Only carbs that have the normal 4 calorie per carb count, starch, sugar, fiber, and glycerine are required to be on the nutritional label. Fiber is of course subtracted from the calorie count as it isn't absorbed. (Of course some fibers are absorbed which is another issue.) Sugar alcohols (polyols) however are not required to be listed on the nutrition facts as yet. The ingredient is required on the ingredients list. Because they are approximately 2 calories per gram instead of 4, it upsets the calorie count. Therefore manufacturers have the option whether or not to list sugar alcohols until this is resolved. Because sugar alcohols are 1/2 the calories of carbohydrates they count as 1/2 a gram of carb for every gram of sugar alcohol for diabetics.
Sugar alcohols: hydrogenated starch hydrolysates, sorbitol, xylitol, maltitol, isomalt, lactitol, mannitol, and erythritol. These are not absorbed in the small intestine like most food. They are absorbed partially in the large intestine causing fermentation and gas.
Technically, since the sugar alcohols are absorbed by insulin-independent mechanisms, they shouldn't disturb ketosis (on paper). In other words, since they don't create a significant rise in blood glucose and insulin levels, then supposedly your body can't use any small amount of glucose they may make or store it as glycogen. However, because they have calories, they are used as fuel by the body bypassing the Maillard reaction used by ketone bodies.
Everyone has an individual metabolism and must see how they react to each product. For some people, the so-called "hidden carbs" of sugar alcohols and glycerin do not take them out of ketosis. For others they must stay away. If you are losing while eating these bars, then no worries.
http://www.caloriecontrol.org/redcalqa.html