Learn the truth about the glycemic index

Despite the growing popularity of the glycemic index as a tool to help people improve their health, there are still many controversies and misconceptions surrounding it. We'll give you the facts about this food classification system.

• The glycemic index (GI) is a classification of carbohydrate foods according to the effect they have on blood sugar levels.
• Regulating blood sugars is a key strategy in preventing and controlling certain diseases, particularly diabetes.
• Over 20 years ago, researchers at the University of Toronto studied more than 50 carbohydrate-rich foods and their effect on blood glucose. The glycemic index was developed by measuring how much a person's blood glucose increased two to three hours after eating a carbohydrate-rich food compared to a reference food, which was either pure glucose or white bread. A food that is digested and absorbed quickly has a high GI value, causing a rapid increase in blood sugar. A food that is digested and absorbed slowly has a low GI value.
• Foods can have a low GI (less than 55), an intermediate GI (55–70), or a high GI (higher than 70). There are currently more than 750 published GI values of various foods.

• We used to believe that foods high in sugar, such as cakes, cookies, chocolate, and fruit, were harmful for diabetics because they were quickly digested, leading to a rapid rise in blood sugar. But some sugars actually have a lower glycemic index than many more starchy foods. Therefore, many high-sugar foods in moderate servings have no greater effect on blood glucose than many starchy foods and can be included as part of a diabetic meal plan.
• Researchers are learning that a low-GI diet may help lower the risk of developing diabetes and heart disease in healthy people.
• In sports medicine, high-GI foods have been used as a source of quick energy, while low-GI foods have been used in endurance sports.
• There's an interesting theory that low-GI foods can aid in weight loss because they help to control insulin levels. The hormone insulin promotes the storage of fat and also inhibits the breakdown of stored fat for energy.

• One of the biggest issues is that many foods that are considered healthy choices have a higher GI than foods that are considered to be less nutritionally desirable. For example, mashed potatoes have a higher GI than table sugar, and it's definitely confusing to find that unrefined wholewheat bread has almost the same GI as white bread.
• You should also consider the effect of glycemic load (GL). It assesses the effect of carbohydrate foods on blood sugar by taking into account the GI, but it gives a fuller picture than the GI alone. The GI tells you how rapidly a particular carbohydrate turns into sugar, but it doesn't tell you how much of that carbohydrate is in the food. Be sure to consider both the GI and GL of foods you eat.

A low-GI diet will include many foods recommended for a healthy diet like fruits and vegetables, whole grains, and legumes. These foods are lower in fat, high in fibre and are a rich source of vitamins, minerals, and antioxidants. With further research, the glycemic index may become an easier tool to use when choosing foods. In the meantime, the general principles of a healthy diet (variety, balance, and moderation) still apply.