WHAT'S THE DIFFERENCE BETWEEN THE GLYCEMIC INDEX (GI) AND GLYCEMIC LOAD (GL)?
The Glycemic Index (GI) has been used for many years as guide to the rate at which carbohydrate content is absorbed into the blood stream for energy, and the effect it has on raising blood sugar levels. The Glycemic Index (GI) is a measure of the degree to which a carbohydrate is likely to raise your blood sugar (glucose) levels. The scale is 0 to 100 (based on either white bread or glucose), with 0 being low and 100 being high. The GI compares equal quantities of carbohydrates and provides a measure of carbohydrate quality but not quantity. So the drawback with GI ratings is that they are not based on commonly-consumed portion sizes of foods.
For example, only about 7% of a carrot is made up of are useable carbohydrates. But because a 50g carbohydrate content is employed as the standard measure for a GI rating of individual foods to show how fast blood sugar level are raised, a larger than normal food portion is used for the GI calculation. In the case of carrots, for example, the amount is equivalent to 1.5lbs - far more, of course, than people normally eat as a snack or part of a meal.
As a result, the GI rating often overstates relatively small carbohydrate content in a food item like a carrot.
The reverse is also true, i.e. the glycemic effects of foods containing a high percentage of carbs like bread, can often be understated under the GI system.
Therefore we recommend using the Glycemic Load index with calculations based upon realistic food portions. GL ranks food according to the effects of actual carbohydrate content in a standard serving size of food.
Glycemic Load (GL) index
In 1997, Harvard University scientists introduced the concept of Glycemic Load (GL). This measure gives a more accurate reflection of the blood sugar effects of a standard food portion. In short, the GL of a typical serving of food is the product of the amount of available carbohydrates in that serving and the glycemic index of that food.
In practical terms, the higher the GL of a food, the greater the expected rise in blood glucose and the greater the adverse insulin effects of the food. Foods with a GL of 10 or below would be presumed to be less detrimental to health, while those with a GL of 20 and above would have more detrimental effects. Long term consumption of foods with a high glycemic load appears to be linked to a greater risk of obesity, diabetes, and inflammation. These, it also now appears, may even have negative effects on the brain that we are only beginning to understand.
We have chosen to base our program on the glycemic load, as this is more reflective of the actual load of carbohydrates. Another reason to use Glycemic Load is that Glycemic Index can be deceptive for certain foods, especially those that contain added fructose (which is an unhealthy sugar for people with diabetes).
About Fructose
Fructose has become the most prevalent sweetener in the diet because it is sweeter than sucrose (common table sugar). It is often recommended because, on the Glycemic Index, it measures a paltry 32 (out of 100). This would put fructose among the items with a "low glycemic index."
But we’ve been fooled for years by fructose and its low Glycemic Index. It turns out that consuming fructose has a dark side for all organ systems. Scientists have found that eating fructose actually creates insulin resistance. Fructose also contributes to abnormal sugar-protein reactions called "glycation," which damages a large array of structural (ligaments, cartilage, muscle) and functional (enzymes, neurotransmitters) proteins throughout the body.
Source: This excerpt is with permission of Michael A. Schmidt, PhD and Frog Books, Ltd. Berkeley, CA
Glycemic Load of Common Foods
Food |
Serving Size (grams) |
Glycemic Load per Serving |
||
Bakery Products and Breads |
||||
Banana cake, made with sugar |
80 |
18 |
||
Banana cake, made without sugar |
80 |
16 |
||
Sponge cake, plain |
63 |
17 |
||
Vanilla cake, made from packet mix with vanilla frosting |
111 |
24 |
||
Apple pie, made with sugar |
60 |
13 |
||
Apple pie, made without sugar |
60 |
9 |
||
Waffles, Aunt Jemima |
35 |
10 |
||
Bagel, white, frozen, reheated |
70 |
25 |
||
Baquette, white, plain |
30 |
15 |
||
Coarse barley bread, 75% kernels |
30 |
7 |
||
Hamburger bun, white |
30 |
9 |
||
Kaiser roll |
30 |
12 |
||
Pumpernickel bread, Whole grain |
30 |
6 |
||
50% cracked wheat kernel bread |
30 |
12 |
||
White bread, wheat flour |
30 |
10 |
||
Wonder™, enriched white bread, wheat flour |
30 |
10 |
||
Whole-wheat bread |
30 |
9 |
||
100% Whole Grain™ bread (Natural Ovens) |
30 |
7 |
||
Pita bread, white |
30 |
10 |
||
Corn tortilla |
50 |
12 |
||
Wheat tortilla |
50 |
8 |
||
Beverages |
||||
Coca Cola® soda, average |
250 |
15 |
||
Fanta® orange soft drink |
250 |
23 |
||
Lucozade®, original (sparkling glucose energy drink) |
250 |
40 |
||
Apple juice, unsweetened, average |
250 |
12 |
||
Cranberry juice cocktail (Ocean Spray®) |
250 |
24 |
||
Grapefruit juice, unsweetened |
250 |
11 |
||
Orange juice, average |
250 |
13 |
||
Tomato juice, canned, no added sugar |
250 |
4 |
||
Breakfast Cereals and Related Products |
||||
All-Bran™, average |
30 |
4 |
||
Coco Pops™, average |
30 |
20 |
||
Cornflakes™, average |
30 |
21 |
||
Cream of Wheat™ (Nabisco) |
250 |
17 |
||
Cream of Wheat™ Instant (Nabisco) |
250 |
22 |
||
Grapenuts™, average |
30 |
15 |
||
Muesli, average |
30 |
16 |
||
Oatmeal, average |
250 |
13 |
||
Instant oatmeal, average |
250 |
17 |
||
Puffed Wheat, average |
30 |
16 |
||
Raisin Bran™, (Kellogg's) |
30 |
12 |
||
Special K™ (Kellogg's) |
30 |
14 |
||
Grains |
||||
Pearled barley, average |
150 |
11 |
||
Sweet corn on the cob, average |
150 |
17 |
||
Couscous, average |
150 |
23 |
||
White rice, average |
150 |
23 |
||
Quick cooking white basmati |
150 |
23 |
||
Brown rice, average |
150 |
18 |
||
White rice, converted (Uncle Ben's®) |
150 |
14 |
||
Whole wheat kernels, boiled |
50 |
14 |
||
Bulgur (cracked wheat), boiled |
150 |
12 |
||
Cookies and Crackers |
||||
Graham crackers |
25 |
14 |
||
Vanilla wafers |
25 |
14 |
||
Shortbread |
25 |
10 |
||
Rice cakes, puffed |
25 |
17 |
||
Rye crisps, average |
25 |
11 |
||
Soda crackers |
25 |
12 |
||
Dairy Products and Alternatives |
||||
Ice cream, regular |
50 |
8 |
||
Ice cream, premium |
50 |
4 |
||
Milk, full fat |
250 |
3 |
||
Milk, skim |
250 |
4 |
||
Reduced-fat yogurt with fruit, average |
200 |
7 |
||
Fruits |
||||
Apple, raw |
120 |
6 |
||
Banana, ripe (all yellow) |
120 |
13 |
||
Dates, dried |
60 |
42 |
||
Grapefruit |
120 |
3 |
||
Grapes, average |
120 |
8 |
||
Orange, average |
120 |
5 |
||
Peach, average |
120 |
5 |
||
Peach, canned in light syrup |
120 |
9 |
||
Pear, average |
120 |
4 |
||
Pear, canned in pear juice |
120 |
5 | ||
Prunes, pitted |
60 |
10 |
||
Raisins |
60 |
28 |
||
Watermelon |
120 |
4 |
||
Beans and Nuts |
||||
Baked beans, average |
150 |
7 |
||
Black-eyed peas, average |
150 |
13 |
||
Black beans |
150 |
7 |
||
Chickpeas, average |
150 |
8 |
||
Chickpeas, canned in brine |
150 |
9 |
||
Navy beans, average |
150 |
12 |
||
Kidney beans, average |
150 |
7 |
||
Lentils, boiled |
150 |
5 |
||
Soy beans, average |
150 |
1 | ||
Cashews, salted |
50 |
3 |
||
Peanuts, average |
50 |
1 |
||
Pasta and Noodles |
||||
Fettuccini, average |
180 |
18 |
||
Macaroni, average |
180 |
23 |
||
Macaroni and Cheese (Kraft) |
180 |
32 |
||
Spaghetti, white, boiled 5 minutes, average |
180 |
18 |
||
Spaghetti, white, boiled 20 minutes, average |
180 |
27 |
||
Spaghetti, wholemeal, boiled, average |
180 |
16 |
||
Snack Foods |
||||
Corn chips, plain, salted, average |
50 |
17 |
||
Fruit Roll-Ups® |
30 |
24 |
||
M&M's®, peanut |
30 |
6 |
||
Microwave popcorn, plain, average |
20 |
8 |
||
Potato chips, average |
50 |
11 |
||
Pretzels, oven-baked |
30 |
16 |
||
Snickers Bar® |
60 |
19 |
||
Vegetables |
||||
Green peas, average |
80 |
3 |
||
Carrots, average |
80 |
3 |
||
Parsnips |
80 |
12 |
||
Baked russet potato, average |
150 |
26 |
||
Boiled white potato, average |
150 |
14 |
||
Instant mashed potato, average |
150 |
17 |
||
Sweet potato, average |
150 |
17 |
||
Yam, average |
150 |
13 |
||
Miscellaneous |
||||
Hummus (chickpea salad dip) |
30 |
0 |
||
Chicken nuggets, frozen, reheated in microwave oven, 5 minutes |
100 |
7 |
||
Pizza, plain baked dough, served with Parmesan cheese and tomato sauce |
100 |
22 |
||
Pizza, Super Supreme (Pizza Hut) |
100 |
9 |
||
Honey, average |
25 |
10 |
* Compared with pure glucose, which is assigned a glycemic index of 100.
Sources: This table is adapted with permission from: "International tables of glycemic index and glycemic load values: 2002," by Kaye Foster-Powell, Susanna H.A. Holt, and Janette C. Brand-Miller in the July 2002 American Journal of Clinical Nutrition, vol. 62, pages 5-56. The complete list of the glycemic index and glycemic load for 750 foods can be found at: http://www.ajcn.org/cgi/content/full/76/1/5.
Updated (where applicable) with current values from the "Home of the Glycemic Index" - the official website for the glycemic index and international GI database which is based in the Human Nutrition Unit, School of Molecular and Microbial Biosciences, University of Sydney: (http://www.glycemicindex.com/). Last modified: December 13, 2005.