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Calculate net carbs for keto and low-carb diets by accounting for fiber and sugar alcohols
Fiber is subtracted 100% from total carbs
Different sugar alcohols have different impacts on blood sugar
per day for optimal ketosis
per day for most people in ketosis
per day for general low-carb diets
Net carbs represent the carbohydrates that are actually digested and absorbed by your body, impacting blood sugar levels. The concept is essential for ketogenic and low-carb diets because it helps identify which carbs will affect ketosis.
Fiber is subtracted because it passes through your digestive system without being broken down into glucose. Sugar alcohols have varying impacts: erythritol has virtually no effect on blood sugar, while others like maltitol and xylitol have about 50% the impact of regular sugar.
Important Note:
Different countries label foods differently. In the US, fiber is included in total carbs, so you subtract it. In Europe and Australia, carbs are already listed as "net" (excluding fiber), so no subtraction is needed.
| Sugar Alcohol | Impact on Net Carbs | Notes |
|---|---|---|
| Erythritol | 0% | Not absorbed; no blood sugar impact |
| Xylitol | 50% | Moderate absorption; some impact |
| Maltitol | 50% | Higher glycemic index; use cautiously |
| Sorbitol | 50% | Can cause digestive issues |
| Mannitol | 50% | Poorly absorbed; laxative effect |
| Isomalt | 50% | Partially absorbed |
Check if your country includes fiber in total carbs or lists it separately
Hidden carbs in sauces, dressings, and seasonings add up quickly
It has zero impact on blood sugar and net carbs
Vegetables and proteins are naturally low in net carbs
Some people are more sensitive to certain sugar alcohols
Apps can automatically calculate net carbs for you
Fiber is a type of carbohydrate that your body cannot digest. It passes through your digestive system without being broken down into glucose, so it doesn't affect blood sugar levels or interfere with ketosis.
No, only erythritol can be subtracted completely. Most other sugar alcohols are partially absorbed and should only be counted at 50% (subtract half). When in doubt, be conservative and count more rather than less.
If the type isn't specified, it's safest to assume it's not erythritol and use the 50% rule. Subtract half the sugar alcohol grams from your total carbs. This conservative approach helps ensure you stay within your carb limits.
On a ketogenic diet, you track net carbs. The typical recommendation is to stay under 20-50g of net carbs per day to maintain ketosis. However, some people prefer to track total carbs for simplicity.
While fiber doesn't count toward net carbs, excessive fiber intake can cause digestive discomfort. Aim for 25-35g of fiber daily from whole food sources like vegetables, nuts, and seeds.
Many keto-friendly products use fiber and sugar alcohols (especially erythritol) to add bulk and sweetness without impacting net carbs. Always check the ingredient list to see what's being subtracted.
Erythritol is unlikely to affect ketosis. However, maltitol and other sugar alcohols have a higher glycemic index and may impact blood sugar in some people, potentially affecting ketosis if consumed in large amounts.
Net carb calculations are estimates based on average absorption rates. Individual responses vary, especially with sugar alcohols. Monitor your blood glucose or ketones if you want precise data on how specific foods affect you personally.
Medical Disclaimer: This calculator is for informational purposes only. Before starting any new diet, especially a ketogenic diet, consult with a healthcare provider or registered dietitian. Individual carbohydrate tolerance varies, and what works for one person may not work for another.