When using a low carb bar, there are impact carbs and total carbs on the label. The total carbs are MUCH higher than the impact carbs. When counting your daily carbs, should I use total or impact?

Count impact carbs. Impact carbs are similar to the ECC (effective carb count). Usually, you take total carbs, subtract the carbs for fiber and sugar alcohols (if they are listed), then you get a net carb number.

Yruam, this is one of those YMMV issues - your milage may vary. The 'impact' carbs they discuss on "LC" bars are usually sugar alcohols and glycerine - not fiber, as with whole foods. Sugar alcohols and glycerine can actually cause problems for many - some diabetics experience an insulin spike from them. Your best bet is to try them and see for yourself. If you start to stall out, or you losses slow and /or you start to experience cravings then you know that they're a problem for you. If not, then more power to you.

HTH
Nat