For an example, my own version of keto/carnivore, as written up for my new doctor, who has been on keto for 7 years! (I haven't had my official appointment yet, so I wrote up a one page summary.)
<20 carbs/90% animal products
Elimination of all reactive foods: sugar, grains, lectins, nightshades, soy, most seed oils
Unlimited: beef, pork, dark meat poultry, salmon, shrimp, tuna, eggs
Daily and/or small amounts: fermented high fat dairy, dill pickles, berries, cherries, onions, dark chocolate, guacamole
Oils: coconut, hemp, olive
Controlled for fiber content: greens, cabbage, carrots, celery, coconut
We did meet for DH's consult, and this doctor loves bulletproof coffee
So do I.