By Greg Smithers The glycemic index, more commonly known as GI, ranks carbohydrate foods according to their effect on glucose levels in the blood. High GI foods are absorbed rapidly and lead to a quick rise in blood glucose levels. Low GI foods, in contrast break down more gradually and produce more stable glucose levels in the blood. This, in turn, leads to less fluctation in mood and energy. As low GI foods take longer to digest they release energy into the bloodstream more slowly. This ste