Jared Leto lived his role on 'Dallas Buyers Club'

Jared Leto as Rayon in the fact-based drama "Dallas Buyers Club."

Attention, shoppers — that woman in the checkout line may be Jared Leto.

The actor still recalled as Jordan Catalano from the brief series “My So-Called Life,” and the crush of many teenage girls in the ’90s, lands in theaters Friday in the so-called role of his life. He stars in “Dallas Buyers Club” as Rayon, a heartbreakingly vulnerable but business-savvy transgender AIDS victim.

“As soon as I got out of the van [the first day of shooting], I had my high heels on, and I was in it,” says Leto. “I was in character every day I shot.

“It’s not a new thing [this kind of immersion], but it was essential. There was too much to lose if I didn’t do it.”

Leto even stepped out in costume to a Whole Foods near New Orleans, where much of the film was shot.

“I got some ... distinct looks,” he says. “One look was, ‘What is that?’ Another was, ‘I don’t know what that is, but I don’t like it.’ But that condemnation and judgment I got — that was important to the role.”

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In director Jean-Marc Vallee’s fact-based drama, Matthew McConaughey plays Ron Woodroof, a Texas party-boy electrician and part-time rodeo rider diagnosed with AIDS in 1985. An undisguised homophobe, Woodroof nonetheless joins forces with Rayon when he finds trafficking in unapproved pharmaceuticals from outside the U.S. could make him money — and keep him alive. So the two tap into a sadly ever-increasing clientele for what they call the Dallas Buyers Club.

There’s been consistent Best Supporting Actor Oscar buzz around the 41-year-old Leto since “DBC” debuted at the Toronto Film Festival in September. And no surprise, since the Louisiana-born, California-raised actor who attended New York’s School of Visual Arts spent the entire production as Rayon.

The Whole Foods visit was “only to buy water,” Leto says, since he estimates that he shed “30 or maybe 40 pounds” to play someone in the final stages of AIDS.

It’s not the first time he went through a massive physical transformation. For the 2008 indie “Chapter 27,” he gained 60 pounds to play Mark David Chapman, killer of John Lennon.

After playing Claire Danes’ love interest in “My So-Called Life,” which ran on ABC from August 1994 to January 1995 but attained a cult following, Leto dove into a gallery of disparate roles: doomed runner Steve Prefontaine in “Prefontaine” (1997); a white-haired militant in “Fight Club” (1999); a heroin addict in “Requiem for a Dream” and a pal/victim of serial killer Patrick Bateman in “American Psycho” (both 2000), and a thief in “Panic Room” (2002).

The same year “Panic Room” came out, Leto’s band Thirty Seconds to Mars — which he formed in 1998 with his brother, Shannon — released their first album. The band’s success, and two subsequent albums, kept Leto out of major movies for several years by his own choice.

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After playing arenas around the world, his high-profile return to films is as a composite character from Woodroof’s life. Yet the performance was informed by Leto’s personal experience.

“When I first moved to Los Angeles in the early ’90s, I rented a room in a house, and one of the other rooms was rented by a man in his 40s who was dying of AIDS,” he says. “I watched week after week as he withered away. It was a very impactful experience. He was kind, funny, full of grace and charm — a lot like Rayon.

“It was [also] really important for me for Rayon to be a transgendered person, not a drag queen,” he continues. “One is a person who just enjoys putting on women’s clothing, the other is someone who wants to live their life as a woman, who identifies as a woman. It’s a key description that wasn’t in the script, but it felt important to the character.”

Leto, who jokes he “never actually met” McConaughey until the Toronto Film Fest — because that was Rayon who filmed with him — says it wasn’t an issue not hanging out with his co-stars. “I didn’t go to lunch because I wasn’t eating.”

Still, Oscar buzz or not, he feels that it might be time for another about-face.

“There are no rules for any of this,” Leto says. “Maybe I’ll get cast as myself in a film. Then I’ll have to come in character as myself.”

Sounds like James Franco may have some competition in that department.