The book shelves and magazine racks seem to be full of titles hailing the virtues of using the glycemic index for weight loss.

But what is the glycemic index (GI) and just how can you put it to use in your weight loss and healthy living efforts?

Simply put, the glycemic index is a measure of carbohydrate quality...ie...the degree to which the carbohydrates in different foods will raise blood-glucose levels.

Essentially, the glycemic index is a comparison of carbohydrates based on their immediate effect on blood-sugar levels.

Carbohydrates that break down quickly during digestion have high glycemic index (GI) values. The blood-glucose response to these foods is fast and high ( a spike).

Carbohydrates that break down slowly, releasing sugar gradually in the blood stream, have a low glycemic index.

Use of the glycemic index to plan your diet is based on the following principles...

The blood-glucose (blood-sugar) response to a meal is primarily determined by its carbohydrate content. Both the quantity and quality of carbohydrate in the food influence the rise in blood glucose. Meals containing the same amount of carbohydrate can produce either high or low effects on blood glucose, depending on the type or quality of carbohydrate (GI value).

Carbohydrate is the starchy part of foods like rice, bread, potatoes and pasta and it includes sugars and certain types of fiber.

What happens in your body when you eat foods with a high glycemic index is that they are rapidly changed into sugar and your body responds by quickly producing enough insulin to transfer the sugars to your muscles. This is called a spike and you can actually feel a surge in energy. But this surge is short lived as when the insulin has taken care of the sugar, it drops to a low level very rapidly. This drop brings on hunger pangs which may trigger more of the same ups and downs.

So how can all of this knowledge help you with weight loss?

Perhaps the biggest challenge to losing weight (and staying on a diet) is constantly feeling hungry.

Foods with low GI values are among the most filling of all foods and delay hunger pangs for longer. These foods also generally have a lower energy density, meaning they contain fewer calories per gram than high GI foods.

The significance of this is obvious...eat lower GI foods (lower calories) and feel fuller longer.

There are many studies now that confirm that low glycemic index foods are able to suppress hunger for longer than high glycemic index foods.

Further, even when the calories (energy density) is the same for two foods, people eating the low GI foods will lose more weight than those eating the high GI foods.

Two more interesting facts about low-GI diets...

It is a common response of the body to drop the metabolic rate when a new diet is begun. Your body goes on the defensive and preserves fat stores thinking you are in a famine. Studies found that metabolic rates dropped less on a low GI diet than on a conventional, low calorie diet. There is evidence that low GI diets are able to reduce abdominal fat specifically. A new study suggests that pregnant women on a low-GI diet gain less body fat than those on an equivalent high-GI diet. A low GI-diet during pregnancy can minimize fat-gain and there is certainly no harm in it.

Tips for losing weight:

Instead of looking at which foods to eat less of, focus on eating the recommended fruits and veggies first and then see what space is left for the rest. Eat at least one GI food at each meal. Reduce your fat intake, especially saturated fat. Eat regularly...eating 4 to 5 times a day, including snacks, low GI foods maintains the feeling of fullness, keeps the metabolism stoked and prevents overeating at mealtimes.

So, whether or not you want to lose weight, or want to avoid type 2 diabetes and the many health problems associated with it brought on by insulin exhaustion, you can use your knowledge of the glycemic index to your benefit.