What is the Glycaemic Index?
The Glycaemic Index (GI) measures the rate at which carbohydrates are broken down into glucose and enter the bloodstream. Measured on a scale of 1-100, the GI categorizes carbohydrates into high GI, medium GI or low GI. Carbohydrates that are broken down quickly during digestion and release glucose rapidly into the bloodstream carry a high GI value of 70 and over, whereas carbohydrates that are broken down slowly during digestion and release glucose steadily into the bloodstream have low GI values of 55 or less.
An important factor to consider is whilst the GI tells you how quickly carbohydrates are broken down and released in the body, it only relates to these carbohydrates that are consumed on their own. However, most carbohydrates are consumed with a variety of other foods, and this can influence the overall GI of a meal. The GI can help you to lower the overall GI of a meal by including more low GI foods. Choosing meals with an overall low GI means a steadier and gradual release of glucose over a longer period of time, helping to maintain a sense of fullness, minimize low blood sugar levels, sustain your energy levels and optimise your body’s sensitivity to insulin. Low GI foods may also make you feel ‘fuller’, because they remain the stomach for longer.
While the Glycaemic Index is an important measure, the Glycaemic Load (GL) is actually more significant because it provides a measure of the total glycaemic response to a food or a meal. It is calculated using the Glycaemic Index of the food (GI) expressed as a percentage, multiplied by the grams of carbohydrate per serving. 1 GL unit is approximately equal to the glycaemic effect of 1g of glucose.
A typical diet has approximately 100 GL units per day (ranging from 60 to 180)
The Glycaemic Load Range is shown as;
Low GL = 10 or less
Medium GL = 11-19
High GL = 20 or more
However, both the origin of the food and its method of preparation can have a significant effect on both its GI and GL.
Samples of 150g of plain boiled white rice from different countries all contained 42g of carbohydrate by their GI (normally 70) ranged from 45 to 69 - and their Glycaemic Load ranged from 18.9 to 29! (That’s from 18.9 to 29g of glucose!)
SMC1838 DA5119
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