FDA has not permitted the use of whole-leaf Stevia or crude Stevia extracts because these substances have not been approved for use as a food additive. FDA does not consider their use in food to be GRAS in light of reports in the literature that raise concerns about the use of these substances. Among these concerns are control of blood sugar and effects on the reproductive, cardiovascular, and renal systems. Food additives and GRAS affirmation petition or pre-petition submissions for the use of such substances that FDA has received in the past have not contained the data and information necessary to establish the safe use of these substances as ingredients in food.
As far as sucralose, it substitutes three chlorine atoms for three hydroxyl groups on each molecule of sugar, again that is three substitutions per molecule of sugar. This increases the sweetness 600 fold and uncouples the taste of sweetness from the normal hormonal responses to sugar. Long term this can lead to excessive weight gain.