The Glycemic Index & food list

A low Glycemic Index diet will produce greater weight reduction than an equivalent low energy diet which was not designed to achieve a low insulin response.

The Glycaemic Index (GI) is a method of assessing and classifying the blood glucose response (glycaemic response) to carbohydrate-containing foods.  It is a ranking of foods based on their glycaemic impact in comparison to a standard food, usually white bread or glucose.

How is it Calculated?
Eating foods containing carbohydrates results in a rise in the level of glucose circulating in the blood.  Insulin quickly controls this rise.  It is this rise in blood glucose levels which is used to determine the Glycemic Index of a food.

What May Influence the Glycemic Index of a Food?

Type of Carbohydrate

Sugar versus starch
In the body there is no bioloGlycemic Indexcal difference between the Glycemic Index of foods made with and without sugar.  The Glycemic Index lowering effect of sucrose is related to the fructose content of sucrose (1 molecule of glucose joined to 1 molecule of fructose)

Glucose versus fructose
Fructose Glycemic Indexves a lower glycaemic response than glucose.

Amylose versus Amylopectin
These are found in starch.  Foods which have higher amounts of amylopectin, which are easily digested, have a higher Glycemic Index.  Starchy foods contain 25-30% amylose and legumes 30-40%.  Basmati rice has a lower Glycemic Index than calrose rice.

Processing Methods
Highly milled cereals break up cell walls and this results in these foods being digested more quickly.  For example, rice bubbles and wholemeal bread will Glycemic Indexve a higher blood glucose response than will wholegrain rice and wholegrain bread.

Dietary Fibre
Viscous fibres in fruit, vegetables and grains, such as oats, exert a minor Glycemic Index effect.

Fat
Fat reduces Glycemic Index.  When fat is added to a food, such as potato fries, this will have a lower Glycemic Index than a plain potato.   However, due to the added saturated fat this is not a health advantage!

Applications of the Glycemic Index

Weight loss Management - low Glycemic Index foods produce greater satiety than high Glycemic Index foods.  This means that fewer Kj need to be eaten to obtain the same feeling of fullness.  In obese (as measured by the Body Mass Index) people, many of whom have exaggerated insulin secretion, a low Glycemic Index diet reduces the concentration of insulin in the blood after meals.  A low Glycemic Index diet will produce greater weight reduction than an equivalent low energy diet which was not designed to achieve a low insulin response.  Following a low Glycemic Index diet assists in lowering blood lipids as well as body weight.

Diabetes - in diabetic diets the current diet can be improved by replacing high Glycemic Index foods with low Glycemic Index foods (that is, foods listed as having a Glycemic Index of 50 or below are ideal for  diabetics.

Sport

The Glycemic Index can be used to manipulate blood glucose levels and muscle glycogen storage.  This is significant during the acute phase of exercise, immediately before, during and after performance.

Important Note:  Some foods have a low Glycemic Index but are nevertheless high in fact and/or salt and are therefore not appropriate choices! (eg. peanuts).

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