Question: how many calories in 1 can of diet coke?
Answer: A 12-ounce can of Diet Coke contains 125 mg of aspartame, 113 mg of which is the "protein" aspartylphenylalanine (5). So, that can contains 0.452 calories. This is a very small number, but it is not zero. By comparison, a 12 ounce can of Coke contains 150 calories - 335-times that found in a Diet Coke.