What is the difference between Total Carbohydrates, Glycaemic Carbohydrates, Available Carbohydrates, or Net Carbohydrates?
Total Carbohydrates consist of multiple nutrients, including dietary fibre, sugars, polyols, and starches.Some of these nutrients are not absorbed, digested, or metabolized in the body to yield Glucose. Glycaemic Carbohydrates (also referred to as "available" or "net" carbohydrates) are those nutrients that ARE absorbed, digested or metabolized in the body to yield Glucose.
In other words, a product like Xylitol, can have 99g of Total Carbohydrates per 100g, BUT, only 0.04g of those Total Carbohydrates are able to be absorbed, digested or metabolized, which would mean they would have 0 Glycaemic Carbohydrates.
Think of it like this: Imagine drinking a glass of water with some sand in it. The glass with the water and sand represents the Total Carbohydrate. The water represents the Glycaemic Carbohydrate – these can be absorbed / digested / metabolized in the body; however, the sand will basically go in and then go out of your body as extra fibre – no absorption, no digestion, and no being metabolized into Glucose.
In SA the Department of Health changed the Labelling Legislation in 2012 to reflect Glycaemic Carbohydrates instead of Total Carbohydrates for this very reason.
To get a better indication of the Glycaemic Carbs instead of the Total Carbs of a product (if the label still lists Total Carbs) you would need to subtract the Fibre, Polyols, Sugar Alcohols, and Starches.