How to Calculate Net Carbs
What are net carbs and why do they matter?
‘Net’ is what’s left over after you subtract something from the total. Whether cash or carbs, it’s the final amount that you can actually use.
But what do you subtract from total carbs to get net carbs? That’s where it gets tricky.
In this article, I’ll explain what constitutes a carb and show you how to calculate net carbs. Plus, you can try my simple net carb calculator.
What Are Net Carbs?
Carbohydrates are a macronutrient that comes from foods containing starches, sugars, and fibers. When you eat carbs, your stomach breaks them down into glucose (blood sugar) to be used for energy.
The problem is, some types of carbs don’t break down. These undigestable carbs come in the form of fiber and sugar alcohols.
Net carbs are what’s left over after you subtract the carbs you can’t digest.
Why Is Counting Net Carbs Important?
Low carb and ketogenic diets rely on the principle of lowering blood sugar to help you lose weight.
By reducing total carb intake, your body has less glucose to burn for energy. That means it has to use more body fat as fuel.
However, undigested carbs don’t raise blood sugar levels. So it’s only net carbs that need to be counted.
First off, there are two types of fiber called soluble and insoluble.
Insoluble fiber is not digested at all. Instead, it passes through your stomach and intestines intact. Therefore, it doesn’t contribute any calories.
Whereas soluble fiber dissolves and gets partially digested. Specifically, about 1/4 to 1/2 of the calories from soluble fiber get absorbed according to studies1,2.
While fiber may provide some calories, it doesn’t raise blood sugar. And that’s why fiber doesn’t count towards net carbs.
Another key aspect of net carbs is sugar alcohol. The food industry uses sugar alcohols to add sweetness with fewer calories than regular sugar.
The reason sugar alcohols have fewer calories is that our bodies can’t break them down properly. In fact, some types pass through you without being digested.
However, that doesn’t mean you can eat them to your heart’s content. Most sugar alcohols provide some calories. On average, about half as much as regular sugar.
Despite providing fewer calories, sugar alcohols can still raise blood sugar. Which is why half the amount of sugar alcohols count towards net carbs.
Here’s a list of the glycemic index and calorie content for common sugar alcohols compared to regular sugar:
The glycemic index quantifies how fast a carbohydrate breaks down into glucose. Where the higher the number, the more that food raises blood sugar.
With these numbers, you can see that sugar alcohol is slower digesting than regular sugar. And that means blood sugar stays lower.
At the end of the day, counting net carbs is a way to manage blood sugar levels and help you burn more fat.
How To Calculate Net Carbs
First, look at the nutrition label on your food package or look it up in an app like MyFitnessPal
Find the total carbohydrates, fiber, and sugar alcohols (in grams).
Subtract the grams of fiber and ½ the grams of sugar alcohol from the total carbohydrates:
Net carbs = total carbs – fiber – (sugar alcohol ÷ 2)
On the label below that’s 28 – 3 – (4 ÷ 2) = 23 grams net carbs.
Also, notice that sugar and sugar alcohols are separate. Because regular sugar is easily digested and spikes blood sugar – so it counts towards net carbs.
Net Carbs In Avocado
Of course, many unprocessed or whole foods don’t contain sugar alcohols. In that case, you just subtract fiber from total carbs.
As an example, let’s look at the net carbs in avocado. At first glance, it appears to be high in carbs. But then we see it also has a lot of fiber.
For a whole avocado, the math is 17 – 13 = 4 grams net carbs. Again, notice that we did not subtract the 1 gram of regular sugar.
As you can see, avocados are a good low carb food despite appearing high in carbs.
More importantly, understanding net carbs helps you make better food choices. When combined with exercise and energy balance, it’s a recipe for a healthy body.
Get Net Carbs Calculated For You
While the math is simple, it can still be a pain to track net carbs every day. That’s why I created a custom meal plan that calculates net carbs for you.
Each recipe in your plan automatically does the math. So all you have to do is prepare the meals and eat – no counting required!
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1) Oku, Tsuneyuki, and Sadako Nakamura. “Evaluation of the relative available energy of several dietary fiber preparations using breath hydrogen evolution in healthy humans.” Journal of nutritional science and vitaminology 60.4 (2014): 246-254.
2) Roberfroid, Marcel B. “Caloric value of inulin and oligofructose.” The Journal of nutrition 129.7 (1999): 1436S-1437S.