In recent years, GI — or Glycemic Index — has become a commonly used term. You hear about it on the radio, read about it in magazines and see snippets on TV. Many people are using the GI in their day-to-day life to try to lose weight, manage their diabetes, reduce the effects of polycystic ovary syndrome (PCOS) or simply have better energy throughout day.

The GI is a way of measuring the effect that foods containing carbohydrate have upon our blood sugar levels and therefore how our body is supplied with energy. Unfortunately, the GI alone doesn’t give a full picture of the overall effect of a foodstuff upon blood sugar levels because it doesn’t take into account the amount of carbohydrate in a meal — which is where the GL, or Glycemic Load, comes in.

The GL is a slightly newer scale than the GI and it provides a way of measuring the effect on blood sugar levels produced by a normal serving of the food.

It’s all about carbs

Carbohydrates are present in most of the foods we eat. Vegetables, fruit, dairy, nuts, seeds, lentils, chick peas, soy products, olives, avocado, pasta, bread, rice, couscous, cakes, biscuits, lollies, apple pie — all of these foods contain carbohydrates. In fact, the only foods that don’t contain carbohydrates are meat, fish and oils. Carbs also come in a variety of forms, most commonly sugars, fibres and starches.

Carbohydrates are important to us, as they are the primary source of energy for our bodies. They provide essential fuel to our brains and are the main source of fuel for our muscles. We use carbohydrate to fuel the functioning, movement and activity of our bodies. Every time a muscle contracts, every time your heart beats, every time you speak or smile or think about something, you’re using carbohydrates. So we all need them and we need them every day.

While this food group is an important part of a healthy diet, many people eat too much carbohydrate and this excess energy (kilojoules) can be converted to fat in the body. It’s also true that some carbohydrates are better for you than others.

Eating a diet too high in carbs and eating too many of the wrong kind can increase your risk of putting on weight, of becoming obese or developing diabetes.

Carbohydrate Digestion

Carbohydrates are the most widely consumed substance in the world, second only to water. Most cultures have carbohydrates as their staple foods, whether they be rice, corn in the form of polenta or maize, pasta, breads, potatoes or couscous. These are the foundation foods of the majority of the world’s population.

The basic building block of carbohydrate is a sugar molecule, which is a simple combination of carbon, hydrogen and oxygen atoms. Starches and fibres are made up of chains of sugar molecules, bound together in different ways and different combinations, with some carbohydrates containing hundreds of sugar molecules.

For us to make use of carbohydrate from the foods we eat, it first has to be broken down into a form that can be absorbed and used by our cells. This process of digestion and absorption takes the long chains of carbohydrate and breaks them down into glucose, a single sugar molecule small enough to cross into the bloodstream and be utilised by the body.

This digestive process starts in the mouth, where enzymes in saliva start breaking down starch molecules. Digestion and absorption are continued in the small intestines, where enzymes produced by the pancreas work to break down the remaining carbohydrate, again into simple glucose molecules.