What is the Glycemic Index?

The glycemic index (or GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar (glucose) levels after eating. Foods with a high GI are those which are rapidly digested, absorbed and metabolised and result in marked fluctuations in blood sugar (glucose) levels. Low GI carbohydrates – the ones that produce smaller fluctuations in your blood glucose and insulin levels – is one of the secrets to long-term health, reducing your risk of type 2 diabetes and heart disease. It is also one of the keys to maintaining weight loss. Here is the evidence.

For diabetes: All of the evidence based recommendations for the management of diabetes from the major diabetes organisations around the world (the American Diabetes Association; Canadian Diabetes Association and Diabetes UK for example) now advise people with type 1 and type 2 diabetes to use the GI or GL as part of the nutritional management of their condition. 

For gestational diabetes: In their recently released guidelines, Initiative on gestational diabetes mellitus: A pragmatic guide for diagnosis, management, and care, the International Federation of Gynecology and Obstetrics have recently recommended a focus on lower GI foods. "Low GI diets are associated with less frequent insulin use and lower birth weight than in control diets, suggesting that it is the most appropriate dietary intervention to be prescribed to patients with GDM," they say.

For cholesterol: An analysis of 28 randomised controlled trials provided high-level evidence that high-fibre, low GI diets can significantly reduce total and LDL cholesterol levels, independent of weight loss. 

For weight maintenance: The Diogenes study from Europe found that a moderately high protein, low GI diet is the best for longer-term weight management.

Lower starch intake is one of the main trends that have been observed in diet and weight loss programs and it has been identified by nutritionists as a priority for 2018. However, survey after survey reports the difficulty people face in avoiding starch - which is much more challenging than avoiding sugar. Additionally, the market has many sugar-free products and sugar substitutes but no such aids are available for starch avoidance.