Understanding Net Carbs on the Ketogenic Diet

If you’re new the keto diet, you’re probably asking yourself, what are net carbs, and why should I care? Once you start a keto diet, carbohydrates are just about the primary thing you check when watching a food’s nutrition label. And knowing the way to calculate net carbs is vital to your success.

Usually, there’s more to the label than only total carbohydrates. Fiber, sugar, sugar alcohols — they’re all listed under carbohydrates. What do they mean, and which of them do you have to concentrate on so you don’t re-evaluate your daily carb limit?

The key to deciding carb count is calculating a food’s net carbs: the carbs in food that impact your blood glucose. Manufacturers came up with the term “net carbs” within the early 2000s when low-carb diets began to catch on. But there’s no official definition of net carbs, and therefore the net carb calculates labels are often deceiving.

When you’re on a keto or low-carb diet, every gram of carbohydrate you eat counts, so it’s essential to understand the way to track net carbs accurately. This guide explains what net carbs are, why net carbs matter, and the way to calculate net carbs for yourself.

What Are Net Carbs?

Net carbs are the carbohydrates in the food that you can digest and use for energy. On a keto diet, starches and sugars enter the body, as well as tons of other sorts of carbohydrates like insoluble fiber. However these other carbs don’t have any energy value or impact on your blood glucose, so you don’t count them towards your daily keto carbohydrate limit.

Fiber is a kind of carbohydrate from plants that the human gastrointestinal system can’t process. Your body doesn’t have the enzymes to break down fibre, so it passes through your digestion unchanged. This means on keto, fiber has zero net carbs and 0 calories.

Sugar alcohols like xylitol and erythritol taste sweet, but their molecular structure is slightly different from that of sugar molecules, which leaves tons of sugar alcohols either partially or entirely indigestible by humans.

Note that certain sugar alcohols do impact your blood glucose, and you ought to factor them into your keto carb count if you eat a very large amount. For details, see the “How to calculate net carbs (including sugar alcohols)” section below.

Why Net Carbs Matter on Keto?

Net carbs are super important on keto. Most people do better with some carbs, which is why experts suggest a cyclical keto diet with one carb refeed day every week. Excess carbs, however, and particularly refined carbs like starches and sugars, may:

  • Spike your blood glucose
  • Contribute to inflammation
  • Trigger food cravings
  • Disrupt your hormones
  • Mess together with your gut bacteria
  • Play a neighborhood in obesity, insulin resistance, diabetes, and metabolic syndrome


So eating the proper amount of carbs for you is important. On keto, you eat less carbs and eat more fat. Just make sure to get your fat from smart sources like grass-fed animals, wild-caught fish, avocados, olive oil, and pastured egg yolks.

When you keep net carbs low enough — under about 30g/day for many variations of keto —your body may enter ketosis: a state where you shift from burning glucose or carb for energy, to burning fat for energy (including body fat). A keto diet may suppress your appetite, may decrease inflammation, and may assist you in losing weight.

On a keto diet, a keto cycling diet, or any other lower carb diet, people limit the carbs they eat to maximize fat-burning and minimize inflammation. That’s why it’s so important to understand the way to find out net carbs. Surpass your carb limit, and you’ll fall out of ketosis, and miss out on all the advantages.

How to Calculate Net Carbs for Keto (Including Sugar Alcohols)?

How to calculate net carbs basic formula to calculate net carbs is:

Net carbs for keto = Total carbs – fiber – sugar alcohols

EXAMPLE: 8g Carbs – 2g fiber – 2g sugar alcohol = 4g Total NET Carbs

The formula above is what you will use when calculating the net carbs on any label or dish you eat. 

However, not all sugar alcohols are truly carb-free, and a few manufacturers selling “low-carb” foods will list carb-significant sugar alcohols as if they’re exempt from total carb count, to form products appear lower-carb than they are.

On the opposite side of things, manufacturers will sometimes list sugar alcohols that don’t affect your blood glucose as if they were usual carbs, making net carb counts seem above they are.

The solution is to understand your sugar alcohols. The subsequent sugar alcohols don’t count toward net carbs for keto purposes:

  • Erythritol
  • Xylitol
  • Mannitol
  • Lactitol

If you’re eating something with the high sugar alcohols, you don’t get to include them in your carb count. These sugar alcohols below, however, do count (at least partially) toward net carbs:

  • Maltitol
  • Sorbitol
  • Isomalt
  • Glycerin

Each gram of maltitol, sorbitol, isomalt, or glycerin counts as about half a gram of carbs for keto, so take the number of grams of the sugar alcohol, divide by 2, and add it to your carb count. For example:

Net carbs = total carbs – fiber – sugar alcohols + (maltitol ÷ 2)

Use the above formula to calculate your net carbs for keto. And while we’re talking about sugar alcohols, it’s worth mentioning that while you can’t digest them, your gut bacteria sometimes ferment sugar alcohols to varying degrees, creating gas and bloating in your intestine. So don’t go crazy and eat too much of it. 

As a ballpark estimate, if you’re on a keto diet, don’t eat roughly 15 grams of sugar alcohols at a time, and be especially wary of mannitol, maltitol, and sorbitol — you’ll find yourself with digestive discomfort.

While it’s good to understand the way to calculate net carbs, you don’t need to track them too carefully unless you’re on a ketogenic diet. Barring that, the occasional extra few grams now and then won’t make a meaningful difference in your performance long-term. And if you discover you get dry eyes or unstable energy on a keto or low-carb diet, consider a weekly carb refeed day where you eat more carbs than usual. Most are slightly different; what matters is finding the carb intake that works best for you. Just make sure you follow the 75% Fat, 20% Protein, 5% carb rule!

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