1. Drink 10 to 12 glasses of water a day. Water flushes toxins from your system, cleanses the liver, and can help fill you up. Look at the label of the soda that you drink and select those that have no sodium. You can vary the taste of the water by adding a slice of citrus fruit, or a tablespoon of fruit juice. Cut down on coffee and teas, both are mildly diuretic, which means they remove water from your system. That's not what you want.
2. Cut your meals in half. Prepare half of what you normally have for breakfast. Replace the half you're missing with a piece of fruit. Only eat half your sandwich at lunch. Add a small salad with no fat dressing in its place. At dinner time split the entrée with someone else. Order a cup of soup, not cream soup of course, to fill you up. If you have dessert, share it.
3. Keep a food journal. The very act of recording what you're eating will probably mean you'll eat less. Keep a small notebook in your desk, purse, or briefcase. Write down what you're eating right after you've finished. If you wait until the evening it will be oh-so-easy to forget that you had a mocha cappuccino with a cookie, as a midmorning pick me up. It can be a shock to see how much you're really eating. You can also use the journal to record how you're feeling, and what you're doing, right before you eat or while you're eating. After a few days it may become obvious that a visit from an office mate means a run to the candy vending machine. Or that you mindlessly munch on chips while a certain TV program is on.
4. Use the 80 – 20 principle. Make sure that 80% of your diet is made up of vegetables and fruits (no, potatoes are not a vegetable in this case) and 20% protein, carbohydrates, or fats. Veggies and fruits have huge amounts of antioxidants, vitamins and minerals. They taste good, and are bulky which fills you up. Steam, grill or roast the veggies. You can also roast fruits or grill them. It brings out the sweetness and is a nice change from raw fruits. Eating this way for 5 days will most likely result in a 5 pound loss and won't hurt you for such a short time. If you're worried about cutting down on the protein so much, you could add tofu.