It depends on both the carnivore and the prey. Many predators eat prey much smaller than they are and eat the entire prey in just a bite or two. Owls swallow mice and other rodents whole, for instance. read more
Animals like lions, wolves, and bears, do, indeed, eat all of the animal that they are able to; starting with the parts the predator deems most tasty or valuable. Lions, for instance, often tear open large prey right away to get at and eat the internal organs before they start eating the muscles (meat) of the animal. read more
Human and carnivore digestive systems are designed for and equipped to eat meat. Both humans and carnivores eat and break down animal proteins, lipids and vitamins directly from animal sources. (Herbivores by definition do not eat animals, but they still need 'animal protein,' and they obtain it from the many pounds of bacteria which they continually digest.) Human digestion does not break down plant materials efficiently. read more