What Is Glycemic Index (GI)?

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What is glycemic index?The concept of Glycemic Index or GI was developed by Dr. David D. Jenkins and colleagues in 1980–1981 at the University of Toronto in their research to find out which foods were best for people with diabetes (1). It is a numerical way of describing how carbohydrates in foods affect blood sugar levels. The index measures how quickly a 50-gram serving of a particular food converts to sugar (2).

GI measures the effect of food on blood – sugar levels. Foods with a high glycemic index cause a faster and higher rise in blood-sugar, whereas foods with a low glycemic index cause a slower rise in blood-sugar.

Glycemic Index is a useful tool to describe the effects of different carbohydrates on blood sugar levels (3). Usually, food with low GI is considered to be more healthy than food with high GI.

Diets that emphasize low-GI-foods decrease the risk of developing type 2 diabetes and improve blood sugar control in those already afflicted (4).

Diet with low GI are associated with higher level of HDL-cholesterol (the good cholesterol) and with reduced incidence of heart attack (5).

Studies also indicate that the effectiveness of low-fat, high carbohydrates diets for weight loss can be improved by reducing GI (6).

Glycemic Index (GI) of different foods

High: baked potatoes 85, corn flakes 81, waffles 76, donuts 76, potato chips 75, raisins 64, ice cream 61.

Medium: pineapple 59, oatmeal 58, cooked potatoes 56, mango 56, white rice 56, popcorn 55, sweet potatoes  54, sweet corn 53, kiwi 53, bananas 52, green peas 48, carrots 47, macaroni 47, grape 46

Low: oranges 44, spaghetti 42, black eyed peas 42, apples 38, skim milk 32, dried apricots 31,lentils 29, barley 25, cucumber 15, broccoli 15, eggplant 15, pepper 15, tomatoes 15, spinach 15


  1. DJ Jenkins et al. (1981). “Glycemic index of foods: a physiological basis for carbohydrate exchange.” Am J Clin Nutr 34; 362–366.
  2. Insel P, Ross D, McMahon, Bernstein M. Nutrition, Fourth Edition, Jones and Bartlett Publishers 2011, p. 162 – 163.
  3. Foster-Powell K, Holt SHA, Brand-Miller JC. International table of glycemic index and glycemic load values:2002 Am J Clin Nutr.2002;76:5-56.
  4. Willet W, Manson J, Liu S. Glycemic Index, glycemic load, and risk of type 2 diabetes. Am J Clin Nutr 2002;76(suppl):267S-280S.
  5. Leeds AR. Glycemic index and heart disease. Am J Clin Nutr 2002;76(suppl)286S-289S.
  6. Pawlak DB, Ebbeling CB, Ludwig DS. Should obese patients be counseled to follow a low-glycemic index diet? Yes. Obes Rev 2002;3:235-243.