Explaining Glycemic Index and Glycemic Load

The glycemic index (GI) is a number that indicates how quickly a particular food will raise the blood sugar.

The higher the number, the higher the blood sugar response. Not all of these foods taste “sweet.”  Even some complex carbohydrates are broken down quickly into sugar in the body, particularly potatoes or grains that have been ground into flour.

Foods with a high glycemic index signal the body to produce large amounts of insulin, a hormone that carries blood sugar into the cells to be used for energy or stored for later use. After eating high GI foods, large amounts of insulin may be released causing a rapid drop in blood sugar (called “reactive hypoglycemia”) that can lead to shakiness, “spaciness,” or fatigue several hours after eating, as well as an increase in appetite.

High glycemic index foods should be avoided by people who are trying to lose weight, people who have diabetes or may be at high risk for diabetes, and people who have “hypoglycemia” symptoms. If you have any of these conditions, try to avoid foods with a high glycemic index and emphasize foods with GI below 45.

A more sophisticated measure of the glycemic effects of foods is called “glycemic load.”

Glycemic load considers the actual amount of carbohydrates present in a typical serving of a food. A glycemic load number below 10 is considered low, 11-19 medium, and 20 or above is high. For example, while watermelon has a high glycemic index number of 72, its glycemic load number is only 7.21 because of the limited amount of carbs in a serving.

Some foods have low impact on the blood sugar despite their high glycemic index when they are eaten in normal portion sizes. Carrots, for instance, have a high glycemic index, but it takes 6.6 cups of carrots to deliver the same amount of carbohydrate that is found in 1 cup of cooked spaghetti. Since most people do not eat that many carrots at a sitting, carrots do not tend to have a big impact on blood sugar. The Glycemic Load takes the amount of carbs in a typical serving into account along with the glycemic index and can give a more balanced view of how eating typical servings of a particular food will affect blood sugar.

Some basic tips to keep the glycemic load of the diet down include:

  • Eat whole grains (i.e., where you can see the grains in your bowl, not where they have been ground into flour.) Limit processed grains.
  • Pass on the potatoes and bananas.
  • Bring on the beans. Beans are a great source of protein as well as a good source of slowly digested carbohydrates.

For more information, see http://www.mendosa.com/gi.htm or read The GI Diet by  Gallop or The New Glucose Revolution by Wolliver. Thanks to the Institute of Functional Medicine.

Glycemic Index and Glycemic Load of Certain Foods

Glycemic Index Carbs (grams per serving) Glycemic Load per serving
High 70 or more 20
Medium 50-69 11 to 19
Low 49 or less 10 or less
Fruits
Apple, 1 average 38 16 6
Banana, 1 whole, ripe 51 26.5 14
Orange, 1 whole 42 12 5
Raisins, ½ cup 64 44 28
Watermelon 72 6 4
Strawberries 40 152 3.6
Vegetables
Broccoli, ½ cup steamed 6 2 1
Carrots, 1 cup raw 47 6 3
Corn on the cob, 1 ear 53 29 15
Green beans, ½ cup 28 5 1
Baked potato, white 85 30.5 26
Spinach, ½ cup steamed 6 3.5 1
Sweet potato 61 28 17
Tomatoes, 1 cup raw 61 28 17
Grains
Bagel 72 89 33
Corn tortilla 70 24 7.7
Pumpernickel bread, 1 slice 41 26 4.5
White bread, 1 slice 70 25 8.4
Wheat bread 70 28 7.7
French bread, 1 slice 95 64 29.5
Whole wheat pita 57 64 17
Bran muffin 1 medium 60 113 30
Corn Bread 1 slice 110 60 30.8
Oatmeal 1 cup 58 234 12.8
Oatmeal, instant 1 cup 65 234 13.7
Corn Flakes 1 cup 92 28 21.1
Kellogg’s Special K 1 cup 69 31 14.5
Grape Nuts ½ cup 75 58 31.5
Cheerios 74 30 13.3
Coco Pops 77 20.2
Popcorn 1 cup 55 8 2.8
Rice white, 1 cup cooked 64 36 23
Rice brown, 1 cup cooked 55 33 18
Barley 25 10.6
Buckwheat 54 16
Quinoa 53 13
Legumes
Baked beans 1 cup 48 253 18.2
Chickpeas, boiled 1 cup 31 240 13.3
Kidney beans 1 cup 27 256 7
Lentils 1 cup 29 198 7
Soy beans 1 cup 20 172 1.4
Pinto beans 1 cup 39 171 11.7
Chana Dal 8 – 11 3.9 2.4
Beverages
Apple Juice 8 oz 40 30 12
Pepsi 8 oz 58 25 15
Tomato juice, ½ cup 38 10 4

 

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