Lena Dunham is deconstructing femininity right across the table.

Having spiffed up for some behind-the-scenes featurettes for her upcoming HBO series, “Girls,” Dunham has relaxed into her seat at a Tribeca restaurant not far from where she grew up. Shortly after shedding her overcoat, she pulls off her fake eyelashes, too, apologizing for her manners and lamenting the forthright revelation of a women’s “secret” to a member of the opposite sex.

“There’s a certain point when I’ve had them on all day, I just want to be free of them,” she says. “I want to be naked but for my own lashes. It upsets your friends if you pull them out and just hand them to them. They’re not exactly sure what’s going on.”

Inhibition and a comical preference for naturalism run deep in Dunham and her work. She’s a self-declared “over-sharer” whose Twitter feed is a steady stream of self-deprecating wit. (“I was lying totally still on the shower floor and really hurt my knee. And that, my friends, is proof I can do anything.”)

Her work (two features, a few Web series and now the TV show) is heavily personal, like her breakout film, 2010’s “Tiny Furniture,” an indie she made for just $25,000 starring herself, her mother (the photographer and artist Laurie Simmons) and her younger sister, Grace. (Her father, the painter Carroll Dunham, typically abstains.)

“In many ways, my work acts as my journal,” she says. “When I had a journal as a kid, I was constantly leaving it open, hoping somebody would find it. I just didn’t understand the purpose.”

Not yet 26, Dunham has already been profiled by the New Yorker, had “Tiny Furniture” released on DVD by the esteemed Criterion Collection and attracted the interest of filmmaker Judd Apatow, executive producer of “Girls.” Considering her unblemished good fortune, Apatow has advised Dunham to get a T-shirt that reads “The Inevitable Backlash.”

“Girls,” which Dunham wrote, stars in and produced, premieres Sunday, but it’s already captured the zeitgeist, sparking a dialogue about 20-something adulthood, femininity and sexuality. The show follows four young women (Dunham, Allison Williams, Jemima Kirke and Zosia Mamet) in post-collegiate drift, struggling in a difficult New York job market, chafing at conventional ideas of womanhood and dealing with male counterparts on a different wavelength.

“It feels as though it’s the right time for this show,” she says. “Women want a show like this. This generation wants a show like this — not to overstate our mission.”

Dunham is the subject of op-eds (The New York Times) and the topic of considerable blogosphere debate. She’s been lauded for inverting the usual representations of female bodies by having no shyness in portraying her, as she terms it, “not exactly model-esque body” in unflattering sex scenes. But one critic suggested Dunham would lose her “narrative propellant” if she dropped 30 pounds.

“If I lost 30 pounds, I’d die,” she says. “Not to quibble with him about what overweight means, but I can’t even lose 30 pounds!”

Most, though, recognize in Dunham the genuine article: an uncommonly mature storyteller with natural instincts for autobiographical filmmaking and neurotic portraits of her self-absorbed 20-something generation. In a memorable scene in the first episode, Dunham’s character, having arrived in New York an aspiring writer, tells her visiting parents that she believes she’s the voice of her generation, “or a voice of a generation.”

It’s particularly fitting because it’s both true and a self-parody — a balance of sympathy and critique for Millennials that runs throughout “Girls.”

“That’s just always what’s made the world feel manageable is to be able to share my experiences with like-minded people,” she says. “And sometimes I end up sharing them with not like-minded people, too.”

Dunham grew up in a family of artists that moved from Soho to Brooklyn Heights (where Dunham is moving) to Tribeca, while alternating time at a country house in northwest Connecticut.

“Witnessing (my parents) going into the studio day after day, it was just like: ‘Oh, that’s what adults do, and furthermore, that’s what people do,’ ” says Dunham. “I’ve learned since that there’s many other ways to skin a cat, but in our family, it was always the primary mode of expression. Very early on, it made sense to me.”

Says Simmons: “That’s just what we did. We didn’t get outside a lot.”

Simmons, whose work explores female representations through photographs of dolls, miniature interiors and her family, sees her daughter’s work as a “continuation of this sort of female-centric world filtered through her kooky brain.”

She recalls drama teachers in even Dunham’s liberal, pro-self-expression New York private schools reprimanding her for going too far.

“I had my words with them, as you’d imagine,” Simmons says. “Lena would always take the ball and run with it, in a really great way.”

As an undergrad at Oberlin College in Ohio, Dunham began plying her interest in storytelling to filmmaking — “and I was just completely addicted,” she says. Dunham made her first film, “Creative Nonfiction,” about a screenplay-writing student navigating college sex, and an Internet video, “The Fountain,” in which she baths in a campus fountain.

In “Tiny Furniture,” Dunham’s character has returned home to New York (her parents’ actual Tribeca home) from college. There, she wrestles with who she is and her place in the world, themes carried over in “Girls.” Though structured by awkward encounters with boys, the film ultimately hinges on the mother-daughter relationship.

Echoing earlier criticisms of New York filmmakers like Whit Stillman and Noah Baumbach (both inspirations to Dunham), some took issue with her depiction of such a privileged life.

“It definitely was a thing where I was like, OK, I have to be careful with this,” says Dunham. “‘Girls’ is dealing with people who have moved to the big city to find their fortune, which is a wider range of people.”

Enthralled by the movie, Apatow realized Dunham was someone worth meeting once he saw her name again and again in the credits (”directed by,” “written by,” “produced by”). In guiding “Girls,” Apatow (who made the quickly cancelled “Freaks and Geeks” and “Undeclared” before focusing on writing and directing films) has returned to television, he says, “to get her through this experience without getting crushed by the machine.”

“It’s probably extended by creative life as I go into the first stages of exhaustion and generally running out of gas,” says Apatow. “She’s so energized and in her moment. Unlike me, she didn’t have any awful experiences trying to get movies made or have them turn out weird, TV shows get canceled. So she’s just a ball of good energy.”

He adds: “She’s not worried about everybody’s judgments the way most neurotic comedians are. She just thinks you make things, that that’s what life is all about.”

While enjoying a Waldorf salad (“like a 95-year-old woman,” she says), Dunham exhibits only easy modesty and relentless curiosity. The ebbs and flows of good and bad reviews that have punctuated her parents’ careers, she says, has conditioned her to take success skeptically.

Right now, she’s cautiously developing a second season for “Girls,” in case it gets picked up. She plans to adopt a dog in September, either a pug-Chihuahua mix or a dachshund-Chihuahua mix — “small enough to fit in a bag, but not fully a Chihuahua.”

Dunham, a filmmaker who has transitioned with ease from film sets of six to soundstages of 60, clearly has herself more together than her characters. But she also has a dawning realization that even as she finds her way, uncertainty isn’t about to vanish.

“I wished that it passed by the time you were 26, but I’m hearing that that’s not the case,” she says. “I’m always like, I make movies about this. Shouldn’t I move past it? That’s not how it works, unfortunately.”