Is zero net carbs really no carbs? Decoding the truth behind the label

October 17, 2025 •

4 min read

Over a third of American adults are trying to lose weight, and many turn to low-carb diets and products claiming “zero net carbs” to meet their goals. However, this widely used marketing term doesn't mean a food is completely carb-free..

Quick Summary

Uncover the deceptive truth behind “zero net carbs.” Understand the difference between net carbs and total carbs, the impact of fiber and sugar alcohols, and why this calculated figure can be misleading for those on low-carb diets.

Key Points

Net Carbs are a Marketing Term: The term "net carbs" is not officially regulated by bodies like the FDA and should not be confused with a food being truly carbohydrate-free.
The Calculation Is Imperfect: The formula subtracts fiber and some sugar alcohols from total carbs, but not all of these are completely non-digestible, meaning they can still affect blood sugar.
Sugar Alcohols Vary: The impact of sugar alcohols on blood sugar and digestion depends on the specific type used. Some, like erythritol, have minimal impact, while others, like maltitol, are partially absorbed.
Processed Foods are Problematic: Many low-carb processed foods rely on these calculations. It’s important to read the full ingredient list, as other components can still raise blood sugar.
Whole Foods Offer Clarity: Unprocessed foods like meat, eggs, and leafy greens are naturally low or zero in net carbs, offering a more transparent and nutrient-dense way to control carb intake.
Listen to Your Body: For those monitoring blood sugar, tracking individual responses is more reliable than relying solely on a net carb count from a food label.

The Truth Behind "Zero Net Carbs"

For years, low-carb diets like keto and Atkins have gained popularity for weight management and blood sugar control. As a result, food manufacturers have responded by flooding the market with products touting low or “zero net carbs.” While this label is a powerful marketing tool, it does not mean the food is completely devoid of carbohydrates. Instead, “net carbs” is an unofficial term referring to the amount of carbohydrates the body can fully digest and use for energy. This critical distinction, which is unregulated by the U.S. Food and Drug Administration (FDA), reveals that a “zero net carb” product can still contain carbohydrates. The number is a result of a mathematical calculation, not a statement of a food's complete carbohydrate absence.

How Net Carbs Are Calculated

To understand how a product can have carbohydrates yet claim "zero net carbs," it is crucial to understand the calculation method. The formula is as follows:

Total Carbohydrates - Dietary Fiber - (some) Sugar Alcohols = Net Carbs

This calculation hinges on the premise that not all carbohydrates impact blood sugar in the same way. The two main components subtracted from the total are fiber and sugar alcohols.

The Role of Fiber

Dietary fiber is a carbohydrate that the human body cannot fully digest or absorb. It passes through the digestive system relatively intact, providing bulk but having a minimal effect on blood sugar levels. In the net carb calculation, fiber is subtracted from the total carbohydrate count, which is why a food rich in fiber can have a significantly lower net carb count than its total carb count. For instance, a food with 20 grams of total carbohydrates and 10 grams of fiber would have only 10 grams of net carbs. This practice encourages the consumption of fiber-rich foods like vegetables, nuts, and seeds, which is generally beneficial for health.

The Complexity of Sugar Alcohols

Sugar alcohols are a family of alternative sweeteners used in many low-carb products to mimic the taste of sugar without the calorie or blood sugar impact. However, the effect of sugar alcohols on blood sugar varies by type. While some, like erythritol, have a minimal impact and can be fully subtracted, others, such as maltitol, are partially digested and still affect blood glucose levels. This nuance is often lost in the marketing claim. Furthermore, excessive consumption of sugar alcohols can lead to unpleasant side effects like gas, bloating, and diarrhea. When reading labels, it is important to be aware of the specific sugar alcohol used and how it may affect your body.

The Pitfalls of Net Carb Claims on Processed Foods

While net carb counting can be a useful tool for some, particularly those on ketogenic diets, it can also be misleading, especially with processed and manufactured products. The lack of regulatory oversight allows companies to make claims that may not reflect the full picture of a product's nutritional impact. Some processed goods use a high amount of fiber or sugar alcohols to create a low net carb value while still containing other ingredients that can raise blood sugar. For example, a protein bar might claim a low net carb count due to added fiber and sugar alcohols, but the ingredients list may reveal other carbohydrates that still affect blood glucose. People with diabetes, in particular, are advised by health organizations like the American Diabetes Association (ADA) to count total carbs and monitor their blood sugar response carefully when consuming products with added fiber or sugar alcohols.

Total Carbs vs. Net Carbs: A Comparison

To make informed decisions, understanding the key differences is essential.


Feature	Total Carbs	Net Carbs
Definition	Represents all carbohydrates in a food: sugars, starches, and fiber.	Represents digestible carbs after subtracting fiber and certain sugar alcohols.
Regulatory Status	Regulated by the FDA on nutrition labels.	Not legally defined; it's a marketing term.
Calculation	The full number listed on the nutrition label.	Requires a manual calculation from the nutrition label.
Primary Use	Standard nutrition tracking and consistent measurement.	Used by those on low-carb, keto, or Atkins diets.
Blood Sugar Impact	Accurately reflects all carbs with the potential to affect blood sugar.	Can underestimate blood sugar impact due to partial absorption of some sugar alcohols.
Reliance & Reliability	Consistent and regulated, providing a reliable measure.	Can be inconsistent and misleading, depending on the ingredients and types of sugar alcohols used.

Examples of Truly Zero or Negligible Net Carb Foods

While manufactured products often have caveats, some whole, unprocessed foods naturally contain zero or very low net carbs. These options are a reliable part of a low-carb diet.

Truly Zero-Carb Foods: These are primarily animal-based products and fats. Examples include meat, poultry, fish, eggs, olive oil, and coconut oil.
Negligible-Carb Foods: Some plant-based foods, while not zero-carb, have extremely high fiber content, resulting in a negligible net carb count per serving. Examples include leafy greens like spinach and lettuce, as well as celery and shirataki noodles.

Conclusion

Ultimately, while the “zero net carb” label is appealing, it does not mean a food is carbohydrate-free. It is a calculated figure that relies on subtracting non-digestible or partially-digestible components like fiber and sugar alcohols. For those following a low-carb diet, especially for health reasons like diabetes management, it is crucial to read the full nutrition facts panel and ingredient list carefully. The most reliable path is to prioritize whole, unprocessed foods, which naturally contain fiber and nutrients, over highly processed alternatives designed to meet a marketing claim. Always monitor your body’s unique response, and when in doubt, consult a healthcare professional. By understanding the difference between total and net carbs, you can make more informed choices that align with your health and wellness goals.

One resource that can provide additional context and guidance for those managing blood sugar is the American Diabetes Association's information on understanding carbohydrates: https://diabetes.org/food-nutrition/understanding-carbs/get-to-know-carbs.

Frequently Asked Questions

Total carbs are all the carbohydrates in a food, including sugars, starches, and fiber. Net carbs are a calculated figure that subtracts fiber and certain sugar alcohols from the total, representing the carbs that are most likely to affect blood sugar.

No. A product with "zero net carbs" can still contain carbohydrates and calories from other sources, like protein and fat. Eating unlimited amounts can still lead to weight gain or digestive issues, especially from excess sugar alcohols.

On a U.S. nutrition label, take the total carbohydrates and subtract the grams of dietary fiber. If sugar alcohols are listed, you can often subtract half their amount, though the impact varies by type. The exception is erythritol, which can be fully subtracted.

No. Different sugar alcohols have varying effects on blood sugar. Erythritol has a minimal impact, while maltitol is partially absorbed and can still raise blood glucose. This inconsistency is a major flaw in relying solely on net carb claims.

The term "net carbs" is a marketing term and has no legal or standardized definition, so the FDA does not regulate it. The FDA recommends using the total carbohydrates listed on the nutrition facts panel for clarity.

The American Diabetes Association suggests counting total carbs, as the impact of fiber and sugar alcohols can vary and is not always predictable. It is recommended to work with a healthcare professional to determine the best carb-counting strategy and to monitor blood sugar levels closely.

Truly zero-carb options include most animal products like meat, poultry, fish, and eggs. Certain fats and oils, such as olive oil and coconut oil, also have zero carbs.