Hayden Christensen and Sienna Miller

Sienna Miller went on a vodka diet to lose weight for her latest film.The slim 24-year-old actress had to get down to a controversial size 0 for her role as Edie Sedgwick in new movie 'Factory Girl'. Sedgwick was revered artist Andy Warhol's muse and an 'It' girl of the mid-60s, who was addicted to drugs and suffered from depression and bulimia. So Sienna, who recently split for good from her sometime boyfriend Jude Law,resorted to drastic measures to make sure she accurately resembled her troubled character. She is quoted as saying: "I decided to drink vodka instead of wine because it has less calories."Another of her sliming techniques was to eat omelettes made only of egg whites. Sienna stars opposite Guy Pierce, who plays Warhol, and Hayden Christensen who plays Sedgwick's fictional lover Billy Quinn - who is believed to based on three of her real life partners, Bob Dylan, the late Doors singer Jim Morrison and Sir Mick Jagger. Sedgwick tragically died at the age of 28 from a barbiturate overdose.