The Glycaemic Index (GI) is a system of classifying carbohydrate foods based on their effect on blood glucose (sugar) levels. Foods are given a rating between 0 and 100.
The use of the GI has been shown to be particularly useful in the diets of people with diabetes and people at high risk of developing diabetes. However research suggests that considering the GI of foods as part of a healthy eating plan, may be beneficial for all adults, in helping to maintain a healthy weight and preventing type 2 diabetes 1,2.
Carbohydrate foods can be classified as having a low, moderate or high GI. Low GI foods are those that have a slower, more constant affect on a person's blood sugar levels. That means, they break down slowly and generally provide a longer 'feeling of fullness'. Taking this into consideration, a diet based on low GI foods can be useful to prevent overeating and maintain more optimal blood sugar levels.
Classification of GI values.
Low GI = 55 or less
Moderate GI = 56-69
High GI = 70 or more
The GI of a food should be considered along with the food's other nutritional attributes such as fat, sugar and salt content. Some high fat foods have a low GI, such as chocolate, ice-cream and toasted muesli. Similarly, most sugary foods have a low to moderate GI. However, this does not mean these foods are the healthiest foods for everyday eating.
But what about an entire meal?
As most of us eat many different foods at the one meal, it is important to consider the GI in this context, rather than simply rating individual foods. The GI of all foods eaten as part of a meal, will contribute to the overall GI. The overall GI of a meal can be lowered by the addition of a low GI food. For example, adding low fat soy or dairy milk and canned fruit, both of which have a low GI, to a moderate GI breakfast cereal will create a low GI meal.
So what should you eat with regard to GI?
Try to include a low GI food at every meal, including snacks where possible. However, not all your foods need to be low GI as other foods that have moderate or high GI's including some fruit, can contribute to a highly nutritious diet. In choosing foods, whether low, moderate or high GI, make sure they are low in fat, particularly saturated fat, low in salt and added sugars, high in fibre and above all.. tasty!
Glycaemic Index (GI) of Common Foods 3:
| Low GI | Moderate GI | High GI | |
| Fruit | apple pear orange |
apricot pineapple mango banana |
Watermelon dates |
| Vegetables* | Sweet potato (Kumara), yam Sweet corn Taro Peas |
Most potatoes (whole/mashed/ instant potato) | |
| Bread | Mixed grain breads Pumpernickel bread Sourdough bread Rye bread Fruit bread |
Wholemeal bread Crumpet |
White breads Bagel Gluten free bread English muffin |
| Cereals | Porridge Natural muesli |
Sanitarium Weet-Bix | Many refined cereals such as cornflakes, puffed wheat, popped rice |
| Rice/Pasta | Spaghetti & most other pasta/noodles Barley Buckwheat |
Basmati rice Doongara rice Gnocchi Cous cous |
Calrose white rice Jasmine rice |
| Milk & alternatives |
Milk Sanitarium So Good® Low fat fruit yoghurt Custard |
||
| Other foods | All legumes such as lentils, soybeans, split peas, baked beans, kidney beans Oatmeal biscuits |
Wheat biscuits Crispbreads with grains |
Water crackers |
References
1. Brand-Miller JC, Holt S etal. Glycemic Index and Obesity. Am J Clin Nutr 2002;76(suppl):281S-5S.
2. Ludwig DS. The Glycaemic Index - Physiological Mechanisms Relating to Obesity, Diabetes, and Cardiovascular Disease. JAMA 2002;287(18):2414-2423.
3. Brand-Miller J & Foster-Powell K, 2000. The Glucose Revolution- GI Plus. Hodder Headline Australia Pty Limited.
