No its not just for G.I - Joe
So lets just go through what exactly Gi is/means........lets keep it simple.
G = Glycemic
I = Index
Glycemic Index refers to the rate at which CHO aka Carbohydrates break down in your digestive system to form glucose aka sugar. So there are different classes of of Gi as follows
HIGH Gi - these foods are quickly digested - Fast energy
MEDIUM Gi - the mid ground - Medium energy
LOW Gi - These are foods that digest slowly - slow steady energy
High Gi foods are quickly digested into your system creating a spike in your blood sugar levels creating the all too noticable sugar rush. Therefore if you go to the low Gi foods they are slowly broken down into your system delivering a steady stream of glucose.
If you eat a low Gi meal you will feel fuller for longer and your blood sugar levels will be at a more stable rate.
Not to say we should write off the high Gi side as these can be useful especially when you are exercising. After exercise your body is depleated of its energy and needs to be filled quickly so the body dosent take the energy from other sources. So a high Gi drink/snack is good to top levels back up and keep your fitness improving.
There are a number of books giving the Gi of foods so if your interested get a book and give it a go :)