How Wild star Reese Witherspoon was stretched by director's stripped-down style

While filming Wild, director Jean-Marc Vallee set ground rules for lead actress Reese Witherspoon: she couldn't wear make-up, had to cover the mirrors in her trailer, and wasn't allowed to lighten the load in the comically massive backpack worn by her character, Cheryl Strayed.

"The film is called Wild, not 'Nice' or 'Sweet'," Vallee says of his stripped-down approach to filmmaking that relies on natural light and handheld cameras.

The 51-year-old Montreal native has worked as a filmmaker for more than 20 years in Canada and the US. But he's enjoying increased recognition in Hollywood recently as a director who shepherds actors through some of their strongest and most taxing performances, dexterously capturing the trickiest special effect: human emotion.

Dallas Buyers Club, Vallee's raw 2013 drama set during the 1980s Aids crisis, won Oscars for Matthew McConaughey and Jared Leto, who showed audiences a new range beyond their heartthrob personae.

Wild stretches Witherspoon - nominated for an Oscar along with Laura Dern, who plays her mother - well beyond the chipper roles for which she's best known, including her Oscar-winning turn as sweet but steely June Carter in the 2005 Johnny Cash biopic Walk the Line.

An adaptation of Strayed's bestselling 2012 memoir of her 1,760km solo hike on the Pacific Crest Trail, which stretches from the US-Mexico border to that between the US and Canada, the film tracks its protagonist's inner journey as she recovers from the sudden death of her mother Bobbi, a painful divorce, and reckless experiences with sex and drugs.