The concept of giving a carbohydrate food a Glycemic Index (GI) was developed by Dr. David J. Jenkins and colleagues in 1980–1981 at the University of Toronto in their research to find out which foods were best for people with diabetes. The glycemic Index uses a scale of 0 to 100, with higher values given to foods that cause the most rapid rise in blood sugar. Pure glucose serves as a reference point, and is given a Glycemic Index of 100.
Not all carbohydrate foods (“carbs”) release their sugar into the bloodstream at the same rate. The glycemic index is used as a way to gauge how quickly a particular food will cause your blood sugar level to rise. A rapid rise in blood sugar causes rapid insulin release and resultant metabolic pathology. Eating low GI carbohydrates will not cause a rapid rise in blood sugar and insulin levels and prevent the metabolic problems that go along with this such as diabetes, cardiovascular disease, cholesterol-lipid abnormalities and weight gain. Researchers has shown that high glycemic index foods generally make blood sugar levels higher. In addition, people who eat a lot of high glycemic index foods tend to have greater levels of body fat, as measured by the body mass index (BMI). High BMIs are linked to obesity, heart disease, and diabetes. Go to an excellent GI database from the University of Sydney.
Switching to eating mainly low GI carbs that slowly release glucose into your blood stream keeps your energy levels balanced and you will feel fuller for a longer period of time between meals. Unless you have the type of personality that likes numbers and being real specific, don’t drive yourself crazy trying to look up every glycemic index every time you eat. For most people this is not a lasting way to make a dietary lifestyle change. Certain groups of foods have low GI and certain foods have high GI. Try to make up the bulk of your meal with low GI foods. You may effectively mitigate the GI of foods by including some fat, protein and/or soluble dietary fiber into your meal. These foods slow the rate at which your stomach will empty, thereby lowering the rate at which sugar is released into the bloodstream. Eating a salad before a bowl of pasta is an example of this approach. Using olive oil in the salad and/or tomato sauce will also produce this GI lowering effect.
Eating a couple of twinkies for lunch on the fly because you need a quick pick-me-up to get you through the afternoon puts your body into metabolic disarray. This high GI, carb only, fast food approach is playing a big part in America’s obesity and diabetes epidemics.