How do low-calorie sweeteners affect your weight? It depends. Researchers randomly assigned 123 people with overweight or obesity to drink roughly 40 to 60 oz. a day of Kool-Aid sweetened with sugar, aspartame (Equal), saccharin (Sweet‘N Low), stevia extract (Truvia), or sucralose (Splenda). The sugar-sweetened drink supplied 400 to 560 calories. (Heavier participants got larger servings.)