Are Net Carbs a marketing scam?

Published 1.27.2025: So the concept of “net carbs” is where you subtract the carbs due to fiber from the total number of carbohydrates in a food. I think this became a thing in the low carb dieting world, and frankly I never counted carbs (or any macro, which to me is just another way to count calories). But because of the trend “fiber maxing”, perhaps, (I have no link to share on that one) the concept has been brought up again.

To me, counting net carbs rather than carbs is just an excuse to eat more carbs. But I will admit, that I actually believed that carbs from fiber did not result in calories. Fiber passes though the small intestines into the colon, without being absorbed.

In the colon, fiber is processed by the microbiome there, and then become fecal matter. People who eat a lot of plants tend to have larger, looser stools than those who don’t. So far, nothing I’ve written is controversial, or unknown. Some people have issues with increasing fiber in the short term, there are plenty of influencers who think fiber is bad for you. I think these people are cuckoo, but you do you.

The issue for me, which I heard about on a podcast (Chasing Clarity), is that fiber still has calories for the body. I knew that the microbiome in the colon dealt with fiber, but for some reason I never thought that they would produce things for the body that would have calories.

This is not science article, but it says that fiber can add up to 2 kilocalories per gram. I knew before that there were (primarily) two types of fiber, soluble and insoluble. Insoluble fiber tens to pass right through you, whereas soluble fiber tends to get fermented by the bacteria and produce short chain fatty acids, which do have calories.

The article goes on to say that it’s very difficult to measure calories produced from fermenting fiber (read that as soluble fiber, because most insoluble fiber doesn’t ferment.) Different countries handle it differently in terms of nutrition facts— which just makes calorie counting less accurate. But only at the extremes (such as a keto diet) does the calories from fiber become an issue.

This is a science article, by a doctor (Dr, Bulsiewicz or Dr B) I’ve heard on numerous podcasts touting the benefit of fiber. Interestingly, because he’s a doctor, he is not on board with the fiber maxing trend. He’s a gastrenterologist, and he’s all about motility. He notes that if you’re “bunged up” as Zoe Harcombe would say (wow, that’s a deep pull), too much fiber will not be helpful. Fiber is important to ingest, but not if your body can’t handle it. You need to work up slowly in terms of fiber, rather than “maxing” out the total.

Both articles cited tout the benefits of fiber, but why is the concept of net carbs a marketing scam? Because the sense is that if you eat fiber, they won’t count. It’s like a cheat code for dieters (though everyone who eats is a “dieter”). At least that was how I understood it.

I no longer track anything (including calories) but when I did I never bothered with net calories, and maybe it’s a good thing I didn’t. Basically, everythign that went into my mouth got counted— macronutrient amounts be damned.

In his science article, the doctor makes the point fiber is important for metabolic health, and that inceased fiber ingestion would help a bunch of diseases, most of the ones that kill Americans the most. Plainly, eating more fiber as part of your diet is a good thing. Just don’t try and count the fiber against your carbs, because 1) fiber results in calories and 2) it’s hard to count those.

Don’t believe the hype. The concept of net carbs is bunk, but plants are a good thing to ingest. Don’t believe keto cult leaders (or the current leader of the Health and Human Services for that matter.

The article written by the doctor above is not research, indeed it’s a trek through the research on fiber. I don’t think it qualifies as a review, but he does state the results from various meta-analyses (which are supposedly the highest form of research). Don’t know about that because a lot of meta-analyses don’t include a lot of studies, or the studies inlcuded don’t use the same methods. Overall, my opinion of meta-analyses has suffered in recent years.

That said, it’s hard to read the variety of research on fiber that’s been done and conclude that it isn’t helpful. Unless, again, you’re part of a cult that thinks vegetables are trying to kill you. In which case, I can’t help you, and neither can the good doctor.

Please note that nothing in this article suggests that you need to become vegan (eschewing all animal products). A healthy pattern of eating can be established as ominivorous. Getting adequate fiber in a way of eating (diet) does not depend on limiting oneself to plants.