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Article by Gabi Steenkamp
Gabi Steenkamp has been working as a registered dietician in South Africa for the past 35 years.  she is the author of 10 books using the Low GI theory for Sustained energy.


The glycemic index (GI) is a relatively new nutritional tool used to fine tune carbohydrate intake. It is a measure of the real physiological response to food, giving an indication of the rate of absorption of carbohydrates in foods.

Using this glycemic index information, one can easily differentiate between fast release, and slow release carbohydrates, which enables one to optimise ‘fuel’ levels in the body.

All foods that have a GI of 55 or less are slow release carbohydrates and classed as LOW GLYCAEMIC INDEX FOODS. They are the best choices in preventing a large rise in blood glucose levels.

The graph below shows the effect of high GI food on blood glucose levels. Blood glucose rapidly rises to a high peak (blood glucose surge) and then plummet down as quickly, causing a graph that looks much like a witches hat. Irritability, lack of concentration and aggression are a few of the consequences of rapidly falling blood glucose levels.

HighGI-graph

Using the glycemic index (GI) concept, those suffering from diabetes or low blood sugar (hypoglycaemia), slimmers, children with Attention Deficit Disorder and sportsmen, can all optimize their blood glucose control.

LowGI-graph

The graph above shows how low GI foods are digested and absorbed steadily over a period of  3 hours and keep blood glucose levels steady for this time.

The low GI foods are more satisfying and do not cause the release of as much insulin as high GI foods do. Therefore low GI foods also prevent the huge drop in blood glucose which occurs after the initial rapid rise in blood glucose levels after eating high GI foods.

This is of particular relevance to sportsmen and women, slimmers and those with diabetes. Eating mainly slow release (Low GI) carbohydrates before a sporting event, ensures good ‘fuel’ levels in the early stages of the event, as well as preventing the dreaded sports induced hypo’s afterwards. Re-fuelling with fast release (high GI) carbohydrate drinks, maximizes glycogen stores immediately afterwards, preventing exhaustion, hypo’s and resulting in better recovery after the event.

In diabetes optimum blood glucose control can easily be achieved if mostly slow release carbohydrates are eaten in the correct amounts.

And in slimmers, by preventing surges of blood glucose levels, by eating mostly low GI (slow release) carbohydrates, the stimulation of fat STORAGE is prevented. Insulin, the hormone that helps to clear glucose from the blood is also the hormone that stimulates the body to store fat. Thus the more fast release carbohydrates are eaten, the more fat is stored.