Limitations of using glycaemic index (GI)

  1. Individual variations in GI response: Rate at which different individuals digest carbohydrates can vary, leading to individual differences in glycaemic response. This means that GI lists may not be reliable.
  2. Combining different carbohydrate foods with different individual GIs also alters the overall GI of that meal.
  3. A composite meal with protein and added fat for cooking also alters the GI of the meal itself.
  4. Not all low GI foods are healthy food choices. Fat lowers the GI of a food. Take chocolate for example. Chocolate has a lower GI because of its fat content, which slows the absorption of glucose into the blood stream but chocolate is very energy-dense and very calorific, also because of its fat content. This will not be to your favour, especially if you are trying to lose weight.

So, is it ok to focus on glycaemic index alone?

"Relying and focusing on GI alone is not a foolproof method to achieving optimal glycaemic control. Focusing on GI alone could lead to your diet being high in fat and calories, and being unbalanced," says Ms Kala Adaikan, Senior Principal Dietitian from the Department of Dietetics at Singapore General Hospital, a member of ​the SingHealth group.

This is because GI does not consider total macronutrient intake. It is the total amount of caloric intake that leads to weight gain and increased insulin resistance, and makes it harder to achieve optimal glycaemic control. In addition, it may increase your risk of heart disease.

Monitoring the total amount of carbohydrates you consume has a far greater and positive impact on overall blood glucose control than focusing on GI alone. Try not to exceed your carbohydrate requirements for the day.

See the previous page to learn the different factors affecting the glycaemic index of food.

Ref: O17