What are “Net Carbs” and Do They Count the Same?

by Jenna Braddock
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What are “Net Carbs” and Do They Count the Same?

You may have heard about “net carbs,” but what exactly is the meaning and significance behind them? The concept of net carbs became popular with the emergence of the Atkins Diet, which instructed individuals to calculate net carbs by subtracting fiber and sugar alcohols from the “total carbohydrates” amount on the Nutrition Facts panel.

Example:
Total carbohydrates = 20 g
Fiber = 5 g
Sugar alcohols = 2 g
20 – 5 – 2 = 13 g net carbs

The theory behind this is that fiber and sugar alcohols do not significantly affect blood sugar and therefore don’t “count” like other sources of carbs. Although this may seem like a sound theory to some, it is not entirely accurate. In order to fully understand the relevance of the net carb concept, it is important to first understand the functions of carbohydrates, fiber and sugar alcohols.

WHAT ARE CARBOHYDRATES?

All macronutrients (think: protein, fat, carbohydrates) give the body energy to fuel it through all sorts of activity, from a serene nap to a heart-pounding mile run. While protein and fat aid in a variety of processes such as cell structure, function and maintenance, the main role of carbs is to provide the body with fuel. Carbs are more readily broken down compared with fats and protein.

All carbs are converted into glucose (a sugar) during digestion and then flood the bloodstream. Your body then has to decide to use glucose for energy or store it as glycogen (a starch) or fat. Since you have a limited capacity to store glucose as glycogen, much of the unused glucose will likely be stored as fat. Since insulin helps your body use and store glucose, it’s believed that if you can keep insulin levels low, it will help your body burn fat instead of storing it. This is the theory behind monitoring blood sugar levels for weight management purposes, but it is difficult to determine the blood sugar levels that will lead to fat storage because everyone’s carbohydrate needs are unique.

WHERE DO “NET CARBS” COME IN?

How fast you process carbohydrates depends on the type of carbohydrates you’re eating. The more simple in nature a carbohydrate is, the quicker it is metabolized. Simple sugars (think: candy, syrup or soda) are digested really quickly so they rapidly spike your blood sugar. In contrast, vegetables and whole grains contain fiber, a type of carbohydrate that is harder to digest. As a result, they won’t spike blood sugar and insulin quite as quickly or sharply. The concept of “net carbs” focuses attention on carbs that increase blood sugar and insulin more quickly.

FIBER

Fiber is a type of carb that isn’t fully broken down during digestion and therefore does not provide energy (or calories). This means that it has little to no impact on blood sugar levels and why it is subtracted from the total grams of carbs.

There are two types of fiber that have different roles.

  • Insoluble fiber is not absorbed or broken down by the body, and it aids in removing waste from the intestinal tract while providing bulk and softness to stools to prevent constipation.
  • Soluble fiber is also not absorbed by the body, but it dissolves to become a gummy substance that helps to regulate blood sugar by slowing the absorption of glucose. It is also responsible for helping to lower cholesterol.

The American Heart Association recommends that adults consume 25–30 grams of total fiber per day as way to promote overall wellness and a healthy heart. Good sources of fiber include whole grains, fruits, vegetables, beans, nuts and seeds.

Don’t just trust a “net carb” label on a food. Make sure you read the ingredients list to see how many grams of fiber that food contains.

SUGAR ALCOHOLS

Ever wonder how your local grocery store can carry “sugar-free” candies? Chances are these products contain sugar alcohol to provide the sweetness of sugar with fewer calories. There are many different types of sugar alcohols, and they each affect the body differently. Many of these sugar alcohols have been studied in research but not extensively. The available research even suggests that they have unpredictable effects on blood sugar, and it’s generally considered that they do raise blood sugar.

The issue with the net carbs concept is that sugar alcohols are generalized into one category when they are all very different. To know which sugar alcohols are in a food or beverage, you can check the ingredients listed on the packaging. The following are common sugar alcohols used in food and beverage production:

  • Xylitol
  • Sorbitol
  • Mannitol
  • Maltitol
  • Lactitol
  • Erythritol
  • Glycerol
  • Isomalt
  • Hydrogenated starch hydrolysates

By the way, eating too much sugar alcohols (more than 10 grams per day) isn’t recommended since they can cause tummy issues.

THE VERDICT

There isn’t a legal definition of “net carbs,” and the Food and Drug Administration does not recognize claims that involve net carbs as legitimate. In theory, net carbs are the amount of carbs from your food that can affect your blood sugar levels. Since we already discussed that sugar alcohols could impact blood sugar levels, it doesn’t seem like net carbs is the most reliable approach for managing carbohydrate intake.

When you see a net carb claim on a food label, this is just a marketing technique. This claim does not hold significant value in most cases. It is important to evaluate the Nutrition Facts panel for the total carbohydrate content as well as the other nutrient content such as total calories, protein, fiber and fat.

Individuals living with diabetes are often advised to subtract fiber from their foods’ total carbs in order to determine the amount of carbs that their body will absorb. This is important for them to know because their bodies have difficulty absorbing glucose. The American Diabetes Association also advises individuals with diabetes to count half the amount of sugar alcohols as carbs. For example, a sugar-free snack with 6 grams of sugar alcohols would count as 3 grams of carbs.

For the general population, I encourage people to simply focus on including more naturally high-fiber foods to achieve the recommended 25+ grams a day, as we are certain a high-fiber diet is connected to overall better health and weight. High-fiber foods will have a lower impact on blood sugar levels and will also help keep you fuller and more satisfied longer after meals.

Do you use “net carbs”? If so, share your experiences in the comments below.

Credit to Devyn Chadwell, University of North Florida Dietetic Intern and Graduate Student

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  • Rachel

    I’m not sure what the author means exactly by saying that the FDA doesn’t recognize or permit claims based on net carbs, because plenty of food producers seem to at least calculate and promote CALORIE COUNTS based on it (with no disclosure, btw). In the US, I buy several products that the nutritional information on the label is CLEARLY adjusted based on net carbs. For instance, go to a well-stocked grocery store and look at bags of dry beans. Chances are you will find at least one bag or brand that calculates the calorie count as protein grams *4 + (total carb grams – fiber grams) *4 + fat grams *9. And to boot, there is no disclosure anywhere on the label telling consumers that the calories have been calculated in this non-standard way. La Tortilla Factory sells a “high fiber low carb” tortilla that they count this way, and Boca burgers also appear to calculate their nutritional info this way. It bothers me in a small way (as a calorie thing, not an insulin thing) since it’s not standardized and not disclosed, and could be misleading for some people. Every day I eat probably 35-45g of fiber (I just have a longstanding preference for lots of beans and fruit) so it’s 120-180 calories that are kind of mysteriously / inconsistently counted for me. That adds up over time.

    • Paul Kopalek

      It’s still counted inconsistently. It makes the carb tracking just about useless. It would be nice if they at least offered a “don’t count fiber toward calories” option.

  • Andrea

    The definition of net carbs that I use, based on more recent (non-Atkins) readings, only subtracts fiber from total carbs. That still seems valid given what’s written in this article.

    • And I sure wish MFP allowed this option. For those doing something like following a Ketogenic diet, it’s worse than useless to track total carbs without subtracting fiber. I’m targeting 25 grams non-fiber carbs total per day. Seeing the total carbs only makes it look like I’m way over and/or discourages me from eating fiber.

      • Clea Zolotow

        Try the FOODFASTFIT add on to Chrome, it calculates the net carbs for you.