You probably fall into one of two categories:

1) You've never heard of the term "glycemic index." 2) You've heard of the term "glycemic index" (it comes up a lot in our chats) and you want to know what it is, thinking it may help you in your weight loss program.

Whenever you see the prefixes gly- or glu-, chances are someone's talking about sugar.

• Glycogen: the form of sugar stored in your muscles and your liver
• Glucose: the form of sugar floating in your blood
• Glycolysis: the process of breaking down sugar for energy
• Glucose tolerance test: a test performed by a doctor to look at your response to sugar

So if you deduced that the glycemic index has something to do with sugar, you're right. The glycemic index is a relative measure of how fast a given food raises blood sugar. Why that's important will be the subject of many future columns, and might just be the hottest topic in popular nutrition books (with good reason). The short version is this: When blood sugar goes up, the pancreas responds with a shot of insulin. Insulin is a storage hormone: One of its jobs is to escort the sugar from the blood into either muscle or fat cells. What we're now finding is that, important as insulin is, several things do and don't happen when insulin levels are high.

For one thing, the body doesn't burn fat. The faster a food raises your blood sugar, the higher the insulin response.