Article – Glycemic Index
Glycemic Index (GI) has become the basis for many diets, and even those that don’t mention it explicity will talk in terms of “good carbs” and “bad carbs”. Glycemic index is a measure of how quickly the carbohydrates in food get converted to blood sugar. The lower the number, the slower the food gets converted. Slower conversion leads to more steady blood sugar levels, which promotes better weight loss and better overall health. Spikes in blood sugar levels trigger increased insulin output which causes the body to store fat, while steadier blood sugar will result in more overall energy and less hunger.
For better health and better weight loss, foods with lower glycemic indexes are preferrable and many diet plans emphasize these. Examples of low glycemic foods include legumes/beans, oats, oatmeal, barley, bran, and most fruits and vegetables (but not potatoes). These are the “good carbs”. Bad carbs are those that converted to sugar very quickly like potatoes, white bread, and white rice. Generally speaking, the good carbs include fiber. Fiber helps to slow down the conversion to blood sugar.
Not only fiber, but protein and fat also help slow down the conversion to blood sugar. So while some foods have a low glycemic index, it is also possible to make any meal better in terms of blood sugar by including fiber, protein, and even a little fat. This is why many diet plans emphasize high protein and high fiber, and this is why you can sometimes include some of the bad carbs in your diet as long as you control the portion size and balance the meal out with plenty of protein and fiber.
For more information, check out Glycemic Index Online or Wikipedia.