Unveiling the Truth About Net Carbs

In some circles “carbs” has become a dirty word, something to be avoided at all costs. Carbs, or carbohydrates, are macronutrients that provide 4 calories per gram and have long been a part of the human diet.1,2,3 However, following certain emerging dietary trends, such as keto and Paleo, requires removing a majority of carbohydrates from the diet. Whether you “love ’em”or “leave ’em,” it is important to understand how these macronutrients are listed on food labels in order to make the choices that best fit into your own lifestyle.

What are net carbs?

Not all carbs are processed in the body the same way. Some carbs have a reduced or no caloric value. This is true for fiber. Other carbs are sugar alcohols and are digested in a different way and thus have a different caloric value and affect blood sugar differently from other sugars.2 With this in mind, some companies selling low-carbohydrate foods have chosen to describe the carbohydrate content with the term “net carbs”—a term not yet officially defined—to describe the quantity of carbohydrate after subtracting fiber and sugar alcohols.4 The idea of net carbs is to identify the net impact that carbohydrates have on the body. However, because the concept of “net carbs” is not a term defined, or regulated, by the Food and Drug Administration (FDA), this term is not reliable. What is important is to understand the various types of carbohydrates in your diet and how they differ from one another.

Carbs are plentiful in foods such as baked goods, sugary foods, breads, grains, fruits, and starchy vegetables. While it would be beneficial for almost everyone to remove carb-heavy foods like pastries, soda, and candy from their diet, other carbs that come from whole grains, fruits, and vegetables are important to a well-rounded diet. One of the reasons those types of foods are beneficial is that they provide indigestible fiber, which also helps to provide support for intestinal mobility and removal of waste from the body.5 Additionally, insoluble fiber, such as that found in bran, has essentially no caloric value because it is not digestible. Soluble fiber does get partially absorbed and provides about 2 calories per gram, instead of 4 calories, as found in other carbohydrates.1

Indigestible fibers support the healthy functioning of the body. Insoluble fiber helps move waste through the intestine, often referred to as laxation. This helps prevent occasional constipation,5 which may be a problem with a low-carbohydrate lifestyle. On the other hand, soluble fiber swells up after consumption and provides cushioning in the intestine and also helps to bind unwanted components and cholesterol.6,7 Soluble fiber also may act as a prebiotic, supporting the growth of healthful bacteria in the intestine.8 The combination of insoluble and soluble fiber are two key components in helping the intestine to be functional.

Breaking down net carbs

For those counting carbs, reading labels is a way of life. It’s important to remember that when carbohydrates are listed on a label, they include the starchy and sugary carbs as well as fiber, so look for foods that provide fiber without high levels of sugars and starch.

A new development in food labeling regulations is that the FDA has redefined what specific ingredients can be listed as dietary fiber based on what the FDA has determined can be supported by specific, scientifically substantiated health benefits.9 While there is the possibility for other fibers to be added in the future, there are now indigestible fibers that would not be identified on the label as fiber if they were not on the FDA’s approved list, which makes the concept of net carbs even more difficult to justify. 


  1. Slavin J et al. Carbohydrates. Advances in Nutrition. 2014;5(6):760-761.
  2. Holesh JE et al. Physiology, Carbohydrates. [Updated 2018 Sep 12]. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2018 Jan. https://www.ncbi.nlm.nih.gov/books/NBK459280/. Accessed October 5, 2018.
  3. FDA Interactive Nutrition Facts Label.  https://www.accessdata.fda.gov/scripts/InteractiveNutritionFactsLabel/factsheets/Total_Carbohydrate.pdf. Accessed October 5, 2018.
  4. FDA Code of Federal Regulations Title 21, Volume 2. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=101.9&SearchTerm=nutrition%20label. Accessed October 5, 2018.
  5. Dhingra D et al. Dietary fibre in foods: a review. J Food Sci Tech. 2012;49(3):255-266.
  6. Gunness P et al. Mechanisms underlying the cholesterol-lowering properties of soluble dietary fibre polysaccharides. Food Funct. 2010;1(2):149-155.
  7. Sima P et al. β-glucans and cholesterol (Review). Intl J Molec Med. 2018;41(4):1799-1808.
  8. Simpson HL et al. Review article: dietary fibre–microbiota interactions. Alimentary Pharmacology & Therapeutics. 2015;42(2):158-179.
  9. FDA Questions and Answers on Dietary Fiber. https://www.fda.gov/food/labelingnutrition/ucm528582.htm. Accessed October 5, 2018. 

Submitted by the Metagenics Marketing Team

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