Glycaemic Index

The rate at which carbohydrate is broken down to provide glucose (sugar) in the blood stream is called the glycaemic index (GI) of food.

Foods with low GI values generally cause a lower and more gradual rise in blood glucose (particularly beneficial for people with diabetes). In contrast, foods with a higher GI value are broken down rapidly, causing a quick rise in blood glucose levels. The GI can differ between foods for a number of reasons, including methods of processing and cooking used and the size and nature of starch molecules present in the food.

In general, low GI foods are those with a GI below 55, while high GI foods are those over 70. Most legumes, oats, barley, pasta and many fruits have a low GI. Other healthy lower GI choices include low-fat milk or soy drinks, low-fat yoghurt, high fibre or bran cereals, multigrain, kibbled and barley breads, some varieties of rice (such as doongara and basmati), and vegetables (such as peas, sweet corn and kumara).

Low fat, low GI foods make good dietary choices. Low GI foods eaten as part of a meal can lower the overall GI of the meal, thereby slowing the rise of glucose in the blood stream after a meal. Try to include low GI foods in meals and snacks where possible. Low GI foods help you to feel full, boost energy, avoid rebound hypoglycaemia and even out blood glucose levels.

Low GI foods are also best to be eaten prior to exercise in order to provide a slower release of fuel for the duration of exercise. High GI foods should be eaten after intense exercise in order to quickly replenish vital energy stores.

Fat in foods can delay the emptying of food from the stomach. This explains why some high fat foods have a low GI. However, to limit excess fat intake, choose low-fat, low GI foods in preference to low GI foods that are high in fat.

The GI of common foods

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