This part can get a little bit confusing in the beginning but gets easier with practice. Net carbs are the carbohydrates that our bodies can digest and turn into sugar, where total carbs include sugar, fiber or indigestible starch.

Fiber does not increase your blood sugar levels. It’s a type of carbohydrate that your body cannot digest, therefore you might subtract the fiber from the total carbohydrate (1).

There are two types of fibers:

  • Soluble fiber (dissolves in water). This type of fiber can help lower blood cholesterol and improve blood glucose control (2, 3)
  • Insoluble fiber (does not dissolve in water). This type of fiber can help promote regularity by making food move better through your digestive system and therefore help prevent constipation. Therefore you should be eating enough fiber.

Net carbs, or the carbs you can digest, are the ones we’re concerned with since too many will inhibit ketosis and may stall weight loss efforts.

Net Carbs Formula for Most Natural Foods

To calculate net carbs, you would subtract Fiber from the Total Carbohydrates on the nutrition label.

Net Carbs = Total Carbohydrates – Dietary Fiber

Some smart companies have already begun adding a net carbs line on the label, making this far easier to track.

However, sometimes you need to pay close attention to the nutrition label because it can be a bit confusing. Some food labels show total carbs whereas some show net carbs. It all depends on the country you live, the companies, and where the food is manufactured.

In some countries in Europe and Australia, they separate the fiber amount from total carbs (see image 1), so you don’t have to do the calculation. The carbohydrate amount in the label is also the net carbs.

In the US and Canada, most companies put the fiber included in the total carbs (see image 2), so you have to deduct the fiber from total carbs to get your net carbs.

Calculating net carbs

Here’s a tip: If total carbs minus fiber is less than zero (a “negative net carb”) then this means the fiber amount has already been subtracted from total carb, so what you see as the carb amount on the label is also your net carb. See image 3 below as an example of “negative net carb”.

negative net carb

Since there is no such thing as negative net carbs, the carbohydrate amount (26.2g per 100g) you see in image 3 is also the net carb.

Bottom line: you need to read the label carefully. It might be different depending on the country you live, whether the manufacturers are local or international and if the products are local or imported. If unsure, double check with other labels from other manufacturers of similar products or do your own research.

Calculating Net Carbs of Foods that Have Sugar Alcohols

A sugar alcohol is neither a sugar nor an alcoholic beverage. It doesn’t get you drunk despite having the word “alcohol” in its name. Sugar alcohols are organic compounds naturally found in fruits and vegetables and may be found in “sugar-free” or “no sugar added” products.

Some examples of sugar alcohol include mannitol, erythritol, sorbitol, isomalt, lactitol, xylitol, and maltitol.

The most common keto-approved sugar alcohol used in low carb recipes is erythritol.

Sugar alcohols are hard for our body to digest which is why consuming sugar alcohols in excessive amounts may cause digestive problems such as cramping, gas, and diarrhea.

Because sugar alcohols have less effect on blood sugar levels compared to standard sugar, this is one of the reasons why some experts suggest to subtract sugar alcohols amount completely from the total carbs to get your net carb.

They would say:

Net Carbs = Total Carbs – Fiber – Sugar Alcohols.

This formula is perfectly fine for most people. If sugar alcohol doesn’t affect you, yes you can subtract the whole amount. It is fine.

However, sugar alcohols are still a form of carbohydrate. Some of them might still affect the blood sugar levels for a few people (4, 5).

If you are on the ketogenic diet and you want to play it safe, you should count half of the sugar alcohol amount as carbohydrate. So the formula for calculating net carbohydrates will be:

Net Carbs = Total Carbs – Fiber – 1/2 Sugar Alcohols

Let’s look at this nutrition label as an example:

Deduct half sugar alcohol for net carbs

The product in the image above has 19g of total carbs, 2g of fiber and 15g of sugar alcohol. To play it safe, you might want to count half of the sugar alcohol as carbs, which is 1/2 * 15g = 7.5g

So the net carbs in this product will be:

Net Carbs = Total Carbs – Fiber – 1/2 Sugar Alcohols

Net Carbs = 19g – 2g – 7.5g = 9.5g

Conclusion: While all of this might seem confusing at first, all you need to remember is to keep it simple by remembering these 3 things:

  • Net Carbs = Total Carbs – Fiber
  • Read labels carefully, if not sure, do research.
  • Don’t consume too many sugar alcohols (just to play it safe).

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How to Calculate Net Carbs on keto

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