Glycemic Index or GI is a measure of the effect of the carbohydrates in foods on blood-glucose levels. Carbohydrates that break down quickly in the process of digestion have high GI values, while carbohydrates that break down slowly have low GI values.
The concept of glycemic index is so important as it is helpful to the many people that struggle with diabetes and metabolic syndrome, also known as pre-diabetes. Not knowing how to eat for balanced blood sugar is an underlying cause in most diseases that plague Americans. Anyone can benefit by eating a low glycemic diet – especially those with high cholesterol, high blood pressure, heart disease, diabetes, excess weight and many other conditions.
The glycemic index rates specific foods using the effect of pure glucose on blood sugar as the reference point – with pure glucose being 100 percent. High GI foods have a GI of 70 or greater. Intermediate GI foods have GI’s of 56 to 69 and low GI foods have a GI of less than 55.
Examples of high GI foods include candy bars, sodas, many breakfast cereals such as corn flakes and Cheerios, sweet treats made with white flour, etc. Examples of low GI foods include less refined foods such as old fashioned oatmeal, All Bran cereal, beans, lentils, pumpernickel bread, Ezekiel bread, stone ground grains, apples, and plain yogurt.
Glycemic index is important because it helps to predict the blood glucose response to expect from eating particular foods. Being able to predictably lower blood glucose levels with food helps those with diabetes or glucose intolerance. It is also a great tool for weight loss as seen in diets such as Sugar Busters and Carbohydrate Lovers.
There are several defining qualities of particular carbohydrates that seem to influence the GI. One of these is called physical entrapment. This refers to a fibrous coating typically around a grain or legume that acts as a physical barrier and slows access to the starch inside. Examples of these are grains such as barley, grainy breads and legumes.
Particle size is another factor influencing GI. Smaller particles make the food easier to digest and therefore, the GI higher. An example is finely milled flour which is high GI.
Soluble fiber also influences GI by slowing down digestion, making the GI value low. Good examples of foods with soluble fiber include rolled oats, beans, lentils, and apples.
Acids foods are another factor in GI. Acid in foods slows down the rate starch will digest. Things like vinegar, lemon juice and pickled vegetables will lower GI by slowing down starch digestion.
Another big factor is the amount of water the starch contains. Raw starch is hard and granular and difficult to digest. When starch is cooked, the combination of water and heat expand and soften the starch molecules making them easier to digest. Using potatoes as an example – the GI index of the raw potato is lower than that of mashed potatoes which are high GI.
Combinations of grains with sugar actually make the starch more difficult to access. This makes cookies tend to have intermediate GI values especially those made with low GI grains such as oatmeal.
There is lots of information available on glycemic index – get your list, eat low GI for 4 weeks and see what happens.