How to calculate net carbs
In this article, I’m going to share with you the very simple formula that you need to work out Net Carbs. I’ll also show you a couple of examples of how to calculate net carbs for individual foods, for recipes and from ingredient labels.
Please read to the end because there is one food group that makes things a bit more complicated that you need to be aware of.
Table of Contents
There has been a debate in the low carb community for many years about whether or not we should count Total Carbohydrates or Net Carbohydrates.
I’m not going to get into that debate here, that’s for another article. I’m going to focus instead on how to calculate net carbs in your food.
UK/EU vs USA food labelling
In the UK and the EU the food labelling of carbohydrates is already shown as net carbs so there is no need to calculate anything, with the exception of the issue discussed towards the end of this blog.
In the USA however, food labelling shows total carbohydrate, so you do need to work out your net carbs.
The formula is very simple:-
Total Carbohydrates – Fibre = Net Carbohydrates
But it’s important that we understand what this means, so I’m going to break it down for you.
What does this mean?
Total carbs are all the different types of carbohydrates that you find in any given food.
It’s anything that can be broken down into smaller sugar molecules and could include;
Refined carbohydrates – such as sugar.
Starches – still linked chains of glucose molecules that are broken down within the body into glucose molecules.
Fiber – also a form of carbohydrate – because it’s glucose molecules linked all together – but the way they are linked together means that the human body can’t use it.
Fiber is basically the cellulose walls of plants and some animals can digest fibre and they are called ruminants!
So by subtracting the fibre from the total carbohydrate, we’re trying to find out how much of the carbohydrate is actually used by our bodies.
Practical examples of How to Calculate Net Carbs
The nutritional information comes up over here on the right side).
Now, the amounts given are in grams per 100 grams which is pretty much universally how this stuff is shown.
For every 100 grams of broccoli there are 7 grams of total carbohydrate of which 3 grams are fibre
So if we put that into the formula, we get 7 – 3 which equals 4 grams of net carbohydrates… the bit that the body can use.
Let’s look at a different example which will hopefully show you the importance of net carbs.
So for every 100 grams we can see that there are 42 grams of carbohydrate in total… but 34 grams are fibre which the body can’t use.
So 42 – 34 equals 8 grams of net carbs per 100 grams.
If we’d just counted the total carbs then you’d probably be trying to avoid chia as a food source, but because most of that carbohydrate is in the form of fibre you’re pretty much good to go.
In fact, I’ve got several chia seed based recipes on my website at carbdodging.com
Meals not just ingredients
We don’t just eat ingredients on their own. We eat these foods as part of meals or recipes…
Many recipe websites will display the total carbs and fibre content of food, and some may also calculate the next carbs for you.
But if you’re creating your own recipes there are a number of different tools that make it easy to find the figures you need.
I use the fitness software myfitnesspal – which will help you calculate the total carbs and fibre in a recipe, which you can just put into the formula.
So here at Carb Dodging we promote a Low Carb Diet, from real, unprocessed foods. And real foods don’t tend to have ingredient lists or nutrition labels. But if you’re out and about, or haven’t had the chance to prepare your own food one day then you’re going to want to know how to work out the net carbs of a food from the nutritional label.
Be aware that the label will usually show the nutritional information per serving, and not always per 100 grams. Sometimes they do show both.
The information you need to look for is highlighted in the image below.
On this label the total carbohydrates are 4 grams with 1 gram of fibre. So 4 minus 1 is 3- so this has net carbs of 3 grams per serving.
Pretty simple huh?
So where does this get complicated? It gets complicated when we come to processed foods with artificial sugars in them in particular – sugar alcohols.
Sugar alcohols are things like xylitol, erythritol, sorbitol, malitol – basically if it ends in -tol its a sugar alcohol.
Now this is a grey area, but technically, these are also considered as carbohydrates.
Take this bar for example. This is marketed as a low carb bar here in the UK. It makes its claims of being low carb based on the fact that it has 2 grams of sugar per bar.
But it contains 13 grams of sugar alcohols for a total carbohydrate count of 22 grams.
Now unlike fibre, sugar alcohols have variable absorption from the gut, and they can affect your blood sugar, and insulin production and so probably should be counted as part of the net carbs.
So whether products are labelled low carb or keto. then the only way to be sure that you’re not going to mess up your carb counting is to count the sugar alcohols as part of your carb count. In fact, I’d just take the total carb count.
For real, unprocessed foods – the net carb calculation of total carbohydrates – fibre is what you should use.
But for processed foods, even when they may be labeled low carb… it’s probably better to use the total carb figure instead.
Hopefully you have found this guide helpful for tracking your carb intake.
Check out my other posts and videos for loads more information on a low carb/ keto way of eating.