Hi worldfalls, welcome aboard.
Actually, what the manufacturer has done is .. they've pre-subtracted the fiber. So, those walnuts have 3 grams of digestible carb in them AND 3 grams of fiber in addition. (ie, 6g total).
This is the new way that labels on food products are headed, so low-carbers need to get used to the idea that soon, we will not need to subtract the fiber grams, it will already have been done for us. The actual carbs in the food that contribute calories and have an impact on blood sugar and insulin will be plainly shown on the label, and any fiber, which is not digested and therefore does not contribute calories or affect blood sugar, will be listed separately.
This trend is part of the FDA's and consumer groups' mandate to have labels that more accurately reflect the nutrient content of foods. The only problem is that not everybody is doing it yet, and it's very confusing. You need to be a detective to determine if the fiber has been pre-subtracted ... but generally, a net carb count of zero for a food that you think
should have carbs in it will be a clue
BTW, nuts and vegetables and fruits and salad greens even .. all contain a small amount of naturally occurring sugars -- ie, simple carbohydrate, not quite the same thing as white table sugar
. So it's those sugars that are showing on the label. It's the added processed and refined sugars, and high glycemic veggies and fruits that you should watch out for. The high fat content and fiber in nuts helps to offset the small amount of natural "sugar".
hope this helps
Doreen