I bet you’ve wondered if you should be counting total carbs or net carbs at least once in your keto journey? Am I right? Let’s settle the debate once and for all!
Disclaimer- if you are a diabetic, count carbs for your insulin and diabetic needs first as negotiated in your diabetic support plan.
I’ve always been a supporter of net carb counting for keto, until recently that is. I’m more of a supporter of both, but in different ways. Basically, it works out to what I call a flex approach to counting carbs. We’ll get into what this is in a bit, but first, let’s go into a little background on total and net carbs.
What Are Total Carbs?
If you look at a nutritional label, the total carbs are what is listed next to the carbohydrate heading. This tells you the total amount of carbohydrates (in grams) for a particular serving. This includes sugar, starch, fiber and sugar alcohols. And always be mindful that this is per serving, not necessarily the entire food item. Remember – they like to get sneaky with their labels!
What Are Net Carbs?
Net carbs are what is left over when you take total carbs and subtract off fiber and sugar alcohols. This leaves you with the digestible carbs that are used for energy, more or less. Fiber and Sugar Alcohols are undigestible and therefore are not included in the net carb count. Or at least that is what we are told. This has become more of a food industry game than actual science. We’ll get to the truth behind this in a bit.
How To Calculate Net Carbs
Real simply : <Net Carbs> = <Total Carbs> – <Fiber> – <Sugar Alcohols>
Why Are Net Carbs Misleading?
We are told that neither fiber nor sugar alcohols will affect blood sugars. And as a diabetic, I can tell you that this is not the case.
Case in point. My Type 1 Diabetic friend Sara did an experiment. Let me preface this by saying she follows Dr. Bernstein, low carb eating and has meticulous control over her blood sugars.
Sara bought a package of either 0 or 1 NET CARB keto bun and ate one. Her blood sugar was 93 and she did not take insulin for the bun. Just over an hour later, her blood sugar had risen 50 pounds to about 140. Because of her tight control, she is well aware that her correction factor is 1g of carbs to raise her blood sugar 5 points. This information told her that this bun had at least 10g of carbs or at least that is how her body responded to it. While this is oversimplifying it a bit, you get the idea.
I went out and found the buns to take a screenshot of the ingredients list. These are the Franz buns that I’m sure most of you have seen. Let’s take a moment to go through the ingredients of these “keto” buns:
Wheat starch, wheat gluten, inulin, oat fiber, wheat protein isolate, water, yeast, soybean oil, and then a bunch of other crap.
The first ingredient is wheat starch. Wheat starch.
What is Wheat Starch?
Wheat starch is from the endosperm of the wheat grain. Basically, the wheat grain is crushed, processed, stripped and BOOM, pure starch remains.
This also means it is gluten free, by the way, and this ingredient is often used in gluten free baking.
Does Wheat Starch Contain Carbs?
Why, yes, it does. According to Nutritionix, 10g (1 tablespoon) contains 7.6g of carbs and .3g of fiber.
So I will admit that I don’t understand how wheat starch can be the main ingredient with a net carb effect of only 1. Unless some fancy footwork is being done with the added fiber.
Does Fiber Raise Your Blood Sugar
This is an interesting question. The general answer would be no. But that is not entirely accurate. There is a difference between naturally occurring fiber and ADDED fiber and in fact it has been proposed that food labels list naturally occurring fiber and isolated/added fibers separately. But as it stands right now, this is not the case.
Added fibers are commonly found in the form of psyllium, soy, cellulose, inulin, guar, oat beta-glucan, polydextrose, fructooligosaccharides, and digestion-resistant maltodextrin .
Diabetics are told to subtract off ½ the fiber if it is over 5 grams. This right here tells you that fiber, in some capacity, has an effect on blood sugar. After all, fiber still has calories – about 2 calories per gram which is ½ the amount of sugar.
Types of Fiber
There is also soluble and insoluble fiber. Soluble means it dissolves in water and insoluble does not. Soluble fiber is ingested by the bacteria in our digestive track and produce a short chain fatty acid that our body can use for energy . This will obviously vary quite a bit person to person since all our bacteria content are vastly different. But even if we ignore the differences in bacteria in our bodies, studies have shown different fibers to have a vastly different positive or negative energy contribution. The conclusion is said perfectly with this quote from an awesome study on fiber
Two clear conclusions can be drawn from this overview. One is that fibers may clearly contribute to energy balance in an affluent society because of its very low and sometimes even negative energy value and because of satiety-inducing effects (Figure 1). The energetic value is related mainly to fermentability and antinutritive effects, where viscous soluble fibers may have a considerable net negative energy value due to attenuating effects on macronutrient digestion and absorption, whereas soluble nonviscous fibers will contribute moderately to energy through fermentation.Hervik AK, Svihus B. The Role of Fiber in Energy Balance. J Nutr Metab. 2019;2019:4983657. doi:10.1155/2019/4983657 (https://pubmed.ncbi.nlm.nih.gov/30805214/)
So, what does all this mean? It means that subtracting off ALL fiber can be misleading and potentially produce negative effects on blood sugar(i.e. higher blood sugar) and positive energy (i.e. calorie) contribution.
What Are Sugar Alcohols?
Sugar alcohols, oddly enough, are neither sugar nor alcohol. Instead, when you look at the chemical structure of a sugar alcohol, it partially resembles that of alcohol and partially resembles that of sugar. Sugar itself is 4 Calories per gram and sugar alcohols range from .02 to 3.
Common Sugar Alcohols
Below are the most common sugar alcohols and their respective calories :
Erythritol contains .2 calories per gram and has a 60-80% sweetness.
Sorbitol contains 2.6 calories per gram and has a 50-70% sweetness.
Xylitol contains 2.4 calories per gram and has 100% sweetness.
Maltitol contains 2.1 calories per gram and has 75% sweetness.
Isomalt contains 2 calories per gram and has 45-65% sweetness
There are more but these are the most common.
On a side note, my preferred sweetener is stevia. It is not a sugar alcohol though. It is 100-300x as sweet as sugar and has no calories. Oh, and it is from a plant and naturally occurring in nature. Win/Win.
How to Count Sugar Alcohols
As you can see, sugar alcohols are not free. Keto followers are often told to subtract off the sugar alcohols, but this is a bit misleading. Diabetics are often told to subtract ½ of the sugar alcohols which is a bit better. I can stand behind subtracting off half since many of them come in around 2 calories per gram whereas sugar comes in at 4 calories per gram. So, it is about half, just as with fiber.
But the keto advice is to subtract off the entire amount. Absolutely not.
From personal experience I can tell you that sugar alcohols do affect my body. Some affect my blood sugar. Some do not. Years ago when I first started keto, I lost 20 pounds and was strict keto (no sugar alcohols, no desserts, etc..). I started blogging and creating desserts because I realized that so many people cheat or leave keto because they can’t have an occasional treat. So, I wanted to solve that problem in order help make keto a lifestyle. A sustainable lifestyle.
Here is what happened though….. I started baking all these desserts for my blog and then, of course, eating them by myself basically. Sometimes I would have keto pie for breakfast, you get the idea. My weight loss stopped. My calorie consumption probably went up a small amount, but not that much because I wasn’t stuffing myself, I was just skipping meals and taste testing my desserts instead.
There were a lot of factors at play, but one was all the sugar alcohols that I was “subtracting off”. They actually were having more of an effect than I had originally thought. Just a little real world experience for you there.
Flex Carb Counting
At the end of the day, it all depends on what your goals are in terms of keto. I was always a net carb snob because I didn’t want people shying away from eating an avocado which is 12 total carbs, but only 2 net carbs and other healthy foods like that.
But as we’ve discussed, not all fiber is equal, just like not all sugar alcohols are equal. Now, I lean more towards a flex approach.
I have to say that I am a bit lucky that I wear a CGM so that I can see what my blood sugar does at all times. I can learn which foods raise my blood sugars and which ones don’t. This is what matters at the end of the day because a rise in blood sugar means that fiber and sugar alcohols were not benign after all. This matter for everything from ketosis to weight loss to blood sugar control. It is not just a diabetic thing. Take a peek at How to Reverse Insulin Resistance and Keto Diet and Insulin and see why it matters!
I used to count the carbs twice basically. I would count them one way for my keto calculation (i.e. subtract off all fiber and sugar alcohols) and then I would count them another way to give my insulin (i.e. subtract off ½ the sugar alcohols and ½ the fiber if over 5g).
But here is what I do NOW. I start with my diabetic approach and extend that to my keto calculation as well. But in doing so, I raised my “net carb” limit from 20 to 30. Some raise it to 50, but that is usually when they don’t subtract anything. I felt if I did that, though, then I would be slightly defeating my goals so I took a middle of the road approach.
Here is the personal experiment that I did that really solidified my decision. I spent 4 days doing the experiment. I used the traditional keto way of counting net carbs and subtracted off all fiber and sugar alcohols. Going into this experiment, my blood ketones were between 3 and 4 and my blood sugars were generally in the 90s, not going above 100. The first 2 days, I ate real foods. Nothing processed, just meats, vegetables, healthy fats, etc.. My blood sugars and ketone levels remained steady.
The 2 days following, I replaced some of my foods with keto bars which each had a total carb count of 12 carbs and 9 grams of fiber. I love these bars, by the way. My FAVORITE!!! But, basically, those are the same macros as an avocado so I replaced an avocado with a bar and then replaced a homemade smoothie with a bar.
I kept my calories and macros reasonably similar. But on the 2 days that I was eating processed foods, my blood sugars rose above 100 several times and my blood ketones dropped to around 1.8. That spoke volumes to me as far as not all carbs are created equal. And real food fiber that doesn’t come in a package seems to have less of an impact. Now, certainly I can’t make a blanket statement like that with just one experiment. I’ve done several. But, yes, take the statement with a grain of salt and do your own experiments.
Truly, though, do what works for you. But before you eat a bunch of processed high fiber foods or high sugar alcohols desserts thinking that none of these will have an effect on your goals, I want you to think twice. Natural whole foods should be first and foremost. Natural fiber. Whole foods. Carb counting becomes much easier when you aren’t adding fiber and adding sugar alcohols just so people have to subtract them off so that it appears low carb but in reality has a high impact on blood sugar and can sabotage even the best laid out plan.
 Hervik AK, Svihus B. The Role of Fiber in Energy Balance. J Nutr Metab. 2019;2019:4983657. doi:10.1155/2019/4983657 (https://pubmed.ncbi.nlm.nih.gov/30805214/)