How to follow the GI diet

While losing weight, aim for 2-4 points for breakfast; 4-6 points each for lunch and your main meal, and 1-3 points for your snack.

Include plenty of free foods and make up your daily points from as many 1-point foods as you can. The more you include, the less hungry you'll feel.

Remember one of the most helpful aspects of a GI diet is you don't have to weigh and measure everything. On this diet exact amounts of food are rarely given, and in the seven-day diet plan, a medium portion means a helping that's enough to satisfy your appetite.

A food's points value relates to a normal portion. You can mix and match same-points foods to make up a normal portion. For example, small portions of three or four 1-point fruits would make up a fruit salad with a 1-point value.

Eat bigger portions of low-point foods that have a low points value, such as vegetables and fresh fruits, and smaller portions of 3-point foods. As a rough guide, normal portions of some frequently used items of food can be calculated as follows: oil, 1tbsp; butter, 2tsp; vinaigrette, 1tbsp; sugar or honey, 2tsp; dried fruit, medium palmful (40g to 50g); nuts, small palmful (50g); seeds, 1 rounded tbsp (30g); hard cheese, 1 matchbox-size piece; Brie type, 1 matchbox-size piece.

When choosing food to eat as a snack, make sure that it doesn't just consist of a 3-point item and nothing else. Your snack should be selected from the free, 1 or 2 points lists: this way it will be something that's digested slowly and will see you through to your next meal.

Alcohol is counted as 3 points. This means an average glass of wine, a 300ml bottle of lager or a double measure of spirits counts as 3 points. So if you're aiming to lose weight by following the diet, it is wise to limit yourself to a maximum of one of these drinks a day, with your evening meal. But it's best not to drink alcohol every night: just three or four times a week is better until you reach weight-maintenance stage.

If you don't need to lose weight, you can increase your daily points limit to 20. If your weight doesn't remain stable at this level, increase or decrease your points accordingly until it does.

Click here for our three lists of foods rated 1, 2 or 3 points - plus a ‘free' list

To guarantee weight loss, some foods that may be low or moderate on the classic GI scale, but which are high in calories or fat, have been given 3 points. And protein foods, such as meat and fish, and certain fats that aren't on the GI index (because they contain little or no carbohydrate) are rated under ‘equivalents'. To make the plan work for you, eat all you like from the ‘free' list. Then pick three meals, plus one snack a day, from the other lists, making sure your daily points total comes to no more than 15.

Eat three meals and one snack daily Never skip breakfast and make all meals about the same size. Good snacks include olives, nuts (50g a day), plain popcorn, crudités with a low-fat sour cream or hummus dip, individual pot low-fat fruit yogurt or fromage frais.

Always ask for wholemeal or wholegrain bread when buying sandwiches and discard the top slice. Vegetable soups with low-GI beans or lentils, and pasta and bean salads with low-fat dressing are good lunchtime options.

When eating out avoid pastry/bread-based nibbles and choose olives or nuts instead. Aim for vegetables to take up 50% of your plate, meat or fish 25%, and rice, pasta or potatoes 25%.

Remember to choose wholegrain bread over white; basmati over short grain rice; boiled new potatoes over baked or mashed; bulgur wheat over couscous.

Opt for whole fruit rather than juice - the GI is lower and your body also has to work harder to break it down.

Treat yourself. If you do need a boost - particularly in the middle of the afternoon - choose two or three squares of dark chocolate such as Green & Blacks, which has a high cocoa-solid content and is lower in sugar and fat than regular chocolate. Other treats include a low-fat ice cream, a small packet of low-fat crisps/corn chips, or a glass of wine.

Keep serving sizes realistic (100g for meat and fish, 40g pasta, 50g rice) and fill up on vegetables and salad.

Don't forget to check the fat content of food Only carbs are measured on the GI index, so keeping your fat and calorie intake low is just as important as eating foods with a low GI.

Think balance It's the overall GI effect of each meal that's important, not the individual rating of each food. If you're really craving a high-GI food, go ahead, but balance it with plenty of low-GI foods, such as vegetables, pulses and fruits.