The truth about net carbs vs total carbs on a low-carb or keto diet
If you’ve started eating a low-carb or a ketogenic diet, you’re likely becoming familiarized with counting your carbohydrate (carb) intake. While the ketogenic diet is more focused on keeping carbs below a certain range, those following a low-carb diet will also need to limit their daily carb intake. It is common for many people to count net carbs on these diets rather than total carbs – but why is this? This article will go over the difference between the two, and which you might want to focus on if you’re eating a low-carb or keto diet.
Before we get started, lets discuss why we’re talking about counting carbs. When you switch to eating a low-carb or ketogenic diet, you will need to keep your macronutrients, aka ‘macros’ within a certain range. Macros are just a fancy word for the three nutrients the human body needs in the largest quantity. The three macronutrients are protein, fat and carbs. Coming from a standard diet you’re greatly reducing your carb intake, and unless you track, it can be easy to overeat carbohydrates in the beginning.
The Difference Between Net Carbs and Total Carbs
When reading a standard nutrition label, it is important to note the total carbohydrate count will include additional components that count towards the total carbohydrate number. In other words, the total carbohydrate number is referring to the carbs from all sources. Usually included on labels are sugar, fiber, and sometimes sugar alcohols. Taking the label below as an example, we can see the total carbohydrates equals 37 grams. You do not need to add fiber and total sugar to this, they are included in the total carbohydrate count.
When we talk about net carbs, we’re talking about everything included in that total carbohydrate number, minus the fiber. Put simply, net carbs = total carbs – fiber. Using the same label, we can see the total carbs are 37 grams, and the fiber is 4 grams. To get our net carb count we’re going to minus 4 from 37, giving us a net carb count of 33 grams. Note: the words dietary fiber and fiber are used interchangeably.
Which Carbohydrates Do You Focus on When Tracking Macros?
Fiber is the portion of carbohydrates found in plants that passes through your body partially or completely undigested. In other words, fiber is not absorbed by the body, and generally does not impact blood sugar like other carbohydrates. While we do know that insoluble fiber leaves the body completely undigested, the role of soluble fiber in the body is a little more complicated. Soluble fiber may be digested partially and doesn’t necessarily have zero impact on blood sugar.
On a nutrition label, sugar also falls under the category of carbohydrates. This number will include both added sugar and sugars found naturally in foods. So, a food with a number other than zero isn’t automatically banned from a low-carb or keto diet, it just depends on where the sugar is coming from. Avoiding all adding sugar is recommended, but natural sugars found in foods will not be. Even cauliflower has natural sugars! Make sure to read the ingredient list in addition to the nutrition information to avoid added sugars!
Sugar alcohols include xylitol, and erythritol. They are derived from plant sources, and generally speaking do not impact blood sugar levels. Like fiber, they pass through the digestive track undigested, and therefore do not need to be counted toward your total carb count. There are some sugar alcohols that have been shown to increase blood sugar - Maltitol and Sorbitol being two. If you see these listed, just know they may impact your blood sugar levels, although still not to the degree that real sugar would.
So, which should you count? When eating a low-carb high-fat diet, we generally want to avoid all added sugar as a rule of thumb. After that, sticking the net carb count will usually allow be an adequate measure of carbohydrates. Sticking to unprocessed, low-carb whole foods is always recommended.
Ultimately, it is up to the individual to determine his or her own carb tolerance. If you do plan to count carbs, there are some great tools like carb manager and my fitness pal that can help you get started. Those focused on eating low-carb high fat rather than strict keto will have more flexibility with the total carbohydrate number.
- Kohmoto et al.Metabolism of 13C-Isomaltooligosaccharides in Healthy Men. Bioscience, Biotechnology, and Biochemistry, 56:6, 937-940.
- Beaugerie et al.Clinical tolerance, intestinal absorption, and energy value of four sugar alcohols taken on an empty stomach. Gastroenterol Clin Biol. 1991;15(12):929-32.