The girl in Wagamama looks puzzled as I tell her: 'All I eat is edamame beans.' She looks at my thighs. She looks at me. She's too polite to comment so I help her out. 'No,' I say, 'I haven't been on this diet very long.' I've been on the diet for 11 hours to be precise. Ever since I decided to follow Victoria Beckham's diet for a week