Coke Zero is sweetened with a blend of aspartame and acesulfame potassium (Ace-K) . Aspartame is an artificial sweetener used in place of sugar in many foods and drinks to provide people with a reduced, low or no sugar and calorie option. Coke Zero contains zero calories and sugar while providing the signature Coca-Cola flavor, making it an appealing drink among those trying to reduce their sugar intake or control their weight.