Why? Just take a look of the window: it's gray, cold and damp. Viruses and germs lurk in the office, that end-of-year feeling of tiredness begins to set in...in short, now's not the time to impose deficits on your body. In winter, more than in any other season, our bodies need vitamins (C, A and E particularly), as well as minerals and trace elements (magnesium, iron, calcium and copper) we need to cope with the ravages of winter.
How? The best sources of vtamins, minerals and trace elements are fruit and vegetables, in all forms. They're also low-calorie foods, so get stuck in! For 2 weeks, you're not going to deprive yourself, even if it means exceeding your recommended fruit and veg quota (5 portions per day, or around 400g - 600g). On this diet, you eat a piece of fruit with every meal, including breakfast, and as much veg as you like (cooked without fat) at lunch and dinnertime.