The glycemic index (GI) is a ranking system for carbohydrates' effect on blood glucose levels. It compares available carbohydrates gram for gram in individual foods, providing a numerical, evidence-based index of postprandial glycemia. The glycemic load (GL) is a ranking system for carbohydrate content in food portions based on their GI and the portion size. These two markers increasingly are being used to prevent typical diseases of the Western world, including type 2 diabetes mellitus, cardiovascular disease, obesity, metabolic syndrome, and acne. Data on the efficacy of GI and GL in the treatment of Western population diseases are discussed and critically evaluated, with a particular focus on acne and other skin disorders.