A glycemic index (GI) is a theoretical value representing the characteristics of a single raw material. However, foods are a mix of many raw materials that will have an impact on the final result. GI of foods that are nowadays readily available on the Internet and that serves as an indicator for the suitability of food for those who suffer from diabetes, or those on a healthy or weight-loss diet, has been developed based on observations in human subjects and there is no evidence whether or not it is easily transferrable to animals. On the contrary, there have been very few instances when GI of the raw material was determined directly in an animal subject.
In theory, we may infer that the difference in GI will be noticeable between the groups of foods classified as
1. Economy food – with high content of carbohydrates and low protein and fat content
2. Premium and super-premium foods – with medium carbohydrate, protein and fat content
3. The so-called "Low carbohydrate diet" – with low carbohydrate content and high protein and fat content
The classification of foods according to GI is mostly important for patients suffering from obesity and diabetes. For normal healthy dogs and cats, the importance of GI is not evidenced in the literature and most of the data used are obtained from observations in human subjects and for now it seems as an invalid argument and instrument only to differentiate the food.
Ing. Jan Jirásek