Pemmican is a condensed carnivore food that was popular in the past to trappers and hunters, as well as the Native Americans that made it from bison. One bison could be rendered and chopped and dried down into a 90 pound clump stored in its hide - made of rendered fat mixed with lean dried meat that is pounded into a powder. Pemmican represents the perfect fat:protein ratio and keeps for a long time as the stable saturated fat protects the dried out meat, which, devoid of moisture, cannot rot. It could be left in a cache for years at a time and still be eaten. Wars have been fought over it.
Trapping, Exploring, Hunting
The sales of furs, and the exploration of new routes to new lands, and finally the hunting of animals made a significant impact in the history of the modern world, and often the people living remote to civilization would have to take advantage of the ways of the native people and eat like them. In this way, they would be carnivores by need, as fishing, hunting, and eating trapped animals would be the best way to get a meal, and animals can be processed down into high fat pemmican to get the best bang for the buck when it comes to transporting fuel as weight.
Facultative Carnivore describes the concept of animals that are technically omnivores but who thrive off of all meat diets. Humans may just be facultative carnivores - who need no plant products for long-term nutrition.
The carnivore diet involves eating only animal products such as meat, fish, dairy, eggs, marrow, meat broths, organs. There are little to no plants in the diet.