Actors slimming down or bulking up for movie roles is nothing new — from Robert De Niro's famous weight gain to play an aging boxing champ in Raging Bull to Christian Bale's dramatic body changes in, well, practically everything he does. Even so, there's something remarkable — if not a little disconcerting — about Zac Efron's physical transformation for The Iron Claw, a dark sports drama that sees the former High School Musical star re-sculpted as a tragedy-stricken professional wrestler. With his rippling, vein-streaked biceps, volcanic traps and a jawline you could plan a city around, Efron less resembles a...