Learning about — and dealing with — carbohydrates is pretty much a given if you have diabetes. Most people quickly learn that foods containing carbohydrate impact their blood sugars. And many people “count” their carbs to help keep blood sugars within a target range. Some people who don’t have diabetes focus on carbs, too, especially if they are following a low-carb or keto eating plan. Making sense of carbohydrates is often challenging because there is more than one type of carb — starches, sugar, and fiber, to be more exact.
There’s another “type” of carbohydrate that pops up frequently on social media and on some food products called “net carbs.” What are net carbs? Are they another type of carbohydrate that you need to be watching out for?
To get cutting-edge diabetes news, strategies for blood glucose management, nutrition tips, healthy recipes, and more delivered straight to your inbox, sign up for our free newsletters!
A quick carb primer
If you’re a little murky about carbohydrates, here’s a quick refresher. Carbohydrates (carbs) are sugar molecules. Carbs, along with protein and fat, are one of three main nutrients founds in foods and beverages.
When you eat or drink carbohydrate, the body breaks that carb down into glucose, which is a type of sugar that the body uses for energy. Your body’s cells, tissues, and organs use glucose to function and do their respective jobs. Glucose can be a quick source of energy to be used immediately, and it can also be stored as glycogen in the liver or muscle for later use.
There are three main types of carbohydrate:
These are sometimes called simple carbohydrates because they are in the most basic form. Sugars are added to foods, like candy, desserts, and regular soda, and they are also found naturally in some foods, such as fruits, vegetables, and milk.
These are sometimes called complex carbohydrates, which means that they consist of chains of simple sugars strung together. The body has to break down starches into sugar in order to be used for energy. Starches include bread, pasta, and cereal, as well as some vegetables, such as corn, peas, and potatoes.
Fiber, too, is a complex carbohydrate. But unlike starches, most fibers aren’t broken down. Foods high in fiber help to fill you up, and they also help promote bowel regularity so that you don’t get constipated. Some fibers help lower blood sugars and cholesterol, too. Fiber is found only in plant foods, including vegetables, fruit, whole grains, beans, nuts, and seeds.
How do net carbs fit into the carbohydrate picture? You should know that the U.S. Food and Drug Administration (FDA) does not formally “recognize” the term “net carbs.” (The FDA regulates most food labels in the U.S.).
But, if you DO see the term “net carbs,” it refers to the carbohydrates in food that you can digest and use for energy. The calculation of net carbs is the total amount of carbohydrate in a food, minus the fiber and any sugar alcohols in that food. (Sugar alcohols are another type of carbohydrate that are chemically similar to sugar, but they aren’t completely digested or absorbed. Sorbitol, mannitol, and erythritol are examples of sugar alcohols).
So, once again, here is the net carb calculation:
Net carbs = total carbohydrate grams minus fiber grams and minus sugar alcohol grams
Here’s an example of how this calculation actually works, using a real food example of one-half cup of cooked black beans:
20 grams total carbs – 8 grams fiber = 12 grams net carbs (there are no sugar alcohols in beans, by the way)
And here’s an example of a “keto” food, Keto and Co’s Shortbread Keto Cookie Mix. One cookie (prepared):
9 grams total carbs – 5 grams fiber – 2 grams erythritol = 2 grams net carbs
When you do the math and see that a food, such as this cookie, has only 2 grams of (net) carbs, it’s easy to get excited! Two grams of carbohydrate is technically a “free” food. So that means you can eat a lot of these cookies (or similar keto or low-carb foods) and not have them impact your blood sugar or your waistline, right? Not necessarily.
Taking net carbs with a grain of salt
There’s nothing inherently wrong with calculating net carbs. It’s what you do with the information that’s important. Here are some tips to help you make sense of net carbs — and carbs, in general.
- Despite the hype generated by the low-carb and keto communities, there isn’t enough research to support only counting net carbs. Counting total carb grams is more evidence-based, plus a lot easier than doing a calculation.
- If you have type 2 diabetes, know that the American Diabetes Association no longer recommends subtracting the grams of fiber from total carbohydrate grams, as there is no evidence that doing so improves blood sugars. However, if you find that you have low blood sugars after eating higher-fiber foods or meals, talk with your dietitian about subtracting half or all of the fiber grams.
- One benefit of calculating net carbs is that it can help you focus on getting more higher-fiber foods in your eating plan.
- Subtracting all of the sugar alcohols from total carbs isn’t necessarily accurate — that’s because some sugar alcohols CAN raise blood sugar levels, especially if you consume too much of them (not to mention that sugar alcohols can cause bloating, stomach upset, and diarrhea in some people). As with fiber grams, it is likely unnecessary to subtract sugar alcohol grams if you have type 2 diabetes.
- Calories still count. If you decide to count net carbs, keep in mind the calorie content of the foods that you’re eating. Remember those keto shortbread cookies with just 2 grams of net carbs? Each cookie has 140 calories, thanks, mostly, to the 14 grams of fat in each cookie.
- Go ahead and try lower-carb or keto foods if they are appealing to you. But experiment a bit to see how these foods impact your blood sugars. You can do this by doing paired checking (checking your blood sugar with your meter before eating and about two hours later) or by checking your CGM before and two hours after eating.