Glycemic Index and Load

When eating a healthy diet it is important to know what exactly your body is doing with the food you eat. So back to biology 101...


Your body gets energy to function by the food that we eat. Most of the food we eat is broken down into glucose at digestion, however some of it must first be converted in the liver before glucose is released into the bloodstream. Once in the blood stream the glucose goes into cells where its further broken down by glycolysis, the Krebs cycle, and the electron transport chain and turned into ATP, the body's usable energy. However there is a "maximum capacity" for ATP. The body only makes as much as it needs for whatever task you are doing at the moment. The rest is stored in muscles as glycogen or as fat. Because the body can store much more fat than glycogen, fat is about 80% of stored energy.

Obviously we would like to try to avoid fat storage, that is where knowing what your body needs is so important. First you need to know how many calories your body needs (check out my previous post about caloric needs here). Second you need to maintain a sustained source of energy that keeps blood sugar levels stable. This is where the glycemic index and glycemic load come in.

The glcemic index is a measure of how fast a particular food will raise blood sugars. As carbohydrates are the main factor contributing to blood glucose levels another measurement is important to look at. The glycemic load measures the carbohydrate content of a food along with the glycemic index to predict the blood sugar raising potential.  Simple carbs like candy have a high glycemic index and glycemic load because it is broken down into glucose very quickly and causes spikes in blood sugar levels. Complex carbs like vegetables take much longer to digest, therefore have a sustained release of glucose into the blood stream and no spike. The slow release allows your body time to use existing ATP and then convert the available glucose into more ATP, thus avoiding fat storage. So in conclusion, it is wise to avoid foods with a high glycemic index or load and to consume foods with lower levels. Check out this chart with a list of foods and their levels and the graph below to learn which foods are which.