When you hear the term ‘glycaemic index,’ you probably fall into one of two categories:

1. You've never heard of it or you've heard of the term and you want to know what it is, thinking it may help you in your weight loss programme.
2. Whenever you see the prefixes gly- or glu-, you think someone's talking about sugar.

Well, here’s a mini-glossary:

• 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 glycaemic index has something to do with sugar, you're right. The glycaemic index is a relative measure of how fast a given food raises blood sugar. The reason this is important is: 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 elevated.

For one thing, the body doesn't burn fat. The faster a food raises your blood sugar, the higher the insulin response. So, knowing just how fast a food you eat ‘breaks down’ into sugar — and thus how quickly it raises blood sugar levels, producing a high insulin response — is crucial in weight loss. It's also one of the key areas where ‘us’ and ‘them’ don't agree. ‘They’ — meaning traditional medicine practitioners and dieticians — tend to believe the connection is unimportant.

Anyway, the glycaemic index was developed to determine how fast a food brings your blood sugar up, which, incidentally, also contributes to mood and energy fluctuations. The people who developed it used pure glucose as a standard, giving it a rating of 100. The closer to 100 a particular food is, the higher its glycaemic index.

Here are a few representative samples (some numbers vary because there are different versions of the scale):

Nuts: 15-30
Cherries: 25
Beans: 30-40
Bananas: 60
Rice cakes: 80-133
French bread: 95+
Many processed breakfast cereals: 100

One food was a real standout, however. It's a complex carbohydrate, too, and blew the theory that these kinds of carbohydrates are always slower-releasing and 'better' for you. Want to guess what it is?

The bagel, which weighed in at 105. It beat the gold standard of pure glucose.

Now, the take-home point from this is not that high-glyacemic foods are ‘bad’ and low-glycaemic foods are ‘good’. In fact, high-glycaemic foods are useful if you're training twice a day and need the fastest replenishment of muscle glycogen stores.

But if you're trying to manage your weight, go with the lower-glycaemic foods as snacks. Eat the higher ones, if you must, with a little fat or protein to slow the response. Or avoid them completely for the time being, and begin to be aware of the powerful effect high insulin levels are having on your attempts to lose weight.