What purpose does it serve?

We now know that carbohydrates are a major factor in weight gain. Carbohydrates arewith a high glycaemic index are quickly released into the bloodstream and tend to be stored as fat. By causing a peak and then a drastic fall in blood sugar levels, they also favour energy slumps and hunger pangs.

This is where GI can work for you: if you're looking to lose weight, take a look at your diet and go for low over GI high foods. It's also an important concept in the treatment of diabetes, and it's also important for people who do sport.