"Don’t eat that bread or potato because they are fattening!"

How many of you have heard that statement before? In actual fact, proven scientific research now shows that bread and many other carbohydrate (CHO) containing foods are useful in attempting to lose weight as they reduce your appetite. The scientific research I am referring to is based on what is termed the ‘glycemic index’ (or GI).

The GI is a ranking of foods that tells us whether a food will raise blood glucose levels a lot or a little. CHO foods that break down quickly during digestion have a high GI (ie.> 70). The blood glucose response is fast and high. CHO foods that are digested slowly, release glucose gradually into the bloodstream have a low GI (ie.< 55). A medium GI food has a ranking of 56 -69.

The GI concept has benefits for many people. It can assist to control blood glucose levels in people with diabetes. I have already mentioned it can assist people who are trying to lose weight as there are ‘less hunger pangs’, contributing to less food intake with Low GI CHOs. It is also useful for athletes as low GI CHOs help to sustain endurance exercise for longer. The high GI CHOs have been shown to replenish the energy stores faster after the event.

There are many different factors that determine whether a food is going to have a high, medium or low GI. Some of these factors include how well cooked the CHO is or how much fat and protein a food contains. However, the only real way we can determine the GI of a food is through scientific testing. The GI is measured by feeding 50g CHO to a volunteer and then measuring the blood glucose response over the next 2-3 hours. The average value in 8-10 different volunteers becomes the GI of that food.

Now, getting back to that bread and potato. Low GI breads that are useful in weight loss and diabetes are those breads with ‘grainy bits’ such as ‘Burgen’ and ‘Vogel’ breads. Low GI potato includes sweet potato and new potato – two foods definitely not off the menu! For a comprehensive list of low, medium and high GI foods refer to ‘The New Glucose Revolution’ series of books by Prof Jennie Brand-Miller, Kaye Foster-Powell and Prof Stephen Colagiuri, published by Hodder Headline Australia.

To assist you to quickly identify the GI of a food when in the supermarket, more and more foods now have the ‘GI symbol’ on them. Look out for it when next shopping.

Carolyn Davis is an accredited practising dietitian at the Goonellabah Medical Centre. Phone 6625 0000 for an appointment.