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.

The term “net carbs” has no legal definition and isn’t recognized by nutrition authorities like the U.S. Food and Drug Administration (FDA) or American Diabetes Association (ADA).

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.

While you might see the term “net carbs” on some food packaging, it will not be on the Nutrition Facts label.

Food companies use the term to appeal to those who follow the keto diet and other low-carb diet trends, but because it isn’t regulated, you should probably take net carb claims with a grain of salt and do the math yourself.

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.”

There are two types of dietary fiber: soluble and insoluble fiber. Soluble fiber feeds good gut bacteria, and is found in foods such as apples, barley, and oats. Insoluble fiber helps promote softer and regular stools, and is found in foods such as whole-wheat flour, vegetables, and berries.

Sometimes food packaging lists the amount of each of these different fibers, but sometimes it does not. Both types of fiber are believed to help lower blood sugar levels in the long-term, but you may find that your body tolerates one type of fiber better than the other.

Sugar Alcohols

Sugar alcohols are used as an alternative sweetener in many packaged low-carb foods. They can occur naturally in foods, but most are produced industrially.

Foods that are labeled “sugar-free,” including hard candies, cookies, chewing gum, and soft drinks may contain sugar alcohols.

Sugar alcohols are carbohydrates that are hybrids between sugar molecules and alcohol molecules. They are generally thought to have zero calories and zero blood sugar impact. Examples of sugar alcohols include:

Sorbitol
Xylitol
Lactitol
Mannitol
Erythritol
Maltitol

Sugar alcohols are converted to glucose more slowly than other types of carbohydrates, and they require little to no insulin to be metabolized.

“This creates a minimal impact on blood glucose,” says Lori Zanini, RD, CDCES, a certified diabetes care and education specialist based in Los Angeles, and author of Eat What You Love Diabetes Cookbook. “When calculating net carbs, individuals can subtract half or all of the amount of sugar alcohols from the total carbohydrates.”

In many ways, sugar alcohols such as erythritol are attractive alternatives to sugar and often quite helpful in supporting people’s health and nutrition goals when used in moderation. When eaten in excess, sugar alcohols can cause gas, bloating, and diarrhea. And higher blood levels of erythritol have been associated with a greater heart attack and stroke risk.

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.

While it might seem logical that insulin users should focus on net carbs, because only net carbs raise blood sugar levels, the reality is a bit more complicated. The American Diabetes Association states that some types of fiber and sugar alcohol can affect blood glucose levels, an effect that can’t be predicted using the information on a Nutrition Facts panel. The organization recommends using total carbs to determine insulin doses, and then monitoring blood sugar levels closely.

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 also important to consider what foods are paired with the carbohydrates you’re eating,” says Kimberlain. Fiber, protein, and fats can help stabilize glucose levels by slowing down the digestion of carbs.

“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.

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