What are "sugar alcohols?"

Sugar alcohols are low glycemic index so they do not spike insulin levels the way sugar and starch do. They do have calories and they are properly carbs, so many people call them hidden carbs. They are better than high glycemic index carbs. Although these substances are often subtracted from total carbohydrates and not included in net carbs on nutrition labels, to be exact about your carb intake, you should count half of each gram of sugar alcohol towards your daily carb allotment. (Sugar alcohols have, typically, half the calories of normal carbohydrates on a gram per gram basis.)

This Wikipedia link shows the calories in each sugar alcohol.