When looking at a label on food, it's pretty much possible to calculate the calories based on the carbs, fat, and protein listed even if the calories weren't listed. Right?
But with carbs, there is sugar and fibre listed underneath it, but it doesn't add up to the total carb count. So (looking at a random label here), if something says it has 32g of carbs per serving, 5g of fibre, and 1g of sugar, what makes up the additional 26g of carbs? Is that empty space made up of "complex" carbs? Is there a way to approximate the glycemic index of a food (or at least the percentage of a food that is sugar) based on the ratio of sugar versus carbs listed?