Basically when on this diet or woe you count only the carbs listed as impact or net effective carbs (there are lots of names depending on which company's products you use). The 2g that you saw were the impact carbs. These are the only carbs that will affect how your blood sugar rises. I don't know about other low carb diets, but when doing Atkins you don't need to add sugar alcohol carbs or fiber carbs to your daily count.

Here are some links that may help:
Fiber: A Special Kind of Carbohydrate
How to Read a Food Label

Hope this helps!