What Are Net Carbs & How Do You Calculate Them?
Written by Chrissy Arsenault, MBA, RDN, LD
Not all carbs are created equal.
Carbohydrates (‘carbs’) often get a bad rap altogether, but they shouldn’t – your choices of carbs matter when it comes to your health.
Complex carbs are found in foods like legumes, vegetables, and whole grains. These carbs have multiple sugar molecules linked together, so your body takes longer to break them down. Complex carbs are also important sources of dietary fiber.
Simple, refined carbs can be found in foods like sugary drinks, baked goods, and breakfast cereal (hint: mostly foods with added sugar). These carbs only have one or two sugar molecules linked together, so they are absorbed rapidly in your body and can result in a spike in your blood sugar, unless paired with adequate intake of protein. Pairing carbs with protein can slow the digestion of carbs and help you feel fuller after eating.
Other ingredients in food that act like carbs but are not actually carbs include low calorie sweeteners sugar alcohols, and glycerin. They taste like sugar but contain few or no calories. Dietary fiber is also counted in total carbs, but act differently than your typical ‘carbs’. These ingredients are not metabolized by the body like carbs – which leads me into my discussion of net carbs and why they matter.
What Are Net Carbs?
Net carbs, also called ‘impact carbs’, refer to the amount of carbohydrates that are absorbed and used in the body. Net carbs can come from either simple or complex carb sources.
Although not regulated as a definition by the United States Food and Drug Administration (FDA), this calculation has been used as a rule of thumb by many health-conscious individuals like ourselves who care about the quality of carbs, as well as the impact that different carbs have on our overall blood sugar levels. It’s important to note that different individuals have varying responses to fiber and sugar alcohols, so if you’re looking to strictly limit your carb intake, work with your physician, registered dietitian, or diabetes educator to best determine what will be effective for your needs.
I personally like monitoring net carbs because doing so can help promote higher intake of dietary fiber found in complex carbs, which helps you stay full and may help reduce and control blood sugar levels. Additionally, you’ll be able to eat a variety of nutrient-dense foods that are rich in fiber and thus lower in total carbs when looking at net carbs (vs. low carb diets that often skip fruits and legumes altogether). Many individuals following a keto diet often consider counting net carbs since this diet consists of low carbs, moderate to high protein, and high fat, but doing so can be helpful for anyone trying to prevent or reverse chronic diseases such as diabetes. There isn’t a set threshold or limit for how much net carbs anyone should consume – it’s ultimately up to you depending on your individual macronutrient, calorie, or health needs.
What About the Stuff That’s Not Net Carbs?
As I mentioned earlier, there are some ingredients in food that aren’t necessarily your typical carbs: fiber, low calorie sweeteners, sugar alcohols, and glycerin.
Dietary fiber can be insoluble (does not dissolve in water) or soluble (dissolves in water). Insoluble fiber leaves your body unchanged and virtually has no effect on your body. Soluble fiber helps you stay full. Common sources of fiber include nuts, seeds, beans, whole grains, and fruits.
While the daily nutritional goals for dietary fiber outlined by the Dietary Guidelines for Americans are 25g to 28g of for adult-aged women and 31g to 34g for adult-aged men, more than 90 percent of women and 97 percent of men do not meet the recommended intakes for dietary fiber.
Low Calorie Sweeteners
High-intensity sweeteners are often used as sugar substitutes in food and beverages. They are many times sweeter than sugar, but contain few or no calories. Common examples of traditional high-intensity sweeteners include saccharin, aspartame, and sucralose. The FDA recognizes these as Generally Recognized as Safe (GRAS) and has established acceptable daily intake amounts.
A couple of other sweeteners that have recently become more popular include stevia and monk fruit extract. Stevia comes from a South American plant and is 200 to 300 times sweeter than table sugar. A GRAS notice has been submitted to the FDA for steviol glycosides, which are extracts that come from stevia plants that provide the sweetness. Monk fruit extract is 250 times sweeter than table sugar and comes from a small, round fruit from Asia.
Allulose is another “new” player in the sweetener space. Allulose is a simple carbohydrate that tastes like sugar and has the same texture, but with 90 percent fewer calories than table sugar. It is found in very small quantities in natural food sources like maple syrup, figs, and raisins. When you eat foods with allulose, the allulose is absorbed in the body but for the most part, leaves the body without being metabolized. Unlike other caloric sugars, allulose has no impact on blood glucose or insulin levels. Allulose is found in select better-for-you snacks like Munk Pack Keto Granola Bars and Keto Nut & Seed Bars.
Sugar alcohols also taste sweet like sugar (generally 25 to 100 percent of the sweetness of sugar), but do not contain as many calories or have the same impact that sugar would when it comes to carbs. Common types of sugar alcohols you’ll see on nutrition labels include sorbitol, xylitol, erythritol, maltitol, and mannitol – they all end in -ol.
But, before you go grab a bunch of sugar-free treats and candy off the shelf full of sugar alcohols, consider that excessive intake of certain sugar alcohols may cause undesirable gastrointestinal effects like bloating, gas, and diarrhea.
Vegetable glycerin is classified similarly to sugar alcohols and is counted on the nutrition label under total carbs. It’s absorbed, but not digested and used by the body for energy like sugar, so it doesn’t count as a ‘net carb’. However, glycerin is a very different ingredient from sugar alcohols and carbs from a functional, regulatory, and nutritional standpoint.
Unlike sugar alcohols, which are processed from starch, vegetable glycerin is made from fat. Functionally, vegetable glycerin it is not used as a sweetener but to keep moisture in food products, in the case of Munk Pack’s Keto Granola Bars.
How Do You Calculate Net Carbs?
Net Carbs = Total Carbohydrate – Dietary Fiber – Sugar Alcohols – Other Carbs That Are Not Metabolized (e.g. allulose, glycerin)
The math is relatively simple, so let’s break it down with an example.
You can find the nutrition facts label on the back or side panel of any packaged food product to do the math. The part that you’ll specifically be looking at is under ‘Total Carbohydrate’, which is found closer to the bottom of the label.
Take Munk Pack Keto Nut & Seed Bars for example. The nutrition panel below is for the Peanut Butter Dark Chocolate variety, which checks off all the boxes that we ‘health nuts’ often look for in a snack: plant-based, non-GMO, keto-friendly, and gluten free. Plus, they have a sweet and salty flavor that makes it hard to believe that you’re eating a better-for-you product.
This label* shows us the following data:
Total Carbohydrate: 15g
Dietary Fiber: 4g
Sugar Alcohols: 0g
The calculation is as follows: 15 – 4 – 0 – 8 = 3g of total net carbs.
Voila! This means that for every Munk Pack Keto Peanut Butter Dark Chocolate Nut & Seed Bar you eat, only 3g of net carbs are used by the body as true carbs (from nuts, seeds, and peanut butter in this case). The allulose and fiber have a much lower impact, if at all, on your body’s blood sugar levels as I’ve noted earlier. It’s important to also note that a nutritious product like this is already low sugar and low glycemic index – it only has 15g of total carbohydrates to begin with.
For whole foods such as avocados that do not have a nutrition label, you can calculate net carbs by looking up the nutrient composition in the USDA Food Data Central website which outlines the total carbohydrates and fiber content of any food item.
The Bottom Line
Instead of counting total carbs, try to make every carb count by carefully evaluating the quality of the carbs in your food sources. By choosing foods that are higher in fiber and lower in net carbs, you’ll be able to incorporate in more complex carbs that are more nutritious and reduce your overall intake of added sugars. Be sure to consult with your physician, registered dietitian, or diabetes educator to monitor your individual response to different carbs.
Comment below and let me know if looking at net carbs has helped you stay on track with your health goals! Do you prefer looking at total carbs, net carbs, both, or neither?
*Munk Pack recently updated their packaging to include allulose in the nutrition panel. Allulose was not originally featured in the nutrition panel due to FDA guidelines that allows allulose to be excluded from total sugar and added sugar counts on nutrition labels. When allulose is not in the nutrition panel of Munk Pack products, you can find the complete net carb calculation, including the amount of allulose in the bar, printed on each wrapper.
|↑1, ↑3||Howarth NC, Saltzman E, Roberts SB. Dietary fiber and weight regulation. Nutr Rev. 2001 May;59(5):129-39|
|↑2||De Vadder F, Kovatcheva-Datchary P, Goncalves D, Vinera J, Zitoun C, Duchampt A, Bäckhed F, Mithieux G. Microbiota-generated metabolites promote metabolic benefits via gut-brain neural circuits. Cell. 2014 Jan 16;156(1-2):84-96|
|↑4||U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2020-2025 Dietary Guidelines for Americans. December 2020. Available at https://www.dietaryguidelines.gov/|
|↑5||U.S. Food and Drug Administration. Additional Information about High-Intensity Sweeteners Permitted for Use in Food in the United States. Available at https://www.fda.gov/food/ingredientspackaginglabeling/foodadditivesingredients/ucm397725.htm|
|↑6||U.S. Food and Drug Administration. High-Intensity Sweeteners. Available at https://www.fda.gov/food/food-additives-petitions/high-intensity-sweeteners|
|↑7||Calorie Control Council. Allulose. Available at https://caloriecontrol.org/allulose/|
|↑8||Iida T, Hayashi N, Yamada T, Yoshikawa Y, Miyazato S, Kishimoto Y, Okuma K, Tokuda M, Izumori K. Failure of d-psicose absorbed in the small intestine to metabolize into energy and its low large intestinal fermentability in humans. Metabolism 2010; 59:206-214|
|↑9||Iida T, Kishimoto Y, Yoshikawa Y, Hayashi N, Okuma K, Tohi M, Yagi K, Matsuo T, Izumori K. Acute D-psicose administration decreases the glycemic responses to an oral maltodextrin tolerance test in normal adults. J Nutr Sci Vitaminol (Tokyo) 2008; 54:511-514|
|↑10||Mäkinen KK. Gastrointestinal Disturbances Associated with the Consumption of Sugar Alcohols with Special Consideration of Xylitol: Scientific Review and Instructions for Dentists and Other Health-Care Professionals. Int J Dent. 2016; 2016:5967907|
|↑11||U.S. Department of Agriculture. FoodData Central Database. Available at https://fdc.nal.usda.gov/ndb/|