A food's glycemic index (GI) is the amount that the level of your blood sugar, or glucose, rises compared to a value of 100 for either pure glucose--sugar--or white bread. The glycemic load (GL) estimates the effect that a food will have on your blood sugar, and you can calculate the GL by multiplying the GI by the number of grams of carbohydrates and dividing by 100. Since the GL considers both the GI and the amount of carbohydrates, it is a useful tool for controlling your blood sugar through diet by choosing certain foods.
Fat and Protein
The way to calculate GL is to multiply the number of carbohydrates per serving by the GI of the food. Unlike carbohydrates, protein and fat do not contribute to the glycemic load of a food. Foods that are carbohydrate free but high in protein or fat have a negligible glycemic load. Low GL protein sources include meats such as beef and pork, poultry such as chicken and turkey, and seafood such as fish and shellfish. Sources of fat that are low GL diet foods are oils, shortening, butter and high fat cheese.
Fruits and Vegetables
Some fruits and vegetables are low GL diet foods, while others have a higher GL. Non starchy vegetables such as broccoli, lettuce, cucumbers and eggplant have almost no carbohydrates, and no GL. Root vegetables such as carrots are higher in starchy carbohydrates. This increases the GI, but since the total number of carbohydrates in each serving is low, the GL is low. Starchy vegetables such as potatoes and sweet potatoes are not low GL diet foods. Many fruits are low GL despite being high GI because of their low total carbohydrates and high fiber per serving. Fruits on a low GL diet list include apples, pears, peaches and grapefruit.
Grains and Legumes
Whole grains and legumes are low GL diet foods. They have complex carbohydrates, including fiber, which means they have less of an effect on blood sugar than the simple carbohydrates from glucose or white bread. Whole grains for a low GL diet include whole grain breads, oatmeal and high fiber whole grain cereals. In addition to fiber, legumes have protein. Legumes that are low GL diet foods include garbanzo, butter, pinto and kidney beans. Peanuts have fiber, fat and protein, and have almost no GL, which makes them good for a low GL diet.
References
- National Cancer Institute: Diet History Questionnaire: Development of the DHQ Nutrient Database
- Mendosa.com: Revised International Table of Glycemic Index (GI) and Glycemic Load (GL) Values-2008
- USDA National Nutrient Database for Standard Reference, Release 22: Carbohydrate, by Difference (g)
- Harvard: Health: Glycemic Index and Glycemic Load for 100 Foods
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