Glycemic Index and Glycemic Load


Glycemic load gl formula and an apple.

Glycemic index and glycemic load are important factors that diabetic patients and patients with risk of having diabetes should apply in their daily selection of carbohydrate food. Food with a lower glycemic index is a good choice. Glycemic index is a number from 0 to 100 assigned to food, with reference to pure glucose, ( given the value of 100 ) which represents the relative rise in the blood glucose level two hours after taking that food. It rates carbohydrates according to how quickly they are broken down and release glucose during digestion.


Food with low Glycemic Index breakdown slowly and release glucose gradually while food with high Glycemic Index breakdown fast and release glucose quickly

The Glycemic index is useful for quantifying the relative rapidity with which the body breakdown carbohydrates. Individual responses vary greatly. GI diet or slow carb diet also helps in losing extra body weight. Low GI food decreases appetite too because of its slow breakdown and prolonged digestion.

GI values are calculated after research on carbohydrates. They are generally divided into three categories:

  • Low Glycemic Index: less than 55
  • Medium Glycemic index: 56-69
  • High Glycemic index: 70 and higher

Low Glycemic index food e.g. soy products, beans, fruits, milk, pasta, grain bread, oats, and lentils.

Medium Glycemic index food e.g. Orange juice, honey, brown rice, and wholemeal bread.

High Glycemic index food e.g. Potatoes and white bread.

Comparing GI values helps in making healthier food choices.


One drawback is that values do not relate to serving quantity. Food with a low glycemic index can have a high carbohydrate content. For example, a watermelon has a GI value of 80, but a typical serving is much smaller. To account for this glycemic load is calculated, that is the glycemic index of a typical serving. For example, a 120 g or 3/4th cup of watermelon has a GL value of 5.

Glycemic load

Glycemic load ( GL) takes into account the number of carbohydrates in a portion of food together with how quickly it raises blood glucose levels. It helps to work out how different sized portions of different food compare with each other in terms of their blood glucose-raising effect. For example, even though pasta has a low GI, a large serving still makes blood sugar high.


The glycemic load can be calculated by a formula:

GL = GI × g of Carbohydrate per serving /100

For example, the GI of wheat pasta is 43. The carbohydrate content of a standard 180g serving is 44 g.

So GL = 43 × 44 ÷ 100 = 19g

The GL values are grouped into:

  • Low Glycemic Load: 1-10
  • Medium Glycemic Load: 11-19
  • High Glycemic Load: 20 or more

The GL value of any food is affected by several factors, such as how food is cooked or processed. Secondly, it does not tell other food nutritional information. For example, whole milk has a GL value of 4 but it has fat too so not a very good choice for losing weight. Knowing the glycemic load is a helpful tool for planning meals. The Glycemic Index Foundation recommends keeping your daily glycemic load less than100 for optimal health.


Foods with a low glycemic load of 10 or less

  • 8 oz skimmed milk ( GL- 4)
  • 1/4 cup peanuts (GL-1)
  • 2 cups watermelon (GL-4. 3)
  • 1 cup kidney beans (GL-7)
  • 1cup bran cereal (GL-9)

Food with a medium Glycemic load of 11-19

  • One large banana. (GL-12. 4)
  • 1cup cooked oatmeal GL-11.7)
  • 1 medium doughnut (GL-17)
  • One cup of boiled brown rice (GL-18)
  • 1 tablespoon of honey (GL-11.9)

Food with a high glycemic load of 20 or more

  • 1 cup cornflakes (GL-21)
  • 2tablespoon of raisin (GL-27. 3)
  • 1 medium baked russet potato (GL-23)

Carbohydrates in grams are given on the Nutrition Facts label on packaged food. Divide the weight of food in grams by 100 then multiply by the carb per 100g. This will give the amount of carb. Consuming carbohydrates with low GI and calculating the number of grams of carbohydrates would produce the most stable blood sugar. It is useful for diabetic people to assess which quantities of which food are likely to be suitable for maintaining good blood glucose levels. Assessing the glycemic load of a food can be particularly helpful if you have a specific meal quite often or you want to try another meal but are not sure how it will affect your blood sugar level.

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