diaz is matter-of-fact about Hollywood's appetite for female stories. "With everything, it comes as it's desired. We're seeing a new generation of women who are comfortable with asking for what they want, and the more women ask for that, and [the more] they know what they want, they will start to get it. It's also showing them things: 'Look at this'; 'This can be me'; 'I want to see more of that'. I completely relate to that. It's just a matter of presenting it to them and letting them know they can have it."
For Diaz, "having it all" seems relatively effortless, though she has to do so under the microscope of a modern media that now includes paparazzi and a billion-dollar online celebrity gossip industry. She is extremely guarded about her private life, but has been in high-profile relationships with Justin Timberlake, Alex Rodriguez and Jared Leto. Professionally speaking, The Other Woman is her 40th film in 20 years, with two more due out this year – the comedy Sex Tape, in which she co-stars with Jack Black and Jason Segel, and the film adaptation of the musical Annie, in which she plays the cruel Miss Hannigan.
Having a real life in the slightly unreal fishbowl of fame is not difficult, she says. "It's all about who you bring into your life. There's plenty of [false affection] out there. And I could be engaged with that if I wanted to. But I am just not drawn to that, I am drawn to authenticity and real people. I can sniff fakers out real quick and I have always been able to do that. In the past, whether or not they stayed in my life because I allowed them to, or for my own purposes, is one thing or another, but at this point in my life I am not interested in that and it's not something I have to worry about."
It's also a life lived in the space between the private and the public. Neither world, she says, is a happier space than the other. "Every film I have done, the process of doing it, from beginning to end, is unique, and that's what I love about the job that I do," she says. "So it's not about me, per se. I just try to be as engaged in the moment I am in."