A simple plan for someone new to paleo nutrition is to focus on eating 3 things (meat, fruit, vegetables) and drinking one (water). This means getting rid of all processed foods, all grains, all dairy, and all other beverages. This is an uncomplicated plan anyone can start with. Give it a month, see how you feel, learn more in the mean time, and tweak it from there as you see fit.

All of the answers above are great explanations of the Paleo diet. One thing I always keep in mind is we have no way to know exactly what paleolithic man ate. Many hunter-gatherers eat tubers, poi in Hawaii, for example. Another thing to keep in mind is what is healthy, like supplementing with vitamin d, which a caveman would not have done. The main reason I have seen people eating dairy is butter fat from grassfed cows is high in vitamin K2. Basically, if you can tolerate dairy, use raw milk dairy and don't over do it, with the exception of clarified butter which is a preferred cooking fat.

The easiest way to work it out is to divide between the paleo(lithic) and the neolithic (post-agriculture). This rules out:

• Grains
• Legumes
• Dairy
• Refined sugar

In paleo times certain things would also have been limited or seasonal:

• Fructose (from seasonal fruit)
• Nuts, seeds (seasonal)
• Carbohydrate in general (with the above categories ruled out, you're pretty much left with tubers like potato, which are rather work-intensive to acquire).
• Omega 6 in excess to omega 3 (no nuts, seeds, vegetable oil, or grain-fed animals)

Re. dairy, in a paleo context you wouldn't have access to specifically dairy proteins (casein and whey) or sugar (lactose). The fat in dairy is much the same as any other sort of animal fat, so foods which have had all (ghee), almost all (butter) or all but 1-2g per 100g (double cream) the protein and lactose removed are pretty safe. The issue is further complicated by the fact that different human populations and individuals have adapted to different degrees to dairy: hence why most Europeans are lactose tolerant and many Africans aren't.

There are two things to be said about potatoes. The first thing is that they're very carbohydratey. While some populations, like the Kitavans do find on heavily-carb based diets, generally HighFatLowCarb is seen as the paleo default and plausibly optimal (paleo or not). The second thing is the issue of specific plant chemicals in potatoes. Lots of people think that there are chemicals in foods of the nightshade family that are harmful, but it's best to deal with these details on a case by case and person-specific basis.

Just like any school of thought, there's bound to be disagreement within the camps. Kurt Harris has put together a great list, that most paleos recommend.

Based on his list and thoughts gleaned from Robb Wolf's podcasts, if you're trying to lean out, try this:

• ruminant meats and offal
• fish and other seafood
• non-starchy vegetables
• coconut cream
• raw, unpasteurized butter
• berries (limited)
• eggs

Then once you've reached your weight goal, add back in:

• raw heavy cream (if you can tolerate dairy)
• raw cheeses and other cheeses (like feta or gorgonzola)
• more berries
• more coconut products
• tubers

I like Kurt Harris' thought that it's about being healthful. It's not about reenacting paleo life. I also like Robb Wolf's thought that if you "look, feel and perform" better, then you're likely doing the right thing for you. By that thought, if you try the first list and you're not getting anywhere with how you look and feel, try moving eggs to the second list and see how you look and feel.

There are a lot of interpretations of the Paleo lifestyle/diet. You have to define your own. If you're just talking about the way of eating, basically it's fresh meat and fish, fresh vegetables, nuts, seeds and fruit that can be gathered and eaten with little processing.

Eggs and dairy are questionable, but many people still include them.

Root vegetables are questionable because most if not all have to be cooked to be edible. Another reason for some is the starch content.

If you just cut out packaged foods (and oils) and stick to fresh meat, fish, vegetables, fruit, nuts, seeds you're a few steps in the right direction.