What Are Net Carbs?

Not all carbohydrates affect blood sugar the same way. The concept of “net carbs” tries to distinguish between the carbohydrates that raise your blood sugar levels and the ones that don’t. To find net carbs, you subtract the amount of these carbohydrates, fiber and a family of alternative sweeteners known as sugar alcohols, from the total carbohydrate count.

Many people with diabetes are familiar with net carbs as a way to help control their blood sugar levels, as are those who count carbs for weight-loss plans such as the ketogenic diet (keto) or the Atkins diet. Emphasizing net carbs can encourage people to eat more fiber-rich foods while still keeping a close eye on their carbohydrate intake.

Not all experts agree if it’s preferable to keep track of net carbs instead of total carbs. And if you have diabetes, experimenting with these approaches — ideally in collaboration with your healthcare team — will help you decide which strategy works best for you.

“Some consumers and food manufacturers define it as total carbohydrates minus the amount of fiber and sugar alcohols in the product,” says Jill Weisenberger, RDN, CDCES, a Newport News, Virginia–based certified diabetes care and education specialist and author of Prediabetes: A Complete Guide, 2nd edition.

The idea is that net carbs account for the amount of carbohydrates in your diet that contribute to blood sugar, Weisenberger says. This makes keeping track of net carbs potentially helpful for people with prediabetes or diabetes, those following a ketogenic (keto) diet, and anyone watching their carb intake or blood sugar levels.

In the United States, it’s relatively simple to calculate the net carbs of many foods with a quick look at the Nutrition Facts panel. Under the line for total carbohydrates, the panel will list different specific subcategories of carbohydrates, including dietary fiber and sugar alcohol. Just subtract those two numbers from the total carb count.

The math is easy for most packaged foods, but for other ingredients it can be hard to pinpoint an exact way to calculate or account for fiber and sugar alcohols, says Amy Kimberlain, RDN, CDCES, a Miami-based certified diabetes care and education specialist. Fresh fruits and vegetables, other whole foods, and even some packaged foods may not have a nutrition label to reference.

Both dietary fiber and sugar alcohols are thought to have little or no impact on blood sugar, which is why those numbers aren’t included in a net carb count.

Fiber

Dietary fiber is a type of carbohydrate that the human body does not digest. It’s considered extremely healthy, and is mainly found in fruit, grains, legumes, and vegetables, especially when they are minimally processed. In theory, it has no impact on blood sugar.

“While fiber may not impact blood sugar directly, the idea for including fiber in meals is to allow for a more blunted response versus a straight spike or rise in blood sugar,” says Kimberlain. “In general, the more fiber a meal contains, the better.”

Sugar Alcohols

• Sorbitol
• Xylitol
• Lactitol
• Mannitol
• Erythritol
• Maltitol

There is definitely no one-size-fits-all answer to this question. It will depend on your health and dietary goals. If you’re on a low-carb diet like keto or Atkins, counting net carbs may allow you to enjoy a wider variety of nutrient-dense, fiber rich foods without disrupting ketosis or eating more carbs than the diet suggests.

For people with type 1 or type 2 diabetes who use insulin, the question is especially relevant. People with diabetes are usually taught to count the carbohydrates of snacks and meals to help determine how much rapid-acting insulin they should use before eating. For certain foods containing a very high percentage of fiber or sugar alcohols — such as avocados, beans, or processed low-carb breads, tortillas, and granola bars — the difference between net carbs and total carbs can be significant. That might mean a big difference in insulin dosing, which could lead to low or high blood sugar levels.

For people with diabetes, Weisenberger recommends counting total carbs or total carbs minus fiber, and Zanini and Kimberlain both have suggested counting total carbs to their clients. Some people with diabetes have good results counting net carbs, and some have good results counting total carbs, and some do something in between. Your own results may vary from one food to another.

“It’s important to understand how all foods can impact your blood sugar levels,” she says.

The best way to learn what works for you is to test your blood sugar frequently, keep track of what you’re eating, and share that information with a professional who can double-check your interpretation.

• Net carbs are a different way of tracking carbohydrate intake than counting total carbs. People who have diabetes or who are following a low-carb diet may prefer to count carbs this way, since they’re only counting the carbs that impact blood sugar.
• To calculate net carbs, subtract the whole amount of fiber and half or all of the amount of sugar alcohols from the amount of total carbs on the nutrition label. This gives you a lower number than the total carb count.
• Dietary experts don’t agree that one way of counting carbs is always better than the other. Some people with diabetes have great results from counting net carbs and others do well by counting total carbs.
• If you have diabetes, the best way to learn which style of carb counting is best for you is to regularly check your blood sugar, keep track of what you eat, and discuss your results with a healthcare professional.