What is Glycemic Index?

Diabetes management calls for a major overhauling in the dietary practices of an individual. The most important nutrient to be modified is carbohydrate. Let us see how and in what way knowing GI of a particular food helps?

Carbohydrates are a class of foods which are known for their saccharide (sugar) content. A food containing carbohydrate which when digested and absorbed increases the glucose levels of blood. This increase in blood glucose has now become the key to planning diets for diabetics, obese and weight watchers. The term used to describe this increase in blood glucose is called as Glycemic Index (GI).

The concept of GI was developed by Dr. David J. Jenkins and his colleagues in 1980–81. Glycemic index consists of a scale from 1 to 100, indicating the rate at which 50 grams of Carbohydrate in a particular food is absorbed into blood. On this scale Glucose is used as the main reference point and is rated 100. A GI value of 70 and above indicates High Glycemic index, 56-69 medium and less than 55 indicates low GI. Simply put a food which does not lead to sharp increase in blood sugar post absorption is termed as a low GI food. Thus the foods which take time to digest and slowly get absorbed in blood have low GI and vice versa.

So if you are trying to manage your blood sugar or trying to lose weight select foods with Low Glycemic index as they will cause a slower rise in blood sugar. Foods with low glycemic index tend to have more fiber than the higher glycemic index foods. In other words, select dense wholegrain cereals, brown rice, whole wheat pasta, dalia, rather than refined or processed white bread, white rice and pasta.

Apart from knowing the GI value of foods there are other factors which can help us in managing our blood glucose in a better way. These include:

  1. Even distribution of carbohydrate over the day rather than loading a meal completely with carbs.
  2. Eating small frequent meals rather than 2-3 large meals.
  3. Various forms of carbohydrate affect blood glucose levels in different ways even though the carbohydrate content is the same. E.g., a) Physical form – solid, liquid: a liquid food is easier to digest and thus increases blood sugar suddenly. Solids taking more time in digesting and thus have a high GI. e.g. A fruit Vs fruit juice. b) Raw or Cooked: raw carbohydrate foods rather than cooked ones are more slowly absorbed. c) Whole-foods rather than processed foods, are more slowly absorbed.
  4. Some of the complex carbohydrates do behave more like simple sugars, with a quick release of glucose. Like potatoes and many breakfast cereals such as cornflakes all have a high GI.

Following is a Chart of few commonly consumed foods with their GI:

Food Product Glycemic Index
Wheat 48
Rice, brown 50
Rice, white 58
Vermicelli 35
Buckwheat (kuttu) 54
Kellogg’s Corn Flakes 92
Kellogg’s Special K 69
White bread 70
Carrot 47
Peas 48
Potato, baked 85
Potato, boiled 88
Pumpkin 75
Sweet Corn 60
Sweet Potato 61
Yam (Zimikand) 37
Broad Beans 79
Rajmah 28
Soy bean 18
Apple 38
Banana 51
Cherries 22
Grapes 46
Mango 51
Orange 58
Pear 38
Kiwi 53
Watermelon 72
Apple Juice 40
Coca Cola 63
Orange Juice 52
Peanuts 14
Popcorn 72
Honey 55
Table Sugar 68

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