What Factors Cancel Out Net Carbs?

November 19, 2025 •

4 min read

While the term "net carbs" has no legal definition from the FDA, it has become a cornerstone of many low-carb and ketogenic diets. To understand what cancels out net carbs, you must first know that it is a calculation based on total carbohydrates minus certain indigestible components.

Quick Summary

This article explains how indigestible carbohydrates, such as fiber and sugar alcohols, are subtracted from total carbs to determine a food's net carb count. We detail the science behind this calculation, which is key for managing carb intake on low-carb eating plans.

Key Points

Fiber is subtracted: Dietary fiber is the primary component that reduces net carbs because it is indigestible and does not significantly raise blood sugar.
Sugar alcohols play a role: Some sugar alcohols, like erythritol and xylitol, are also subtracted from total carbs due to incomplete absorption.
Not an official metric: The term "net carbs" is not officially regulated by organizations like the FDA, but it is widely used in low-carb diets.
Calculation is simple: The formula is Total Carbs minus Fiber and partially or fully subtracted sugar alcohols.
Focus on high-fiber foods: Emphasizing whole, unprocessed foods naturally high in fiber is a reliable strategy for keeping net carbs low.
Pairing matters: Eating carbs with protein and healthy fats can also help mitigate blood sugar spikes.

The Science Behind Net Carbs: What Gets Subtracted?

Net carbs represent the digestible carbohydrates that actually impact your blood sugar levels and provide calories. Not all carbohydrates are created equal; some pass through your digestive system without being fully broken down and absorbed. The factors that are subtracted from total carbohydrates to get the net carb value are dietary fiber and sugar alcohols.

Dietary Fiber: The Primary Net Carb Reducer

Dietary fiber is a type of carbohydrate from plants that your body cannot fully digest. Since the human digestive system lacks the necessary enzymes to break down fiber, it passes through largely unchanged. This means it has a minimal impact on blood sugar and is often counted as having zero net carbs. Incorporating high-fiber foods is a key strategy for lowering the net carb content of a meal.

Types of Fiber:

Soluble Fiber: This type of fiber dissolves in water and is fermented by gut bacteria. While it may have a minor impact, it is still largely considered indigestible and is subtracted during net carb calculations. Foods rich in soluble fiber include oats, nuts, and beans.
Insoluble Fiber: Also known as dietary fiber, this passes through the body without being digested at all, providing no energy. Sources include whole-grain products, vegetable skins, and seeds.

Sugar Alcohols: The Sweet Subtractors

Sugar alcohols, such as erythritol, xylitol, and mannitol, are sweeteners commonly used in low-carb products. Their chemical structure is different from regular sugar, which makes them either partially or entirely indigestible. This incomplete digestion results in fewer calories and a lesser effect on blood sugar compared to sugar.

Rules for Sugar Alcohols:

Full Subtraction: Erythritol is a sugar alcohol that is almost entirely indigestible, so its total grams are often completely subtracted from the total carb count.
Partial Subtraction: Other sugar alcohols, like maltitol and xylitol, are only partially absorbed. For these, it is common practice to subtract only half of their gram count from the total carbohydrates.

How to Calculate Net Carbs Effectively

Calculating net carbs requires looking at the nutrition facts label. While the process is straightforward, different definitions and product formulations can lead to confusion. It is important to remember that this calculation is not standardized by the FDA in the United States, so you must rely on the labeled information.

Step-by-Step Guide:

Find the Total Carbohydrates: Look for the "Total Carbohydrate" line on the nutrition label.
Locate the Dietary Fiber: Find the "Dietary Fiber" listed under total carbohydrates.
Check for Sugar Alcohols: Note if any sugar alcohols (like erythritol, xylitol) are listed separately.
Perform the Subtraction: The basic formula is: Net Carbs = Total Carbs - Fiber - (Sugar Alcohols / 2) (or fully subtract erythritol).

Comparison Table: Total Carbs vs. Net Carbs

This table illustrates the difference in calculation for common low-carb and high-carb foods.


Food Item (per serving)	Total Carbs (g)	Dietary Fiber (g)	Sugar Alcohols (g)	Net Carbs (g)
Avocado (1/2)	8.5	6.7	0	1.8
Broccoli (1 cup, chopped)	6	2.4	0	3.6
Chia Seeds (2 tbsp)	12	10	0	2
Atkins Bar (with maltitol)	23	9	11	8.5 (23 - 9 - 5.5)
White Bread (1 slice)	14	1	0	13
Plain White Rice (1 cup)	45	0.6	0	44.4

Strategic Food Choices for Lower Net Carbs

Knowing what reduces net carbs allows for strategic meal planning, particularly for those on diets like keto or for managing blood sugar. Focusing on whole, unprocessed foods naturally rich in fiber is the most reliable approach.

Load up on Non-Starchy Vegetables: Leafy greens like spinach, kale, and arugula, as well as broccoli and cauliflower, are excellent, low-net-carb options.
Incorporate Healthy Fats and Protein: While they do not directly cancel out carbs, eating healthy fats (e.g., avocado, olive oil) and protein (e.g., eggs, meat) alongside carbs can slow down absorption and help manage blood sugar response.
Use Low-Carb Flours and Alternatives: Swap high-carb flours for alternatives like almond or coconut flour, and use vegetables as substitutes for staples like pasta or rice.

Conclusion: Navigating the Nuance of Net Carbs

In summary, the factors that "cancel out" net carbs are dietary fiber and, to a lesser extent, sugar alcohols. These components are subtracted from a food's total carbohydrate count because they are not fully digestible and have a minimal impact on blood glucose levels. While the concept of net carbs is not officially regulated by health organizations like the FDA, it is a practical tool for individuals following specific dietary plans such as the ketogenic diet. The most effective way to manage your net carb intake is to focus on nutrient-dense, high-fiber foods, while being mindful of sugar alcohols and highly processed carbohydrates.

Sources

American Diabetes Association. "Get to Know Carbs." Diabetes.org.
UCLA Health. "Net carbs are carbs minus fiber and sugar alcohols." UCLAHealth.org.

Frequently Asked Questions

Generally, yes. Both soluble and insoluble fiber are considered indigestible for net carb calculation purposes. Insoluble fiber passes through untouched, while soluble fiber is fermented by gut bacteria, but neither contributes significantly to blood sugar in the same way as digestible carbs.

No. The absorption rate varies among sugar alcohols. Erythritol, for instance, is almost fully subtracted, while others like maltitol are only partially subtracted (typically by half) from the total carbs to get the net carb count.

You should use the on-package information with caution. Since there is no legal definition of "net carbs" from the FDA, different companies may use different calculation methods. It is more accurate to use the total carbohydrates, fiber, and sugar alcohol numbers to do your own calculation.

Total carbs is the total amount of all carbohydrates in a food, including sugars, starches, and fiber. Net carbs are the total carbs minus the indigestible components (fiber and sugar alcohols), representing the carbs that are actually absorbed by the body.

Protein and fat do not literally cancel out carbs, but they can help regulate their impact on blood sugar. Consuming carbs with protein and fat slows digestion, which leads to a more gradual rise in blood sugar instead of a rapid spike.

Naturally low-net-carb foods are those with a high fiber content relative to their total carbohydrates. Examples include leafy greens (spinach, kale), avocado, chia seeds, broccoli, and cauliflower.

For those on low-carb diets like keto, counting net carbs is the goal because it focuses on the digestible carbs that affect ketosis. However, some nutritionists recommend focusing on total carbs for general health, as some fiber and sugar alcohols are still partially metabolized or can affect gut health differently.