Kristen Stewart, the Twilight actress who is known for her petite, slender frame has reportedly gained weight for the film she just finished filming in Germany.

According to OMG! Yahoo, she was asked by director Olivier Assayas to beef up for her role as a personal assistant for her upcoming film Sils Marias.

A source told the website that Assayas wanted Stewart to look "dowdy and puffy" to transform into the role as the right hand to the character played by Julette Bincohe. The insider revealed that she successfully put on more weight by consuming more calories than usual.

Another insider told Showbiz Spy she indulged in sweets-- chocolate squares, specifically to successfully add a few pounds.

Stewart was also asked to dye her hair and lighten her brunette locks to a specific shade of auburn, according to Yahoo's source.

See Kristen Stewart's most recent photo with her weight gain andhair color change here.

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While she was in France attending Paris Fashion Week in July, Stewart shared with WWD that she plays "a personal assistant to an actress" in the drama.

Binoche will portray a character named Maria Enders. Binoche once played the onscreen lover ofStewart's ex-boyfriend Robert Pattinson in his 2012 indie hit CosmopolisSils Maria also stars TomSturridge, a British actor who is a great friend of Pattinson.

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Stewart reportedly returned to Los Angeles on Oct. 5 after filming the movie for two months in Berlin, Germany.

When she flew to Berlin in July, she sported a new tattoo on the inside of her right arm when.

See the photos of Kristen Stewart's new tattoo here.

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