The GI diet explained how to manage blood sugars levels to help weight loss and encourage long-term good health. The GL (glycaemic load) is an exciting new extension of these principles and measures more accurately the carbohydrate load of food. This means that foods that had previously been considered high GI, e.g. melon, can now be introduced into your diet, as the amount of carbs you would eat in a portion, rather than in a whole melon, is calculated.