Caloric reduction is the main advantage of artificial sweeteners. But it is not calories that drives obesity; it’s insulin. Since artificial sweeteners also raise insulin levels, there is no benefit to using them. Eating chemicals that are not foods (such as aspartame, sucralose or acesulfame potassium) is not a good idea. They are synthesized in large chemical vats and added to foods because they happen to be sweet and not kill you.
