My friend Dr. Gabe Mirkin recently wrote a very interesting piece on the importance of the Glycemic Load. My comments are in italics:
When you eat a food, your blood sugar level rises. The food that raises blood sugar the highest is pure table sugar. Glycemic index is a ratio of how high a particular food raises blood sugar in comparison to how high table sugar raises blood sugar levels. Foods whose carbohydrates break down slowly release glucose into the bloodstream slowly, so blood sugar levels do not rise high and therefore these foods have low glycemic index scores. Those that break down quickly cause a high rise in blood sugar and have a high glycemic index. (High blood sugar is undesireable because it causes the over-production of insulin, a powerful fat storing hormone. High insulin stops the fat burning process during dieting, and unchecked can cause health problems.)
Most beans, whole grains and non-starchy vegetables have low glycemic index; while sugars, refined grains made from flour, fruits and root vegetables have a high glycemic index.
If you try to use glycemic index tables to guide your choice of foods, you will see things that should bother an intelligent person. A carrot has almost the same glycemic index as sugar. That is ridiculous. You know that a carrot is a far wiser choice for dieters or diabetics than table sugar. (Carrots contain bulk and fiber that causes the natural sugar to be absorbed more slowly.)
To deal with this conflict, researchers developed a new measure to rank foods called Glycemic Load (GL). To calculate glycemic load, the grams of carbohydrate in a serving of food are multiplied by that food’s glycemic index.
Carrots and potatoes both have a high glycemic index, but using the GL index, carrots dropped from high GI of 131 to a GL of 10. Potatoes fall from a GI of 121 to a GL of 45. Air-popped popcorn, with a glycemic index of 79, has a GL of 4.
Foods that are mostly water or air will not cause a steep rise in your blood sugar even if their glycemic index is high. That’s why Glycemic Load is more useful. However, all of these tools should be used for research and not for your daily selection of foods. Use your own common sense and eat plenty of fruits, vegetables, whole grains, beans and other seeds. If you are diabetic, you can eat root vegetables and fruits with other foods to slow the rise in blood sugar they may cause. (Another way to slow down the breakdown of food into blood sugar is to combine foods. For example, those same carrots, when eaten with a protein source such as a chicken breast, and a complex carbohydrate such as a sweet potato, will break down much more slowly over period of hours, than when ingested alone. That’s why it is important to eat carbs with protein, and even a little healthy fat (fish or flax oil, nuts, avocados, etc) , when possible. To make it easy to meet all of your protein needs, you can rely on a high quality protein drink such as Labrada’s Lean Body Ready to Drink shakes and meal replacements. Lee)
Recommended reading: Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating (Simon & Schuster, June 2001), by Harvard School of Public Health professor and researcher Walter Willett, M.D.