The Gylcemic Index Decoded

The glycemic index is a way of rating a food's effect on blood sugar. It measures the rate that glucose from food is absorbed into the blood stream. The slower the glucose is absorbed the lower the GI rating of the food. Conversely, the faster the glucose from the food is absorbed the higher the GI rating.

Health wise, a slow release of blood sugar is preferable. During the digestion process, glucose along with other sugars is released. To regulate blood sugar to normal levels, the body responds by releasing insulin, which amount other functions, releases the hormone insulin. Insulin allows the glucose to be stored for later use. Continual sharp rises/falls in blood sugar can lead to the development in diabetes so maintaining a low GI diet can help reduce the risk of developing the disease. 

A low GI diet is also useful for those watching their weight as it can help reduce hunger and it also has a beneficial effect on blood lipid profiles (which will help keep your heart healthy).

A low GI diet can also help improve energy levels through the slow and steady release of blood sugar. In contrast, high GI foods such as lollies or white bread cause a rapid increase in blood sugar, followed by an equally rapid decrease that can leave you feeling tired and lethargic.

These facts often lead people to think that the GI of a food rates how healthy it is. This is not the case and GI cannot be used alone to rate the healthiness of a food. Some high GI foods such as watermelon, bananas and potatoes contain valuable nutrients and make an important contribution to a healthy diet.

On the other hand, some low GI foods such as chocolate and chippies are high in empty calories and should only be eaten in moderation. The GI value of foods is useful if you are eating them alone but a lot of the time, foods are eaten in combination with others, so it pays to look at the overall GI of our meals and diet.

There are various factors that affect the GI rating of a food including the presence of fat, protein and fibre which all act to lower the GI value of food. If you were eating a meal of potato (high GI), meat (low GI) and green vegetables (low GI), your meal would move towards the low GI spectrum rather than the high GI because of the protein, fat and fibre in the meal.

One more point to consider is the portion of food and the actual amount of carbohydrate in the food. Although watermelon is high GI – because there is little carbohydrate in the watermelon it is effects on blood sugar and the following insulin response are not significant.

Also eating small amounts of high GI carbohydrate foods is unlikely to have a big impact on blood glucose and insulin levels. Conversely, eating a large quantity of relatively low GI carbohydrates such as muesli or wholegrain bread — can still raise blood glucose and insulin levels.

A good way to help make your diet low GI is to find replacements for common high GI foods. Below are some ideas:
 

White rice - swap for basmati rice

White bread - swap for whoelgrain bread

Cornflakes - swap for bran flakes

Boiled potatoes - swap for baked potatoes (fibre in the skin lowers their GI value!