Carbs vs. Net Carbs: What’s the Difference?

If you’re on the ketogenic diet or have diabetes, you probably know that limiting carbohydrates is the name of the game. However, it’s not necessarily as simple as tallying up the total carbs you consume daily.

The concept of “net carbs” adds another layer to carb counting. Don’t let the term scare you—we’re here to unravel the concept and explain the difference between “carbs” and “net carbs.” So, grab your calculator (or get your fingers ready), and let’s dive in. 

Why Is Counting Carbs Important on a Keto Diet?

Carbohydrates (carbs) are one of the three macronutrients that make up the foods we eat, along with protein and fat. They’re essential for providing energy to the body and are found in a wide variety of foods, including grains, legumes, fruits, milk, vegetables, and processed sugar.

Those following a keto diet drastically limit carbs and follow this macronutrient formula: 

• 60 to 75 percent of your daily calories from fat
• 15 to 30 percent of your daily calories from protein 
• 5 to 10 percent of your daily calories from carbs

That translates to about 50 grams of carbs daily. Keeping your carb intake super low shifts the body from burning carbs (its typical fuel source) to burning fat. This change in metabolic state is known as ketosis.

Counting your carb intake can make the difference between staying in ketosis or not. And why would someone want to stay in ketosis? There are several benefits, including weight loss, more stable energy, reduced need for insulin in those with diabetes, improved brain health, and reduced hunger.[*][*][*][*] 

Carbs vs. Net Carbs

“Carbs” refers to the total grams of carbohydrates in a food. This is the number found on a food’s nutrition label (or displayed on a food tracking app).

The total grams of carbs includes carbs from all sources (natural sugars, added sugar, starches, dietary fiber, and sugar alcohol).

“Net carbs,” sometimes called “impact carbs” or “digestible carbs,” refer to the number of carbs that are actually absorbed by the body. Let’s break this down further in the next section.

Understanding Net Carbs

The FDA doesn’t have an official definition of net carbs, so there may be some variations in how it’s defined and calculated. However, in general terms, net carbs refer to the carbs that remain after you subtract the grams of fiber from the total grams of carbs per serving. Some people also subtract sugar alcohols.

Here’s the formula so you can better visualize it: total carbs – (fiber + sugar alcohols) = net carbs.

The idea behind net carbs is rooted in the way your body digests certain types of carbs, namely fiber and sugar alcohols. 

• Fiber: Despite being classified as a carb, your body doesn't have the enzymes to break down fiber. Therefore, it remains (mostly) undigested and does not impact your blood glucose levels.[*]
• Sugar alcohols: Sugar alcohols are a type of carb that have a chemical structure similar to sugar. They taste sweet, but don’t contain actual sugar. Most types of sugar alcohols are only partially absorbed by the body.[*]

Because the body doesn’t fully absorb fiber and sugar alcohols, many experts state that they don’t meaningfully contribute to one’s total carb intake. For this reason, most people subtract them from the total carb count when calculating the net carb number. 

A Note on Sugar Alcohols

You’ll see sugar alcohols listed on nutrition labels as erythritol, xylitol, mannitol, lactitol, maltitol, sorbitol, isomalt, or glycerin. They’re commonly found in products labeled “sugar-free” or “no sugar added.”

Studies have shown that two to 90 percent of sugar alcohols are absorbed by the small intestine.[*]

In other words, the absorption of sugar alcohol varies widely depending on the type and person. Besides erythritol, most are capable of raising blood sugar and contributing to carb count at least slightly.

To play it safe, some people choose to count sugar alcohols in the net carb count. Others choose to subtract sugar alcohol grams from total carb grams when calculating net carbs. And others choose to subtract half of the sugar alcohol grams from the total grams of carbs.

The last option is based on the estimate that only about half of the sugar alcohol grams will be absorbed by the body.[*] Erythritol is an exception. If it’s the only sugar alcohol listed, then its carb grams can be completely subtracted from the total carb count.

Note: Some sugar alcohols are found naturally in small amounts in whole foods, but you only have to be mindful of synthetic sugar alcohols that are added to processed foods (which will be listed on the nutrition label, if present).

Is It Better to Count Total Carbs or Net Carbs on a Keto Diet?

There are pluses and minuses to both options. 

Counting net carbs on a keto diet will give you more food options, as a food previously considered too high in carbs might fit into your diet when considered from a net carb standpoint.

Counting net carbs also gives you a better idea of how that particular food might impact your blood sugar, which ties into how long you feel full and energized.

The downside is that because the body does absorb some fiber and sugar alcohols, knowing precisely how many carbs you’re taking in can be tricky.

Counting total carbs instead of net carbs can be the easiest way to guarantee that you stay within your carb range. The drawback? Eating this way can be more restrictive, as it limits your food options and portions.

Besides Low-Carb Diets, Why Might Someone Count Carbs?

Besides following a low-carb diet like keto, the other main reason people count carbs is because they have diabetes.

When someone has diabetes, counting carbs is a key strategy for keeping blood sugar levels steady because the carbs in foods break down into glucose (sugar) when digested.

The hormone insulin typically helps regulate a person’s glucose levels, but those with diabetes don’t use it effectively or make enough of it. So, these folks have to manage their blood sugar level through diet and, in some cases, taking supplemental insulin.

Since the body doesn’t fully absorb fiber and sugar alcohols, the carbs that accompany them largely don’t affect blood sugar levels. As such, some people with diabetes choose to count net carbs, rather than total carbs. Others prefer to count total carbs for more precision.

How to Calculate Net Carbs 

As mentioned above, the formula for calculating net carbs is: total carbs – (fiber + sugar alcohols) = net carbs. Note: As mentioned above, some people divide the sugar alcohol grams in half. 

With packaged foods, you can find all the information you need to calculate net carbs on the nutrition label.

As an example, let’s look at a Chocolate Sea Salt IQBAR, a vegan and keto protein bar that contains 10 grams of carbs, 8 grams of fiber, and zero sugar alcohols per bar. Here’s how the net carbs are calculated: 

10g total carbs – 8g fiber = 2g net carbs

With whole foods, simply look up the nutritional information online or use a food tracker app and plug it into the equation.  

The Bottom Line on Carb Counting

Phew—bet you didn’t know you were coming to math class today! While this might sound complicated, it’s pretty simple once you practice a few times, especially when dealing with whole foods and packaged foods without sugar alcohols (like IQBARs).