ARCADIA, CALIF. — Fortified by coffee and a Red Bull on the Sunday morning before Christmas, Brie Larson was hopscotching down a path at the Los Angeles County Arboretum and Botanic Garden here. It was unseasonably cool for Southern California, but she was just happy to be outside, walking (or jumping) around.

Ms. Larson, 26, has been in show business for nearly 20 years, appearing on sitcoms (“Raising Dad”) and prestige cable shows (“United States of Tara”), starring in lauded indie movies (“Short Term 12”) and even making a brief run as a teen pop star (you may remember her album “Finally Out of P.E.”). But nothing has prepared her for all-consuming nature of the movie awards season.

Her portrayal of Ma in the harrowing “Room” — she plays a young woman imprisoned by a sexual predator, with only the 5-year-old son she bore in captivity giving her the will to keep going — has catapulted her into contention for a leading actress Oscar. (She already has nominations for a Golden Globe and a Screen Actors Guild trophy.)

And that means a monthslong swirl of politicking, interviews, film festivals and awards shows. Ms. Larson jokes that she’s probably spent more time talking about “Room” than the 49 days she was actually on set filming it.

Combine that with a just-completed three weeks of night filming in Hawaii on “Kong: Skull Island,” her first Hollywood tentpole and one in which she has a starring role, some communing with nature may be just the ticket to maintain her equilibrium — and sanity.

“I’m trying to find new ways to entertain myself, because if my whole world is doing interviews, I might as well put them in places I’ve wanted to see,” she said with a laugh during yet another interview.

Though Ms. Larson decided at 6 that she wanted to be an actor, her career choice still surprises her.

As a child, first in Sacramento and then Los Angeles, she was painfully shy, afraid of eye contact and wary of social interaction. “My parents called me the WB frog,” she said. “Because when I was onstage, I would do this whole song and dance, but if my parents had a family friend over, I would just go hide in the bedroom.”

Ms. Larson has overcome that phobia, realizing that the social awkwardness she thought was uniquely hers is shared pretty much by everyone. Since her first TV appearance, in a fake Malibu Mudslide Barbie commercial on “The Tonight Show With Jay Leno” in the late 1990s, she’s carved out a career filled with eye-catching supporting turns in films like “Greenberg,” “21 Jump Street,” “Rampart” and, this past summer, “Trainwreck” (in which she played the sister of Amy Schumer’s character).

But it was her starring role in “Short Term 12,” a 2013 drama in which she played a supervisor at a group home for at-risk adolescents, that put her on the short list for films like “Room.”

“She’s not trying to show you how great an actor she is all the time,” said Lenny Abrahamson, the director of “Room.” “There’s a deep naturalistic impulse in her acting. I think we rather fetishize a kind of showy intensity in our actors, which I’m not interested in.”

Ms. Larson may not be an extreme Method actor, but her preparation for “Room” was just as exacting.

For research, she read widely about trauma and spent hours each week talking to an expert at the University of Southern California. And to capture a body falling apart — what seven years locked away would physically do to someone, even as she struggled to remain strong — she embarked on an intense, if subtle, makeover.

Staying indoors and out of the vitamin D-giving sun furnished Ma’s pallor and dulled hair. Hard-core workouts with a trainer and a protein-packed diet of six (very) small meals a day for six months translated 15 pounds of fat into muscle, resulting in a sinewy look. Circles under the eyes and yellowing teeth completed the transformation.

All that preparation gave Ms. Larson’s portrayal of Ma a certain fierceness — which leeched into her real life.

Over brunch at a nearby hotel, diet dispensed with as she ravenously dug into a coffee poundcake, she recounted returning to her car after a meeting with Mr. Abrahamson to discover a traffic agent writing up a ticket. Ms. Larson, who typically would meekly accept the ticket for a just-expired parking session, instead angrily chewed him out.

Afterward, she sat shaking in the driver’s seat, dumbfounded. “I felt like this Hulk was taking over my body,” she said. “I had never experienced anything like that before.”

She got the ticket, anyway.

Her research doesn’t usually lead to such drastic behavior changes. Before filming “Trainwreck,” Kim Caramele, Ms. Schumer’s sister and the model for Ms. Larson’s character, had plenty of what seemed like regular conversations with Ms. Larson. It wasn’t until the cameras were rolling that Ms. Caramele noticed that Ms. Larson had perfectly adopted her mannerisms. The lousy posture — hunched over, arms crossed, as if she’s angry with the world — and the exasperated-yet-still-affectionate eye-rolling at Ms. Schumer’s more inappropriate comments were somehow all there.

“It never felt like she was studying me,” Ms. Caramele said.

That striving for fidelity comes from a deep-seated respect for the medium of movies. “I know how important they’ve been to my life,” Ms. Larson said. “Before I was old enough to have the money to travel, it was how I saw the world. It’s how I saw different people. It was how I saw different countries. It was how I saw different eras. And I believed them.”

(Ms. Larson now serves on the advisory board of the Cinefamily, a Los Angeles nonprofit devoted to presenting “exceptional, distinctive, weird and wonderful films,” according to its website. There she started the monthly Women of Cinefamily program, showcasing movies starring or directed or written by women.)

A seemingly effortless ability to blend the serious and the comic has also drawn directors to her.

“She’s great at playing complex emotions, and she’s really, really funny,” said Judd Apatow, the director of “Trainwreck,” who first noticed her in “United States of Tara,” where she played the rebellious daughter of Toni Collette’s character. “And that’s a very rare combination.”

So, too, is the melding of relatable characterizations with leading-woman acting chops.

“The situation of Ma is so tragic we don’t want somebody who looks as if she was born to tragedy, who’s got one of those faces that are all cheekbones,” said Emma Donoghue, the author of “Room,” who also wrote the screenplay. “And Brie’s got a capacity to show a very ordinary, humorous girl-next-door, down-to-earth kind of side.”

Ms. Larson can glam it up — a prerequisite on the draining awards season trail. On this Sunday morning, she’s a wearing a black Gucci dress for a photo shoot. But she’s paired it with Ugg slippers, leggings (her mom’s) and comfy socks.

At the Arboretum, her choice of footwear does receive some admiring glances, but no one seems to recognize her, much to her relief. Losing that anonymity for good scares her. She clings to the hope for a private life that stays private, participating engagingly in the interview while still declining to divulge where exactly in Los Angeles she lives. “I’d rather not say, because then the Hollywood star tours may try to find me.” (She does allow, when pressed, that she is in a relationship.)

But as the awards season jockeying turns into the homestretch, she’s made her peace with surrendering to the publicity machine. Spying a Snugli-wearing visitor to the botanical gardens, she makes a wistful wish.

“I just want to be in that, to be carried around like that baby,” she said, laughing. “That’s what I need. If only I could find a person tall enough to carry me around.”

Source: New York Times