The supermodel mum of two is approaching 40 but her looks have hardly changed since she emerged on the international fashion scene aged 17. The secret to her eternal youth? Ian Marber, the Food Doctor, a nutritionist used by Leona Lewis and many of the world’s top model agencies. The main principles of Marber’s eating plan are, eat more not less, but only of the right low GI foods including lean protein, chicken breast, fish, veal - and cereals, seed mixes, brown rice, fruit and veg. He recommends eating every two to three hours to maintain stable blood sugar levels. This prevents cravings for sweet sugary foods, and gorging when you finally eat after long gaps between meals, plus balancing the carb and protein content of meals. For lunch he advises 40% protein, 40% vegetables and 20% complex carbohydrates. Dinner is 50% protein and 50% vegetables and does not contain complex carbohydrates. (It’s similar to the Zone diet favoured by Jennifer Aniston) Marber’s meal combos include toasted cereal, yoghurt, seeds and fruit for breakfast, carrot leek and watercress soup for lunch, and dishes such as Chinese five-spice lamb, Mediterranean risotto and spicy roast ratatouille for dinner.