OK, my take on this is that I need a framework to operate within. The frameworks I have chosen are Weight Watchers because it gives me a daily food budget which

OK, my take on this is that I need a framework to operate within. The frameworks I have chosen are Weight Watchers because it gives me a daily food budget which I can fine tune depending on whether I think I am losing enough weight (0.5-1Kg/week). The specific food choices are informed by Glycaemic Index principles which ranks foods based on the body's glucose response and hence provides a measure of how effective the food item is at keeping you feeling fed. I get the impression that GI is not highly regarded in the USA, if so why is this?