The Paleo Diet is not strictly defined so there are a number of variations of the diet. It is easiest to describe the variations of the Paleo Diets by the people who have created or promoted them.
One of the most popular variations is the one Loren Cordain described in his book The Paleo Diet (the latest version of his book is named The Paleo Diet Revised). Cordain has written a number of books about the Paleo diet, including cookbooks with recipes. He recommends a relatively strict Paleo diet. The diet is based on lean meats, fish & seafood, fruits, vegetables, nuts, and seeds. The meat should be “grass-produced” and trimmed of visible fat. The list of what not to eat contains dairy products, potatoes, processed foods, salt and cereal grains. But you are allowed to consume three non-paleo meals per week, allowing you for example to drink small amounts of alcohol. You can read more about Dr. Cordain’s recommendations here.
Robb Wolf is another author of a popular Paleo Diet book, The Paleo Solution. He is a former student of Loren Cordain and recommends much the same kind of diet as he. But there are a couple of differences. Wolf is less worried about red meat than most others, as long as the meat comes from pasture raised animals, it is not a problem, regardless of the saturated fat. Robb Wolf does not recommend alcohol but has recognized that many people like to drink alcohol once in a while so he has created his own version of the Margarita drink, the NorCal Margarita. Beer should not be drunk, wine is a better choice.
Mark Sisson is a well known name in the world of Paleo Diets. He has written several books, the best known is “The Primal BluePrint.” It is not just about diet, it covers most aspects of an active and healthy lifestyle. His diet suggestions are similar to those of mainstream paleo diets. One interesting point is that he recommends supplementing your diet with pure fish oil capsules, in order to get enough omega-3 fatty acids. The main natural source, cold water fish, is often contaminated with mercury and pesticide residues. He is also promoting meat, and the fat it contains, which can make your metabolism animal fat-based. If you want to lose weight, you should cut down on carbs and eat more fat, in case of meat.
Ray Audette’s NeanderThin was one of the first successful paleo diet books. It is out of print but available as a Kindle book. The author summarized his advice with: “Never eat anything that you cannot get naked, armed with only a sharp stick.” His advice was simple, no processed food. If you adopt such a diet, a high-calorie, high-fat diet can actually make you leaner. Over the years, a lot of diet experts, most of them “non-paleo”, have criticized his diet which does not limit fat consumption. Of course, he is not the only one who has been criticized, almost all diets which don’t put any limits on fat have come under fire.