has told Sienna Miller she can lose weight on a diet of curry powder and "lots of sex".Sienna was forced to pile on the pounds for her role in new film 'Hippie Hippie Shake', and the 'Fight Club' star has recommended his unique weight-loss technique as a great way to slim back down.A source told Britain's Daily Express newspaper: "He can lose 14lbs in a month on an all-liquid diet by mixing water with curry powder or pepper and combining it with lots of sex."Apparently Sienna was amused by his advice as she has had to put 7lbs in the past few weeks for her role as a flower child in the film 'Hippie Hippie Shake'."Jared, 35, was introduced to Sienna by 'Notting Hill' star Rhys Ifans - who is rumoured to be dating Sienna - while filming 'Mr. Nobody' in London.Jared and Rhys both appear in 'Mr. Nobody', in which Jared stars as Nemo Nobody, a normal man who is enjoying a run-of-the-mill existence with his wife and three children when he suddenly wakes up as a 120-year-old man in the year 2092.Sienna and Rhys have been spotted together frequently in recent weeks, sparking rumours their close friendship has blossomed into love.