The GI diet

It's not just about low-carb diets anymore, carbohydrates are now being assessed by their effect on your blood sugar levels. Find out more about the Glycaemic Index with our guide.

Start talking about nutrition and sooner or later the subject of GI foods will crop up. They have become nutritional buzzwords in the past few years but do you know what GI refers to?

The Glycaemic Index (GI) is a way of rating foods according to how quickly they can be digested and converted to glucose, your body's energy source. Foods with a high GI rating cause a rapid rise in blood sugar levels while those with a low rating result in a steadier, more gradual rise.

Many of us have diets which incorporate mostly foods with a high GI rating such as potatoes, white rice, refined breads, cereals, biscuits and sugary foods. They all provide a quick surge of energy to the body but this peak is shortlived and as soon it subsides the body usually starts to crave another high glycaemic food for a repeat energy fix. This can trigger a cycle of energy peaks and troughs fuelled by high glycaemic snacking which can lead to overeating and weight gain.

The only way to break the cycle is to include more foods with a lower GI rating in the diet, such as oats, pulses, oatmeal bread, fresh and dried fruits. These provide a more constant supply of energy which helps to avoid the yo-yo effect ensuring you feel awake, alert and ready for anything all day long.

A diet that achieves a balance between high and low GI foods tends to be healthier not least because it prevents the cravings for fatty, sugary foods that often arise when blood sugar levels fall. It will also leave you feeling fuller for longer so your appetite decreases and you may even lose weight.

Research also shows that low GI diets help to control diabetes by improving blood sugar and fat metabolism. They may also help to prevent the onset of Type II diabetes.

To get started, go for breakfast cereals based on oats, barley and bran and buy 'grainy' breads made with whole seeds. Reduce the amount of potatoes you eat and increase the amount of fruit and vegetables including salad in your diet. An ideal breakfast would be porridge with raisins, for lunch, a jacket potato with baked beans and a sprinkling of cheese and for supper, stir fry chicken breast, green vegetables and noodles.

Reading the GI
Pure glucose produces the largest rise in blood sugar levels and has a GI reading of 100. All other foods are ranked from 0-100 according to their effect on blood sugar levels.

High GI foods (70 or more) should make up less than 10 per cent of your diet
Medium GI foods (69 - 56) should make up 30 per cent of your diet
Low GI foods (55 or less) should make up 40 per cent of your diet

High GI foods : Honey, Potatoes, Parsnips, Bananas, Butter, Cheese, Cream and Full-Fat Milk, Wheat Flakes and White Bread, red mean and all processed foods, Pasta and Rice, pastries, biscuits, cakes, Chocolate, Cashews, Peanuts and Pistachios, Alchohol, tea and coffee

Medium GI foods: pineapple, strawberries, skimmed or soya milk, wholemeal bread and pasta, brown rice, cous cous, oats, sunflower and pumpkin seeds, sweetcorn, muesli, raisins and beetroot,

Low GI foods: Apples, appricots and cherries, fresh dates and figs, mangoes and pears, asparagus, aubergines, broccoli, cabbage, carrots and cauliflower, celery, courgettes and leaks, sweet potato, spinach, turnips, butter beans, kidney beans, soya beans, chickpeas, lentils, almonds, brazil nuts, sesame seeds, fish oils, nut oils, avocado oils, millet, quinoa and wild rice.

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The GI Diet FAQ's