The glycemic index is a measuring system that categorizes carbohydrates based on their affect on your blood sugar levels. The idea behind a low glycemic index diet is that eating carbohydrates that help maintain steady blood sugar levels can lead to weight loss. Some popular commercial diets based on the glycemic index theory include the Zone diet and Nutrisystem.
Physiology
Although most carbohydrates are broken down into simple sugars in your body, your body responds to each type of carbohydrate differently. Some carbohydrates move through your digestive system quickly, thus entering your bloodstream quickly as well. These carbohydrates cause rapid increases in your blood sugar levels, as well as dramatic decreases. Other types of carbohydrates move through your digestive system slowly, entering your bloodstream at a slower rate. This carbohydrates raise blood sugar levels, but at a steadier rate. The presence of sugar in your bloodstream signals your pancreas to release insulin, the hormone responsible for bringing glucose to your cells. The higher your blood sugar levels become, the more insulin your pancreas releases.
Theory
The theory behind a glycemic index is that chronic high blood sugar levels or constant increases and decreases in blood sugar eventually lead to a condition called insulin resistance. If your cells become resistant to insulin, they do not respond well to the hormone and thus blood sugar levels remain abnormally high. Insulin resistance is associated with obesity, type 2 diabetes, high blood pressure, heart disease and stroke.
Glycemic Index
The glycemic index is a scale from 0 to 100 that ranks carbohydrates based on their affect on your blood sugar level. Each carbohydrate is compared to glucose, which has a glycemic index of 100, and then assigned a number. Carbohydrates that are assigned a number from 70 to 100 are considered high glycemic index. You should avoid these foods as much as possible on a low glycemic index diet. Foods ranked between 56 and 69 are categorized as medium glycemic index. You should consume these foods sparingly. Foods assigned a number of 55 or below are considered low glycemic index and should supply the basis of the low glycemic index diet.
Food Examples
MayoClinic.com provides some basic food recommendations for following a low glycemic index diet. Focus on oats, barley and bran cereals, rather than cereals that contain white flour or added sugar. Choose whole grain breads or sourdough breads over white breads. Incorporate lots of vegetables and moderate amounts of fruit into your diet. Reduce your intake of pasta, rice and potatoes, especially white varieties.
