The concept of the glycaemic index was first instigated by Dr. David Jenkins, a professor in nutrition at the University of Toronto, Canada in 1981. Initially it was used to help diabetics to control their blood sugar, but later its relevance to weight management and sporting performance became apparent.
The glycaemic index (GI) is a ranking of a food based on its immediate effect on blood sugar levels. All foods are compared to pure glucose, which has a GI of 100 and are tested in equivalent carbohydrate amounts. In other words, every food portion that is tested contains 50 grams of carbohydrate (Jelly Beans (60g) = 50g carbohydrate: White bread (100g) = 50g carbohydrate).