Are you confused about net carbs? Not sure what they mean or how to calculate them? Then you are in the right place because I am sharing with you everything you need to know about net carbs from how to calculate them to what they mean for blood sugar management.
It’s important to start off by saying that “net carbs” is not an official term and there can be some confusion about how to go about calculating it… That’s exactly why I wanted to write this article for you! This blog will clear up any confusion you may have about calculating net carbs and why it matters.
Net carbs vs other carbs
Your body processes different types of carbs in different ways. Knowing the difference in how our bodies handle the various types of carbohydrates allows you to have better control over your blood sugar, which is especially important if you have diabetes.
So, what are net carbs?
Net carbs are essentially any carbs that are digestible. This includes both simple carbs and complex carbs. While simple carbs are simply one or two sugars linked together, complex carbs are comprised of many sugar units linked together.
Whenever you consume any carb-containing food, your small intestine breaks down the carbs into their individual sugar units so that they can be absorbed into your bloodstream.
However, some carbs (fiber and sugar alcohols) aren’t broken down into individual sugars, and thus they cannot be absorbed.
Since these types of carbs cannot be absorbed and are considered indigestible, we subtract them from the total carb count in order to calculate net carbs.
Fiber is a special type of carbohydrate that we don’t include in the net carb count because your body cannot digest or absorb it.
There are two categories of fiber: soluble and insoluble. Each of these types of fiber plays a different role in your body as it passes into the large intestine undigested.
“Insoluble” essentially means it is undissolvable, and this fiber type helps bulk up your stool and keeps you regular by preventing constipation. Insoluble fiber has no calories since it cannot be absorbed by the body. This also means that insoluble fiber has no impact on blood sugar or insulin levels.
Soluble fiber can dissolve in water, which helps to form a gel inside your digestive system that slows down the movement of food to keep you fuller for longer. Once soluble fibers reach the large intestine, your gut microbiome ferments them into short-chain fatty acids, which are essential for maintaining gut health.
Your friendly gut bugs help release about 1-2 calories per gram of soluble fiber. However, this doesn’t translate to blood sugar increases – in fact, it appears that this process can actually help to reduce blood sugar. Soluble fiber has been shown to help with blood sugar control as well as increasing insulin sensitivity.
One fiber that your body treats differently is called isomaltooligosaccharide (IMO). This is a processed fiber that can be partially absorbed by the body and raise blood sugar. Some low-carb foods may contain IMO, so if you are counting net carbs just be aware of this.
Another type of (mostly) indigestible carbohydrate is something called a sugar alcohol. There are many different types of sugar alcohols, and how your body treats each of them varies.
It is important to note that many sugar alcohols are partially absorbed by the body, some provide calories, and some can have a small impact on both blood sugar and insulin levels.
Maltitol is one example of a sugar alcohol that has an impact on blood sugar, with a glycemic index of 35. It gets partially absorbed in the small intestine, then your gut bacteria ferments the rest. Because of this, maltitol, which is found in many protein bars and sugar-free candies, provides around 3 calories per gram.
Luckily, the other sugar alcohols that may have an impact on blood sugar do so to a much lesser extent. Knowing which sugar alcohols have little to no impact on blood sugar is essential, especially when you have diabetes.
Erythritol is a great choice because while the vast majority of it gets absorbed into the bloodstream, it gets excreted in your urine without having any impact on your blood glucose levels. Additionally, it is considered essentially carb and calorie-free and doesn’t cause digestive issues for most people.
Calculating net carbs
Now that you know what net carbs are, and which carbs are excluded from the net carb count, you’re probably wondering how to go about calculating net carbs. The answer depends on what kind of carb-containing food you are consuming: whole foods or processed foods.
How to calculate net carbs in whole foods
Since whole foods contain natural fibers, calculating net carbs is simple. All you have to do is subtract the fiber grams from the total carbs, and there you have it: the net carbs!
The best place to look for this information is the USDA FoodData Database.
The formula for calculating net carbs in whole foods is:
- Net carbs = total carbs – fiber
How to calculate net carbs in processed foods
This is where it gets a little bit more complicated… Calculating the net carbs in processed foods is slightly less straightforward because you need more information.
First, look at the Nutrition Facts panel and see how many grams of fiber are listed underneath the carbs section.
In general, the fiber grams can be subtracted from the total carbs as long as you don’t see isomaltooligosaccharide (IMO) in the ingredients list. If you see IMO, then only subtract half of the grams of fiber from the total carbs.
Next, you want to look for the amount of sugar alcohols on the label.
You can subtract half of the grams of sugar alcohols from the total carbs, unless the sugar alcohol in the product is erythritol or allulose. In this case, you can subtract all of the sugar alcohols from the total carb count.
Many companies will calculate net carbs for you on their labels. However, you may get a different number when you do the calculations yourself. The companies tend to subtract all fiber and all sugar alcohol carbs from the total carbs in order to obtain the net carb count, although this is less accurate.
The formula for calculating net carbs in processed foods is:
- Net carbs = total carbs – fiber (or half of IMO) – half of the sugar alcohol (or all of the sugar alcohol when it is erythritol or allulose)
Counting net carbs: pros and cons
Now that you understand how to calculate net carbs, let’s talk about why you may (or may not) want to do that to keep track of net carbs in your diet.
One major advantage is that counting net carbs allows you to eat a greater variety of food when on a low-carb or keto diet. When you focus on total carbs, you may lose out on some really healthy foods that pack a hefty dose of fiber but have fewer net carbs.
Additionally, dietary fiber is extremely beneficial for your health, so limiting foods based on their total carb content can directly lead to lower fiber intakes, which can negatively impact health. Instead, counting net carbs allows you to get sufficient fiber in your diet.
A potential downside of counting net carbs is that it is not 100% accurate. Foods may have varying levels of soluble vs insoluble fibers along with different combinations of sugar alcohols. Most of the time, it is not possible to get a fully accurate net carb count.
It is also important to note that neither the FDA or the ADA recognize net carbs. In fact, the position of the ADA for people with diabetes is to focus on total carbs and not net carbs. The reason for this is that the equation used to calculate net carbs is not entirely accurate because the contribution of fiber and sugar alcohols to total carbohydrates depends on the types present. And since food labels do not always list the type of fiber or sugar alcohols used, it can be hard to accurately calculate net carbs. If you are taking insulin or on any medication to manage blood sugar levels, these inaccuracies can lead to negative consequences when it comes to blood sugar regulation. That is why many medical professionals and the ADA recommend instead that people with diabetes use
the total grams of carbohydrate and closely monitoring your blood sugar when consuming foods high in fiber or sugar alcohol to determine how they affect your body.
Remember, everyone is different and this should be a topic of conversation with your dietitian and diabetes care team to determine the best way to count carbohydrates for you and your individual blood sugar goals.
The bottom line: should you count net carbs?
Net carbs are essentially the carbohydrates that your body is able to digest and use as fuel.
When calculating net carbs, one subtracts the fiber and sugar alcohols from the total carb count, since these are not considered digestible carbs.
There are advantages and disadvantages to counting net carbs, but ultimately, the choice is up to you. If you are already counting carbs, you may now choose to count net carbs as it allows you to consume a greater variety of foods and higher amounts of fiber.
For some, counting net carbs may lead to higher blood sugar levels than expected. If this is the case, and especially if you have diabetes, you may decide that tracking total carbohydrates makes more sense for you. If you are taking any medication or insulin to manage diabetes, be sure to talk to your diabetes care team to determine the best way for you to count carbohydrates for your treatment goals.