The aud at Monday’s Variety screening of “The Machinist” was understandably intrigued by topliner Christian Bale’s enormous weight loss for his role as a man literally wasting away from a guilty conscience.“I usually say I did it through copious amounts of drugs, but my mother-in-law and wife’s grandmother are here, so, I did it by conventional dieting,” Bale said. The thesp bristled slightly at the inevitable questions revolving about his 60-pound weight loss. “In no way would I like this to be seen as a gimmick,” he said. “I would have to be an idiot to do this for a movie that wasn’t worth it.” Co-star Jennifer Jason Leigh, helmer Brad Anderson and scribe Scott Kosar also relayed anecdotes about Par Classics’ drama. Pete Hammond moderated the ArcLight sesh.