"Total" or "Net" Carbs
Which should we use on a Keto Diet?
What are “carbohydrates”?
Carbohydrates, protein, and fat are the three energy-producing macronutrients. Most foods, except for a few mineral salts, include one or a mixture of these macronutrients. Through the process of metabolism these nutrients are converted to energy that can be used by the various cells in the body to fuel that cell’s function.
Proponents of low-carb diets such as Atkins, Paleo and the more generic Keto Diet propose that consuming too many dietary carbohydrates causes a chronic increase in concentrations of both insulin and glucose in the bloodstream. This, in turn, can be a cause of weight-gain and can be a contributing factor for many metabolic diseases, including diabetes and heart disease.
These various diet plans are based on the consumption of food containing fewer carbohydrates, and conversely, more protein and fat.
High-carbohydrate foods, compared to foods high in protein and fat, generally cause more significant spikes in blood sugar. [ González-Rodríguez 2019 ] In fact, only 20g of glucose (carbohydrate) causes a significantly higher glucose spike than even 100g of protein during the first three hours after ingestion. [ Paterson 2016 – Australia ] Foods high in dietary fat, such as butter or olive oil, consumed alone, have little or no immediate impact on blood glucose.
How should fiber be treated on a Keto Diet?
Not all carbohydrates have the same impact on blood sugar and insulin. Complex carbohydrates, like starch, in potatoes, have less impact than simple carbohydrates, like table sugar. Fiber, another form of carbohydrate, is non-digestible in humans, and accordingly, foods high in fiber have nominal impact on blood glucose provided they are not otherwise high in digestible carbs. [ Hervik 2019 ] [ Thompson 2017 – USA ]
In fact, research indicates that high-fiber foods actually have the effect of lowering the glycemic impact of a meal in non-diabetics and both type 1 and type 2 diabetics [ Thompson 2017– USA (Review of 12 controlled trials)] [ Basu 2019 – USA (Epi CACTI Cohort)] [ Potter 1981 ] [ Silva 2013 – Systematic Review of 11 Randomized Controlled Trials ].
We explain the pros and cons of fiber based on the latest research and why for most people the optimal Keto Diet should include soluble fiber in our article on “Fiber on the Keto Diet”.
The definition of “Net Carbs”
The Atkins Diet website defines “net carbs” as the total carbohydrates less fiber and sugar alcohols. This carb-counting formula has been the used for computing permissible carbohydrate intake on low-carb diets for five decades.
Sugar alcohols (something quite different than common sugar) are another type of carbohydrate that is at least partially non-digestible, depending on the particular type. The two that have the least impact on blood glucose are erythritol and xylitol. Erythritol is the clear winner having virtually no effect on blood glucose. We note that artificial sweeteners such as stevia and sucralose have no carbohydrate content and also do not affect blood glucose concentration adversely either.
Check out our article about sugar-substitutes on a Keto Diet.
Should I use “total carbs” or “net carbs” to determine which foods I should be eating on a low-carb or keto diet?
The established practice for decades of using “net carbs” to compute permissible levels of dietary carbohydrate intake isn’t accepted by everyone in the low-carb community. Some low-carb and ketogenic diet proponents state that using “net carbs” creates a problem when seeking guidance on which foods are acceptably low-carb since sugar-alcohols are not broken out as line items on the government-required Nutrition Facts label for packaged foods that using “net carbs” can cause confusion.
Any validity to the sugar-alcohol labeling argument is, in our estimation, a moot argument since it’s only valid for processed foods with labels which everyone agrees should not be included in a healthy Keto Diet.
Others state that fiber should not be deducted from the carbohydrates being avoided based on the allegation that it causes an adverse insulin and blood glucose response that could interfere with maintaining dietary ketosis. This is, as we previously indicated, contrary to all the scientific evidence. [ Thompson 2017 – USA (Review of 12 controlled trials)]
Not deducting the fiber when counting carbs discourages including high-fiber cruciferous vegetables from a low-carb and ketogenic diet. This is both contrary to the objective of lowering blood glucose and makes including many essential vitamins and minerals without supplementation almost impossible. There is also a growing body of evidence that fiber is essential for maintaining homeostasis in the gut microbiome and that this balance of types of bacteria is intimately connected to both weight-gain and disease pathology. Researchers in England examined DNA from 1,632 women and concluded that “high gut microbiome diversity (and) high-fibre intake are … correlated with lower term weight gain in humans independently of calorie intake and other confounders.” [ Menni 2017 – UK ]
Perhaps the most important reason for including fiber in your diet is that the diversity of the food when using a “net carbs” approach makes adherence to the diet far easier without sacrificing any of the positive benefits of the diet.
There is no valid metabolic argument nor anything other than anecdotal clinical experience of YouTube low-carb proponents to support using “total carbs” versus “net carbs”. I’ve personally repeatedly tested the effect of foods that are high in soluble fiber on my blood glucose. They, as the science indicates, actually result in a postprandial drop in blood glucose. Check out the details of those anecdotal experiments in our article “Fiber and Net Carbs: The proof is in the Avocado Pudding”.
In closing, we note that some Keto Diet proponents admonish dieters not to count carbs at all. Oddly, one recently stated that beans were acceptable on a ketogenic diet despite being extremely high in both total and net carbs. We’ve made counting “net carbs” easy with our Carbs Calculator which shows the “net carbs” for each food item you add to the daily meal plan and also shows the cumulative total of the most important nutrients as you add more items to the list. With our Carb Counter it’s never been easier to see the ‘’net carb” impact of more than 350 whole foods. The Keto Diet just got easy!
