Question on "No Calorie" candies

I just bought a pack of Ice Breakers Sours, which claim to have no sugar, fat or calories.

I love these things because they really help with my sweet tooth, but my question is, how can these things have NO calories.

Does any one know of any negative effects of say, eating the whole container?

If you by them in a package of 2 (which comes in another layer of packaging) it actually says that they contain 3 calories per candy. On the actual hard package however it says zero calories. Its a little wierd that they do that.

I love Icebreaker sours! I've had both kinds (green or purple packaging) and they're so good!

My rule for things that claim to be "calorie free" is this - I just add 5 calories per serving. This goes for sweetener packets, spices, etc..