What are 'Net Impact' Carbs?      The term "net impact carbs" refers to the total carbohydrates in a product minus fiber, sugar alcohols and other carbs that don't increase blood sugar levels. Products that are low in net impact carbs won't raise blood sugar much and therefore won't increase insulin secretion. Fat storage is encouraged by insulin, so keeping it low for most of the day helps to prevent fat gain. Protein bars with low net impact carbs contain sugar alcohols called polyols - organic sweeteners that are 40-90% as sweet as regular sugar. Unlike regular sugar, the polyols are not easily absorbed by your body. In other words, they mostly go right through you. Technically, sugar alcohols don't contribute many calories to a diet. But this can vary depending on the sugar alcohol. Although carbohydrates typically contribute about four calories per gram, sugar alcohols may contribute from one and a half to three calories per gram, depending on which sugar alcohol you're consuming. The most common sugar alcohols listed on nutrition labels are xylitol, sorbitol, mannitol, maltitol and polyglycitol (hydrogenated starch hydrolysate, or HSH).  The bottom line is, you only need count the 'net impact' carbs.