Why do carnivorous cannot digest carbohydrates.
Answers
Answer:
Carnivores digest carbohydrates just fine!
Their prey have muscles containing stored glycogen, a starch.
Their prey have livers containing stored glycogen as well.
Half of the amino acids from digested protein are converted into glucose on first pass through the liver before they could enter general circulation.
Carnivores get quite enough carbohydrate. There are two problems, however.
Many of the carbohydrate sources that one might try to feed to a carnivore contain toxins that a herbivore could deactivate but a carnivore lacks the liver enzymes to do that. For instance, onions, garlic and related root plants cause hemolysis in cats. Many vegetables and some fruits contain salicylates which inhibit blood clotting.
Carnivores cannot handle large amounts of carbohydrate. For that matter, neither can humans. After enough years on a sugar and starch diet a human develops insulin resistance, metabolic syndrome, atherosclerosis, type II diabetes and eventual kidney failure. The same happens to cats because the typical convenient dry kibble that people feed to cats is held together with starch and a lot of that.
Wet cat food contains less starch. Even kibble can be improved by cutting the starch to just what is required to steam-extrude the product. Then add as much animal fat that the kibble will hold without having it migrate out of the bag. The old Science diet was like that. We called it “designer grease balls” and the cats just inhaled it. More recent versions are less greasy and in my opinion are not as good.
I mention cats because dogs do not have the same problem. Unlike wolves, millennia of eating human leftovers forced them to accumulate enough random mutations to become omnivores. Foxes, coyote and other small canids were never obligate carnivores. They had to eat whatever was available including fruit and roots