Understanding What Carbs Don't Count on Keto for Net Carb Success

January 2, 2026 •

4 min read

According to Medical News Today, a person on a ketogenic diet should consume up to 50 grams of net carbohydrates per day to stay in ketosis. To achieve this, it is crucial to understand what carbs don't count on keto, primarily dietary fiber and certain sugar alcohols.

Quick Summary

Net carbohydrates on a ketogenic diet are calculated by subtracting fiber and some sugar alcohols from the total carb count. These compounds are poorly digested, resulting in a minimal impact on blood sugar and allowing for more food options.

Key Points

Net Carbs Defined: Net carbs are the total carbohydrates minus fiber and most sugar alcohols, as these are not fully absorbed by the body.
Fiber is Indigestible: Dietary fiber is a carbohydrate that does not raise blood sugar, so it is always subtracted when calculating net carbs.
Sugar Alcohols Vary: Not all sugar alcohols are created equal; erythritol has a zero glycemic index, while others like maltitol can impact blood sugar more significantly.
Read Labels Carefully: Since "net carbs" are not FDA-regulated, scrutinize nutrition labels and ingredient lists on packaged keto products to avoid hidden carbs.
Prioritize Whole Foods: The safest and most reliable way to manage net carbs on a keto diet is to focus on whole, unprocessed foods like leafy greens, nuts, and avocados.

The Core Concept: Net Carbs

On the standard ketogenic diet, the goal is to severely restrict carbohydrate intake to force the body into a metabolic state called ketosis. However, not all carbohydrates affect your body in the same way. The term "net carbs" refers to the carbohydrates that are actually absorbed by the body and impact blood sugar levels. This is why calculating net carbs is a key practice for many keto dieters.

How to Calculate Net Carbs

The calculation for net carbs is straightforward: you take a food's total carbohydrates and subtract the grams of dietary fiber and (most) sugar alcohols.

Net Carbs = Total Carbs - Fiber - (most) Sugar Alcohols

For whole foods, the calculation is simpler, as they don't contain added sugar alcohols. For example, to find the net carbs in an avocado, you would look at the nutrition label, find the total carbs, and subtract the fiber. With packaged products, it is essential to read the ingredient list carefully to identify any added sugar alcohols.

Indigestible Carbs: Fiber and Sugar Alcohols

The Role of Dietary Fiber

Dietary fiber is a type of carbohydrate that our bodies cannot fully digest or absorb. It passes through the digestive system largely intact, contributing to gut health and satiety without raising blood glucose significantly. This is why fiber is subtracted from the total carb count when calculating net carbs. Including high-fiber, low-carb foods is vital for digestive regularity and overall wellness on a keto diet, which can sometimes be lacking in roughage.

Examples of keto-friendly, high-fiber foods:

Leafy greens (spinach, kale)
Broccoli and cauliflower
Avocado
Chia seeds and flax seeds
Nuts (almonds, pecans)

The Complex Case of Sugar Alcohols

Sugar alcohols, or polyols, are sweeteners that taste similar to sugar but are not completely absorbed by the body. They have a lower impact on blood sugar, but their effect can vary widely depending on the type. Some are nearly non-caloric and don't affect blood sugar at all, while others have a more pronounced effect.

Comparing Common Sugar Alcohols


Sugar Alcohol	Glycemic Impact	Keto Friendliness	Potential Side Effects
Erythritol	Zero glycemic index	Very high; can subtract entirely from total carbs.	Minimal; generally well-tolerated.
Xylitol	Low glycemic impact; partially absorbed	Good; subtract half the grams from total carbs.	Can cause digestive issues in larger amounts.
Maltitol	Moderate glycemic impact; index up to 52	Limited; subtract half the grams with caution.	More likely to cause digestive distress and blood sugar spikes.
Sorbitol	Low glycemic impact; partially absorbed	Good; subtract half the grams from total carbs.	Can have a laxative effect in excess.

It is crucial to note that the term "net carbs" is not officially regulated by the FDA, and some companies may use it to make processed products appear more keto-friendly than they are. Always check the ingredient list for sugar alcohols and adjust your calculations accordingly.

Whole Foods vs. Processed Keto Products

While counting net carbs in packaged products can be beneficial, focusing on whole, unprocessed foods is the most reliable way to stay in ketosis. Natural sources of fiber, like non-starchy vegetables, berries, and nuts, provide essential nutrients without the risk of hidden sugars or artificial ingredients found in many packaged keto snacks.

Pitfalls of Processed Keto Snacks

Misleading Labels: Some "keto" products rely heavily on sugar alcohols like maltitol, which can stall weight loss or cause digestive upset due to its higher glycemic impact.
Perpetuating Cravings: Relying on sweet-tasting sugar alcohols can hinder your ability to break a dependency on sweets, making the diet more difficult long-term.
Nutrient-Poor: Many processed keto products offer little nutritional value beyond the fats and proteins, unlike whole foods which are rich in vitamins and minerals.

For a more sustainable and healthy keto journey, prioritizing whole foods is the safest approach. When choosing a packaged item, scrutinize the nutrition label and ingredient list carefully. You can find more information on mindful carbohydrate choices from reputable sources like the American Diabetes Association.

Conclusion

Understanding which carbs don't count on keto, primarily fiber and certain sugar alcohols, is key to successfully managing your intake through net carb calculation. By subtracting these poorly-digested compounds, you can enjoy a wider variety of foods while remaining in ketosis. However, a mindful approach is necessary, especially with processed products, where relying on whole, nutrient-dense foods remains the safest and healthiest strategy. Always pay close attention to labels and listen to your body's response to different sweeteners. This knowledge empowers you to make smarter dietary choices and build a sustainable ketogenic lifestyle.

Frequently Asked Questions

Total carbs represent all carbohydrates in a food, including sugars, starches, and fiber. Net carbs are only the carbohydrates that are digestible and impact blood sugar. On a keto diet, you count net carbs by subtracting fiber and most sugar alcohols from the total carb count.

Yes, all dietary fiber is generally subtracted when counting net carbs for keto. Since the body cannot fully digest or absorb fiber, it does not raise blood sugar levels in the same way as other carbohydrates.

Not all sugar alcohols should be subtracted fully. Erythritol has a negligible impact on blood sugar and can be fully subtracted. However, other sugar alcohols like maltitol are partially absorbed and have a more significant glycemic effect, so only half should be subtracted, or they should be limited entirely.

Great sources of fiber that don't count towards net carbs include leafy greens, broccoli, cauliflower, avocado, and various nuts and seeds. These foods offer significant fiber and nutritional value while being low in net carbs.

Some keto products use sugar alcohols like maltitol, which have a higher glycemic index and can cause blood sugar spikes, especially in large quantities or in sensitive individuals. The non-regulated nature of 'net carbs' on labels can sometimes be misleading.

While fiber is beneficial, consuming excessive amounts can cause digestive issues like bloating, gas, or stomach discomfort. It's best to increase your fiber intake gradually and ensure you are also drinking plenty of water.

While some experts advise counting total carbs for stricter control, especially for those sensitive to sugar alcohols, counting net carbs is the standard practice for many keto dieters. This allows for a more varied diet while still effectively managing carb intake for ketosis.