Here is a simple how-to guide from the great Owsley "The Bear" Stanley, a zero-carb eater for over 50 years. This guide was originally published on Zeroing In On Health. After a comment about organ meat, I wanted to share The Bear's opinions on the matter, and this is a concise way to do so:
SEVEN SIMPLE RULES FOR THE HUMAN CARNIVORE
1) Eat only from the animal world (eggs, fish, redmeat and fowl and some dairy are all animal sourced foods, i.e.: meat).
2) Eat nothing from the vegetable world whatsoever. (Very small amounts of flavourings such as garlic/chillies/spices/herbs which may be added, are not ‘food’).
3) On diary: avoid milk and yoghurt (heavy carbs- lactose), use only pure (not ‘thickened’- heavy) cream (read the label), cheese and unsalted butter.
4) Don’t cook your meat very much- just a little bit on the outside- for flavour- blood-rare or bleu. For this reason I advise against eating pork.
5) Eat liver and brains only very infrequently- they are full of carbs.
6) Be sure to have plenty of fat of animal origin at each meal and eat mostly of the fat until you feel you have had enough- you can eat more lean at this point if you like- calories are not important, nor is the number of meals/day. Vegetable oils are not good food.
7) You do not need any supplements of any kind. Drink a lot of water and do not add salt to anything.
That is all there is to it.
DO NOT obsess over what you eat, follow the rules and it will become second nature, and you will not have to think about it at all. What you eat is a social conditioning, most people will never alter their diet from what their mum fed them as babies, only those rare individuals who have a strong will and desire for a normal-sized, healthy body can do it. Even the grossly obese have trouble with my path. You may feel low on energy for a few days or weeks, but as soon as you keto-adapt to zero-carbs that will pass and your energy will be increased.
GGP - So while I'm 'obsessing' in order to track this experiment, I actually feel much more freedom, since I can eat when I want, until I'm satisfied, without having to think about carbs or calories. Calories aren't calculated until I log my food in the evening, and is sometimes higher that I would let it run if I were truly obsessing. And the inverse - some huge meals end up being far lower in calories than my sated sensation would suggest! :)