I think those kind of things are usually traps. I've found they've gone to great lengths to reduce calories as those tend to be the key factor for the figure and health conscious people. But while stripping off calory-rich nutrients such as fats and proteins, the sugar content has remained the same or has even increased to make up for the loss of fats.

100 calories..fair enough..but it's not really healthy for you if it's like 20% of your daily recommended sugar intake in one very quick and small go.