Dramatic diets for the sake of on-screen authenticity are most frequently associated with Western screen stars Christian Bale or Matthew McConaughey. But festival-goers in Macau this month will have a chance to witness an equally amazing transformation wrought by Deng Chao, one of China’s top actors.

Zhang Yimou’s “Shadow” has been added as the closing feature for the International Film Festival & Awards Macao. In the film, Deng plays both a 6th century general and his body double. The complication is that one version of the warrior is fighting fit, the other is hollowed out and dying.

Zhang and Deng achieved the incredible bluff by shooting all of Deng’s buff warrior scenes first. Production was then interrupted for nearly two months while Deng engaged in a crash diet, to emerge skeletal, goggle-eyed and aged.

Picking up the shoot after the break was harder than envisaged. The script calls for the two versions of Deng’s character to interact, and even fight.

“Two months later, we shot a scene where they clink cups as a toast. We found that after such a lag it was especially hard to get the two cups to line up correctly. So we stretched out a bunch of wires and strings to mark the position,” Zhang told Variety.

“Shadow” producer Ellen Eliasoph added: “We mounted motion sensors on cables that could actually pick up when the touch was right, and the action lined up with what had already been shot. There was also a red light that Deng Chao could also see and move towards.

“It was like being in a pachinko parlor because when it hit, there came a ‘pa-ching’ sound that everyone on set was listening for. We thought it was really funny, but it proved to be the most amazing tool for realizing (this way of stitching together motion from different shots). I don’t think anyone’s done this before.”

“Shadow” emerged as the numerical winner from last month’s Golden Horse Awards, collecting four prizes including best visual effects for Samson Wong, as well as an acting nomination for Deng.

“’Shadow’ is a visually extraordinary film which will have audiences agape at the spectacle on show. It is also a riveting story of intrigue and deception set in the court of an ancient kingdom. We are reminded with Shadow just what an unrivalled cinematic storyteller Zhang Yimou is, and feel it is the perfect film with which to close our festival,” said Mike Goodridge, the IFFAM’s artistic director. The festival runs Dec. 8-14.