She's always been one to jump on the latest diet bandwagon, whether its working up a sweat at bootcamp or promoting a slimming shake. But Kim Kardashian's latest get in shape plan is an invention all of her own - the 'sex diet'. As the reality star showed off her beach ready curves in Miami it emerged that she had honed them with the help of boyfriend Kanye West. A close friend told the National Enquirer: 'We jokingly refer to it as the sex diet. When one of us is having regular sex, that tends to burn calories and kill the appetite. 'Losing seven pounds in seven days means being a very naughty girl.' Kim showed the results of her special workout as she stepped onto the beach in Malibu last week. With her publicicst friend Jonathan Cheban at her side, she walked in a black sarong, tied over a black and bright orange strappy bikini.