As the name suggests it definitely claims to have less calories than the normal pepsi drink. But its totally upto the person himself whether he can really diet by drinking it. I wonder how? If hes grabbing a cheese pizza or burger along with this diet drink...oops, how the hell is it going to help him.
However if you are the extremely calorie conscious kind and are addicted to other soft drinks, this might help you if you know how to maintain the proper balance by seeing what you eat along with it. The taste is bad but here in the US I see almost every second person with this drink which really shocks me. So I guess one can get used to the taste. Think before you get hooked on to these diet labels. Its all in the mind!