Neither fiber or lactose are needed in the adult human diet.
Discussion
My main goals with carnivore are to reduce chronic inflammation. I can say for sure that the number one thing the improves that is to just not drink alcohol. After that, don’t eat processed food or grains. Also, intermittent fasting seems to be pretty helpful.
there is many irritants that fibre mitigates, though
but i have generally found that i can't absorb more than about 30g of fat in a meal unless it's also got about 30g of fibre along with it, and when i say fat, i mean tallow, butter, lard
my intuition is that fibre mitigates irritation, but it is not essential, what is more effective is removing the irritation
that can be a real minefield in a modern supermarket, all the ones in europe i find there's almost nothing that isn't poisoned