But it is short term only..
Although developed to help people with diabetes manage their food intake, the glycemic index has taken on new meaning as a weight loss strategy. In fact, several diet books tout the glycemic index as a foolproof way of identifying foods that raise blood sugar and insulin levels and therefore, can lead to weight gain.
But despite the hype, experts in nutrition and public health see very little practical use for the glycemic index and even the American Diabetes Association does not recommend this system for the prevention or treatment of diabetes. This is because of the many factors that affect the digestion of carbohydrates in the body. In fact, there is no clear evidence that avoiding foods high on the index is even beneficial.
see
http://www.essentialnutrition.org/glycemic.php