Diet Information
|
Glycemic Load Compared to Glycemic Index (GI)Glycemic Index (GI) should not be confused with Glycemic Load (GL). Glycemic index (GI) measures the glycemic response of a standard amount (50g) of useable carbohydrate in a particular food. This is useful but not very precise, since the percentage of carbohydrate in the food may be low, medium or high. By comparison, glycemic load (GL) ranks foods according to the glycemic response of a regular serving of the food in question. For example, GL tells us the likely effect on blood sugar of eating a standard serving of carrots. So GL is really "GI-per-food-serving". Glycemic Index Measurement Based on 50 Grams of Useable CarbsThe glycemic index (GI) of a food portrays how rapidly that food raises blood sugar levels. But glycemic index tests are not based on commonly consumed portion-sizes of foods. Instead, GI tests are based on giving volunteers a portion size sufficient to contain 50g of useable carbs. Therefore the portion size of each GI-tested food will vary according to how much carbohydrate it contains. For example, carrots contain only about 7 percent carbs, so the portion of carrots eaten by the volunteer will be huge - about 1.5 pounds. Serving sizes of foods (like bread) which contain a higher percentage of carbs, will be much smaller. Glycemic Load (GI Rating Per Regular
Food Portion) For Sample Foods The Drawback of the Glycemic IndexAs explained above, glycemic index tests are not performed on typical portion sizes. So in practice, by using the Glycemic Index alone, the glycemic effects of foods containing a small percentage of carbs are likely to be overstated, while the glycemic effects of foods containing a high percentage of carbs are likely to be understated. For example, foods that are mostly water or air will not cause a surge in your blood sugar levels even if their glycemic index is high. This is why scientists developed the idea of Glycemic Load. It ranks foods according to actual carb content (eg. in a typical portion-size), not how fast a 50g amount of carbs raises blood sugar levels. Glycemic Load - How is it MeasuredGlycemic load tells you how much carbohydrate is in the food, rather than just how high or how rapidly it raises blood sugar levels. To calculate glycemic load in a typical serving of food, divide the GI of that food by 100 and multiply this by the useable carbohydrate content (in grams) in the serving size. Glycemic Load ExampleAccording to some GI tests, carrots have a glycemic index of 49. They contain about 7 grams of carbohydrate per 100g of carrots. So to calculate the glycemic load for a standard 2oz (about 50g) serving of carrots, divide 49 by 100 (0.49) and multiply by 3.5. The glycemic load (GL) of carrots is therefore 1.7. In some GI tests, carrots score as high as 95 for glycemic index. Even so, the glycemic load for a 50g serving size of carrots is still only 3.3. Related Glycemic Index LinksGlycemic
Index |