Cecil’s take on calorie calculation matches up with the common wisdom, but according to this slightly more recent article written by a food scientist, calorie calculation is a bit more sophisticated than that. Have a read and see what you think.
Interesting … here in the good ol’ U.S. of A., many food product labels show not only the total carbohydrate content of a serving, but also break this down into “dietary fiber”, “sugars”, “sugar alcohols” (if any), and “other carbohydrates” (e.g. starches).
As pointed out in that article, the dietary fiber portion of the carbohydrate content is essentially indigestible and should be subtracted from the number of “Calories” delivered by a serving. However, this subtraction is not done on the food product label itself, thereby making high-fiber products look like they’ll contribute more Calories toward energy/weight-gain than they actually will.
Prehaps the FDA should allow food manufacturers to put a “fiber calories” entry alongside the “fat calories” entry on the standard Nutrition Facts label, thereby making it easier for the consumer to subtract those calories out.