I agree, taking extra fiber supplements can be bad, or overwhelm the gut. But you can eat vegetables, and get fiber, but at a lower volume of fiber before you get constipated.
I'm just on side that vegetables are important. And the carnivore diet people don't seem to get enough vegetables generally, and all the other nutrients in vegetables. Even thought, you can do Keto with low carb vegetables. It can be done. Thought difficult.
Also. Gluten. When I cut out Gluten, that also cut out a ton of carbs (no breads). If you just eat vegetables without grains, it is pretty low carb.
Maybe, by the time you eat just meat, or just whole plants, or even a combination of whole foods (meat and vegetables, minus grain), your are being much more healthy in general than the Standard American Diet.
really, just eating a whole baked potato can be considered low carb compared to someone downing oreo's.
After sorting that out I added some psyllium fibre tablets and I'm mostly sorted.
When I finally tried the low residue approach of carnivore it relieved my symptoms by the next morning. As a result I've become skeptical that either fiber or carbs are health foods for me. I'm also much more skeptical of the epistemic capacity of nutrition research.