Glycemic Index vs. Glycemic Load

Manyof us have heard of the Glycemic Index. For those who are new to theterminology, Glycemic Index (GI) is a rating system which estimates howquickly glucose from foods that we eat can enter our bloodstream.  Theyset a standard measure - how quickly will 50 grams of the particularfood's carbohydrates turn to sugar. (For comparison, glucose is given aGI rating of 100.) Simply put, the closer the GI rating is to 100, thefaster food goes into your blood. This is important for us to knowbecause high blood sugar causes insulin to be secreted by the pancreasand stores the excess glucose as fat. So by keeping your insulin levelssteady you can help maintain or lose excess weight. Publications areavailable with the GI ranking of particular food types. One of the mostcomprehensive is at http://www.mendosa.com/gilists.htm.

• High = GI of 70 or more
• Moderate = GI of 56 - 69
• Low = GI of 55 or less

What GI doesn't tell you is how many carbohydrates are in a serving.  Thispresents a problem. A carrot for example has a GI of 71. This may makeit seem that carrots would interfere with weight loss or even causeweight gain! This is where Glycemic Load may be a helpful measurement.Although the GI ranks how rapidly a particular food turns into sugar,the serving amount is not clear. The Glycemic Load (GL) is a ranking ofhow much a standard serving of food raises your blood sugar. The lowerthe GL, the less a serving of food will trigger your blood sugar tospike.

• High = GL of 20 or more
• Moderate = GL of 11 - 19
• Low = GL of 10 or less

Since a serving of carrots has 5.3 grams of carbohydrate, to get 50 grams, you'd

haveto eat about a pound and a half of them! GL takes the GI value andmultiplies it by the actual number of carbohydrates in a serving.  Divide that by 100 and you have Glycemic Load! (71 x 5.3 = 376.3 / 100 = 3.76)  Socarrots have a very low GL…and, they are packed with the antioxidantbeta-carotene. Talk about throwing the baby out with the bath water…

Theonly foods that should really be eaten sparingly are the ones with highratings in both GI and GL. Still, it is important to keep in mind thatcombining healthy fats (nuts, avocados, olive oil) and lean proteinwith even the moderate GI and GL foods will bring their overall ratingdown considerably. So you can still have fruit, just eat it with nuts!

William E. Hapworth M.D.