Most people with diabetes must rely on counting carbohydrates when they eat food to help manage their blood sugar levels.
But that can become trickier when food labels sometimes differentiate between “total carbohydrates” and “net carbohydrates”.
What is the difference between these two types of carbohydrates and which one should you use for your diabetes management?
This article will explain what total carbohydrates are, what net carbohydrates are, and how to determine when to use each number.
Why is carbohydrate counting important?
At the molecular level, carbohydrates are broken down into glucose in the bloodstream that only insulin can break down and help the body’s cells to digest.
If you live with insulin-dependent diabetes, counting carbohydrates will therefore help inform your insulin dosage decisions.
If you live with non-insulin-dependent diabetes, you may count carbohydrates to better calibrate oral diabetes medication like Metformin, or even exercise, to help manage blood sugar levels.
Since people with diabetes either struggle to make enough insulin naturally or their bodies make no insulin at all, making sure one is aware of the number of carbohydrates in a food that’s consumed is vital to good health and wellbeing.
What are total carbohydrates?
According to the Food and Drug Administration (FDA), total carbohydrates tell you the absolute total number of carbohydrates a serving size of a given food has.
If you live with diabetes, this also nominally tells you how your blood sugar will be affected by a certain food. The “total” means that the number is comprised of four things:
- Total sugar – This is the total grams of naturally occurring sugars that are found in the serving size of a given food
- Added sugar – This is the total grams of artificially added sugar that were added during the processing of a certain food (like dextrose or sucrose). Also commonly found here would be grams of sugar from table sugar, honey, or agave nectar
- Dietary fiber – Total grams of fiber which cannot be broken down easily by the GI tract of a human being
- Sugar alcohols – Total grams of sugar alcohols. These are a type of sugar (polyol) with a slightly different chemical makeup than added sugar, resembling both sugar and alcohol. They have minimal effects on blood sugars and are commonly added to food to give them a sweeter taste, without the added carbohydrates and calories. Examples of sugar alcohol include: xylitol, sorbitol, maltitol, and erythritol
Together, these four numbers comprise the total number of carbohydrates in a given serving size of a food.
While this is an extremely helpful way to figure out how a food will affect your blood sugar, it doesn’t tell the whole story.
What are net carbohydrates?
Net carbohydrates represent the total number of carbohydrates that will actually affect blood sugar levels. Sometimes they are called “digestible” or even “impact” carbs.
While there is no official definition of the term “net carbohydrate”, for people who are either eating a low carbohydrate diet or for whom counting carbohydrates is extremely important (i.e. people with diabetes), it is important to know how to calculate this.
Since naturally occurring fiber isn’t broken down in the small intestine, the carbohydrates that accompany this macronutrient do not affect blood sugar levels.
Additionally, subtracting sugar alcohols from a food (typically they only exist in processed foods) helps give you the net carbohydrates as well, since they are also not digested in the same way a typical serving of sugar is.
Studies show that sugar alcohols don’t seem to have a major impact on blood sugar levels, but people’s individual responses can vary. This is why sugar alcohols are commonly added to “sugar-free” candies, ice cream, and bubble gum, although they can cause bloating and GI discomfort.
Sugar alcohols seem to only be absorbed into the bloodstream briefly, and then exit the body through urine, making their impact on blood sugars minimal.
How do you calculate net carbohydrates?
To calculate net carbohydrates, one would take the total number of carbohydrates and subtract both the total number of grams of fiber and the number of grams of sugar alcohol.
However, since sugar alcohols can affect blood sugar minimally, and everyone digests sugar alcohol differently, some people may prefer to subtract only half the number of sugar alcohols for net carbohydrates.
Net Carb = Total Carbs – Fiber – Sugar Alcohols (or 50% of sugar alcohols)
The resulting number is the net number of carbohydrates in a serving of food, and for optimal blood sugar management, one would count that as the number to base insulin and/or oral diabetes medication on.
Mindy Nichols, RD, CDE says, “Net carbs are only estimations, as everyone’s digestive systems and bodily processes are different. Working with your doctor, experiment and see what works best for you!”
It’s important to note that if you live in some countries outside of the United States, the “total carbohydrate” number already has the total grams of fiber subtracted out, so there is no need to do the equation.
Pros and cons of counting net carbohydrates
Counting net carbohydrates is an excellent way to fine-tune your diabetes management, but it might not be for everyone. Here are some pros and cons of approaching this way of eating:
- Eating this way promotes whole, unprocessed foods
- It incentivizes eating more fiber
- Decreases risk for hypoglycemia
- It’s a less restrictive way of eating (can promote eating more fruit and other higher carbohydrate whole foods due to their high fiber content)
- May not be suitable for everyone’s eating plan or diabetes medication regimen
- Can result in eating lots of “sugar-free” candies and treats that aren’t as healthy (if the focus is only increasing the number of sugar alcohols and not fiber)
- Isn’t always 100% accurate for dosing
- Food labels aren’t always available (for instance at family or friend’s homes, and when out at a restaurant)
Lauren Plunkett, RDN, CDCES, author of Type One Determination, encourages people with diabetes to increase their intake of fiber-rich foods to enhance insulin sensitivity, lower inflammation, and promote the microbiome for a healthy body and mind.
“Everyone digests and absorbs food differently. This can depend on age, the environment inside the gut, and activity level. No two stomachs are alike! Since we are unique digesters, it’s important to determine which food sources of fiber are most compatible with our system and blood sugar goals, whether or not we choose to subtract fiber grams from total carbohydrates.”
Knowing both the total number of carbohydrates and the net number of carbohydrates in a food you’re eating is important, especially if you live with diabetes.
Calculating the net carbohydrates of a food can fine-tune both your medication dosages as well as your diabetes management, resulting in better blood sugar levels, lower hba1c levels, and an improvement in quality of life.
However, eating for diabetes is not a one-size-fits-all endeavor, and everyone’s experiences may vary.
Always talk with your doctor before making any changes to your eating and/or medication management plan.