April 03, 2015 08:35 AM

Wild debuted a new side of Reese Witherspoon – bruised, tangled hair, dirty and barefaced.

PEOPLE got an exclusive look at the making of the film adaptation of the 2012 best-selling memoir, and it captures just how much physical and emotional labor the Oscar-nominated actress endured to portray one of her most vulnerable characters to date.

“It’s a very unorthodox system of filmmaking – more than I’ve ever done before,” she says in the behind-the-scenes featurette. “It frees you of old patterns that you’ve had.”

In case you missed the Oscar buzz surrounding the drama, Wild tells the real-life story of Cheryl Strayed, a woman reeling after her mother’s sudden death, who decides to hike the 1,100 miles of the Pacific Crest Trail in order to overcome grief and rediscover herself.

How did the Witherspoon, 39, strip down to bring Strayed’s memoir to the big screen? No makeup and 75 lbs.’ worth of camping gear strapped to her back, for starters.

“Reese agreed to go with no makeup on the trail just so she could feel what it is to go on a hike and not focus on looking at yourself,” director Jean-Marc Vallée says in the clip. “She had a real backpack on,” he adds.

Witherspoon credits her offscreen friendship with Strayed as a major motivation to portray her journey truthfully.

“[Cheryl] was standing there on set the whole time. She’s so giving,” Witherspoon told PEOPLE in November. “She really gave us license to interpret it and turn it into a movie.”

For more behind-the-scenes moments, pick up Wild on Blu-ray and DVD.

RELATED VIDEO: Inside Reese Witherspoon’s Oscar Glam Day

You May Like

EDIT POST