I'm not sure why that other poster would say only water has zero calories. If the whole can of pop might have greater than zero but less than one calorie then you don't really need to count that calorie in your diet. I am here to tell you, "Zero" has effectively ZERO calories.
NOW, the question you have to ask yourself is this: is avoiding caloric intake worth consuming sweeteners that might have adverse health effects in ways other than weight/calorie intake?
Note that I said 'MIGHT.' I will drink the occassional diet pop as well as the occassional regular pop, but I am leery of the idea of drinking a couple of 'non sugared' sweet drinks each day. I wonder how healthy that is. tulsa