The glycemic index, GI, ranks foods on a scale of 1 to 100 according to how quickly they can raise your blood sugar level. The lower a carbohydrate scores on the glycemic index, the slower it becomes glucose in your body, and the less impact it has on blood-sugar levels. Originally developed as a tool for diabetics to help them choose carbohydrates that would keep glucose levels stable, low-GI foods can also help reduce cholesterol and lower your risk of heart disease. Several popular diets, including the Zone and South Beach diets, are based on choosing foods low on the glycemic index scale.
Step 1
Access the Sydney University Glycemic Index Research Service website -- the official site of the glycemic index. Testing food for the glycemic index is a scientific process that cannot be done at home. A group of test subjects are fed 50 g of the food being tested; then their blood sugar levels are checked at timed intervals. At another time, the same people are fed 50 g of pure glucose, and the timed blood sugar tests are repeated. The results are compared and averaged to assign a glycemic index score to the test food.
Step 2
Look for foods low in sugar but high in fiber or protein. Fiber and protein slow the absorption of glucose into your bloodstream. Whole grains are more likely to score lower on the GI than refined grains. Vegetables and fruits usually score lower than processed packaged foods. Only foods that contain some carbohydrates can be tested, because only carbs raise your blood sugar. Most meats will not have a GI score; although dairy products that contain lactose, a natural sugar, will have a GI score.
Step 3
Don't rely solely on the glycemic index to choose foods. In addition to fiber and protein, fat also slows the absorption of sugar. Foods high in fat also tend to score lower on the GI. A paradox of the GI is that certain sweets, such as a Snickers bar or Peanut M&Ms, are low-GI foods because of their high fat content. A Snickers bar actually ranks lower than an orange on the GI.
Although the GI can be a useful tool, it's important to consider the nutrients a food offers as well.
Tips and Warnings
- According to the "American Journal of Clinical Nutrition," following a low-GI diet can stabilize blood sugar levels, reduce "bad" low-density lipoprotein cholesterol levels, increase "good" high-density lipoprotein cholesterol levels and may reduce your risk of developing diabetes, cardiovascular disease and certain types of cancer.
- Some high-GI foods, such as watermelon or pineapple, may be OK to include in your diet occasionally. Always consult your physician before beginning any diet plan.
