Forgive my ignorance, what is GL?
GL is Glycaemic Load which is an updated version of GI (Glycaemic Index). Many of the popular diets are based on GL principles. It was originally a food plan devised for diabetes to keep blood sugar levels under control and even throughout the day. Keeping blood sugars level means that you don't have cravings or feel ravenously hungry.
Popular GL plans have been done by Rick Gallop/Nigel Denby/Patrick Holford. google any of them for more info. Any other queries, if I can help I will do my best.