The way that the US outlines nutrition guidelines is you calculate the total calories, then you calculate how much fat and protein is in it. You subtract the fat and protein and what you're left with is "total carbohydrate". Carbs aren't actually calculated and are just assumed, which is why they're unreliable. For example, if you take Greek Yogurt, once the fat content and protein is determined, what you're left with is Total Carbohydrate. My Greek Yogurt from Trader Joe's has 7g of carbohydrate per cup according to the label, but this isn't actually correct. The fermentation process converts lactose into lactic acid, so the real carbohydrate content of my yogurt is actually around 3-4g per cup, so the label isn't factual. It's far more extreme for kefir, which is heavily fermented. That's just how the US mandates that carbohydrate is calculated.
In the case of the banana, if you have 25g of total carbohydrate and 12g of "sugars", the remaining would be dietary fiber, sugar alcohols and "other". Realistically, there's pretty much always a margin of error in Total Carbohydrate because it's the macronutrient that isn't calculated. It's just the sum total of fat, protein and whatever's left to get the total caloric value. But to answer your questions, no, it wouldn't have 37g of carbohydrate. It's just that roughly 50% of the carbohydrate found in a banana is sugar. The rest is starch, fiber, sugar alcohols and whatever's remaining from the margin of error in the calculations.
Last edited by ChocoTaco369; 10-09-2011 at 04:29 PM.
Don't put your trust in anyone on this forum, including me. You are the key to your own success.