A paleo diet is one based on the premise that the optimal diet is that of our evolutionary ancestors during the paleolithic era. Since many diets fit this heuristic, many variants have been developed and popularised under names such as caveman diet, paleolithic diet, and primal diet. It is a fad diet. It is typically based on eating only those foods which a hunter-gatherer society would have eaten, such as meat, nuts, berries, fish, vegetables, fruits, and tubers. Excluded are foods that are the products of large-scale agriculture such as grains, bread, dairy products (in some versions), legumes (beans, peas, etc.), and processed sugar and salt.
The "paleo diet", like most diets, has evolved over time and has many variants. Its earliest phase is associated with Loren Cordain and is based around only paleo food-types, as above. It is the diet in this guise that has attracted most research in terms of diet trials. Conversely, popular forms of the diet, for example, those advocated by paleo bloggers, commonly diverge from this. Recently there has been a significant movement towards "Paleo 2.0" which rejects simply eating the foodstuffs of the paleolithic, in favor of eating whatever foods best reproduce the "evolutionary metabolic milieu". A simple example is that while Paleo 1.0 would reject cream as a novel foodstuff, Paleo 2.0 would tend to embrace it as a close analog of animal fat. Paleo 2.0 is also more likely to embrace biochemical and dietary research that is extraneous to pure paleo reasoning: as such Paleo 2.0 is more accepting of both extreme low carb and high fat diets, high starch diets, traditionally prepared grains, inclusion of dairy, etc.
In its original form, the paleo diet was a combination of two popular fad diets: the low-carb diet and the gluten-free diet. More recently, however, many paleo proponents are moving away from low-carb, citing such modern hunter/gatherer societies as the Kitavans, who survive largely on tubers and are in impeccable health.
Paleo diet fans call the foods they avoid "neolithic" foods as they did not come into widespread human consumption until the agricultural revolution, despite ample evidence that man has been cooking wild potatoes, corn, legumes, and a variety of sugars for at least 400,000 years. A problem with refuting or supporting a diet based on prehistoric man is that details are, well, prehistoric. The history of cooking is, like most studies of ancient humans, highly controversial. The earliest dates suggested by scholars are 2 million years ago. A very small minority suggest that cooking began just 40,000 to 10,000 years ago with the advent of agriculture. Most scholars accept some middle ground of 400,000 - 200,000 years ago.
It should be mentioned that much of the Paleo diet movement is focused not on the work of anthropologists but on that of Weston Price regarding the effects of then modern (1920s-1930s) processed food on so-called primitive cultures which were seen as "living fossils" of neolithic man.
 What do paleo dieters eat?
As with any fad diet, the paleo diet comes in many flavors and many ranges of extremity. In general, though, the following tenets should hold true:
- Meat, especially birds, wild caught fish and grass fed ruminants. Variation exists among paleo belief as to how fatty paleolithic meats would have been.
- The offal of the animals listed above.
- Large amounts of vegetables.
- Fruits (limited by some).
- Tubers, such as sweet potatoes and sometimes white potatoes (limited by some).
- Butter, lard, tallow, coconut oil, and other fats and oils not made from grains or seeds.
- Fermented foods such as sauerkraut, kombucha, and kefir.
- No added sugar, especially high-fructose corn syrup.
- No grains or legumes, though some argue that soaking and/or fermenting them makes them acceptable.
- Dairy is often excluded or limited, but high fat or fermented dairy is often included by so-called 'lacto-paleos'.
As with any woo, adherents vary in how extremely they take it, from just cutting out processed foods, to fully cutting out all grains and dairy, to those who only eat things they can gather themselves, either directly, though hunting, gardening, etc., or indirectly, through local hunters and farmers or online stores. For some purists, even things like tomatoes are off limits despite being something that can be "gathered", because they were not known to be consumed by paleolithic man. Eggs are allowed because they are theoretically something that can be gathered in the wild. Alcoholic beverages tend to be avoided because beer and most liquor are produced from grain and require processing, but wine and mead could in theory be "found" in naturally fermented foodstuffs. Honey and stevia are some of the most commonly allowed sweeteners, though some also include maple syrup. However, a critic might delight in reminding any paleo dieter that you must boil sap to get syrup, and the technology to have something to boil in is pretty "new" in human history. In practice, this diet is most often high in animal products and vegetables, though vegetable-intensive versions with meat limited to wild game are followed. There are also raw foodist variations. A paleo-style diet is generally time-consuming to "gather" (even if it's just at the local supermarket) and prepare, just as any other diet that cuts out processed foods.
 What did paleolithic humans actually eat?
Paleolithic diets necessarily included things that most Americans (who are the primary consumers of this woo) wouldn't touch with a 10-foot squeamish pole. Next time you meet a paleo, ask him or her if they eat:
- Small game — really small game — like rats, mice and squirrels.
- Unpleasant plants, pre-selective breeding. Sour and bitter tastes existed in many plant foods before human interference. Although paleolithic man probably would avoid downright foul-tasting (and likely poisonous) food, the plants that they ate were hardly nice, friendly spinach or carrots. Many modern vegetables are more pleasant mutations and hybridizations of less pleasant or even poisonous plants such as the genuses solanum (tomatoes, potatoes, peppers) and prunus (almonds, peaches, apricots, plums, cherries). Safe varieties were likely discovered by just eating them and hoping it didn't kill anybody. In addition, paleolithic people are known to have eaten woody stems, stripped bark, and pith: things suspiciously absent from the modern paleo diet that probably contributed to the extreme wear and tear on their teeth observed in fossil individuals.
- Organ meat — a critical part of paleolithic man's diet. Does the average paleo dieter eat brains, tongues, stomach, eyes, liver, or kidneys? All of these brought important nutrition to our "healthy" ancestors that doesn't exist in white meat and cuts of grazing beef.
- Insects, especially grubs and large beetles, including roaches.
- Lizards, newts, frogs, turtles and anything else that had meat on its bones.
- Grains and other starches such as sorghum, wild corn (in both North and South American), potatoes (South America), and a large variety of seeds. Evidence for consumption of legumes such as wild lentils has also been found, along with stone tools associated with processing them.
- Fruits and nuts.
 How high-protein diets can work
The paleo diet, with its emphasis on meat consumption, is naturally amenable to a high protein intake. High protein diets, such as the South Beach Diet and Atkins, are popular for weight loss and have attracted a large amount of research.
Some reasons suggested for why high protein diets work include:
- When eating protein, the brain sends a hormone that tells the stomach to stop eating. Studies show that people who include a significant portion of their meal as protein (30-50%), will not desire food, especially "snacks", for longer periods of time. What exactly causes this is not fully understood.
- Eating protein causes diet-induced thermogenesis (DIT), a shift in the metabolism of the body, which helps increase the amount of weight loss for dieters. However, one of the most effective types of protein to create this shift are the milk proteins, something not allowed in the paleo diet.
- The texture of meat and the associated work done by the jaw produces more sense of satiation.
- Protein and fat take longer to digest, leaving the dieter with a sensation of being "full" for a longer period of time.
- Simple carbohydrates, specifically processed sugars, cause insulin peaks and crashes, causing the dieter's body to react with a mental desire to eat, and often a physical sensation of being tired, weak or shaky. There are also some indications that these ups and downs affect how the body processes and stores the fats that are in the bloodstream.
Nevertheless, it is worth noting that the paleo diet, even in a 'high meat' form, is not necessarily high in protein. While meat is obviously protein rich, by excluding grains and dairy, the paleo diet removes significant sources of protein in the standard Western diet. For example, a 2500kcal diet based exclusively on whole-wheat bread will provide more protein than one and a half pounds of beef steak. Various dietary trials of paleo diets show little if any difference in protein intake between diet groups. One study also found the paleo diet produced more satiety per calorie, compared to a Mediterranean diet, which was not accounted for by differences in protein intake.
Paleo diets, in contrast to high protein diets such as the Atkins Diet and the South Beach diet, also include relatively high quantities of fiber, which, like protein, adds to satiety. However, again, in a trial comparing the paleo diet to the Mediterranean diet, there was little difference in fiber intake between groups (the Mediterranean diet contained more fiber in absolute terms), but fiber was not significantly associated with satiety across the two groups.
 Evaluation of claims
Losing weight can be hard. In the modern world, we sit most of our work day, drive or ride a bus home, use elevators and escalators to ascend, and have so many sports to watch on TV. We have to "work in" our exercise, and schedule trips to the gym usually between January 2 and January 15. We have little time or desire to cook, so we eat crap, drink liquid sugar, and give in to cravings because the convenience store is just around the corner. For these reasons, dieting offers much scope for scams and woo; semper caveat emptor. Does the paleo woo work, and is it based on science?
 Nutritional claims
Loren Cordain, Ph.D., author of a version of this diet, Exercise Physiology, claims that the diet is as healthy in nutrition as you can get. It is important to note at the outset that Cordain is an exercise physiology specialist, not a nutritionist - while not a neonate to the field, her expertise is tangential to the topic.
She and other advocates argue that due to the restrictions of her diet and the satiety afforded by the allowed foods, dieters consume fewer carbs (especially simple carbs such as sugar), and fewer calories total. Indeed, research shows that a diet limited in sugar and processed foods (which the paleo diet necessarily is, since processing is a neolithic thing) will generally help you lose weight. Grains, especially bread and desserts, are top sources of calories in America. Cutting them out will naturally lower one's calorie consumption drastically. Reviewing members of a blog's posts at their site and putting their day's foods into a calorie calculator shows something hardly surprising: the consumed calories are generally between 1200-1500 kcals, which is what is advised by the USDA for weight loss for women. Granted, one doesn't have to count calories by following this diet, but it's dubious that the weight loss is from the "type" of foods, and not just the amount.
In principle, none of this is unique to eating "paleolithic" foods, and nothing suggests that the body cannot handle foods we've sourced in the last 100,000 years — in proper amounts, at least. But the fact that Paleo dieters seem to have an easier time consuming fewer calories than the average American suggests that, in practice, this diet confers some psychological advantages versus a diet high in simple carbs.
Further, those attempting to follow the recommendation of this diet to eat only grass-fed ruminants, pastured poultry, etc., may find it so difficult or expensive that they end up eating the same animals as the rest of us.
Experts the world over say all diets boil down to how much energy we take in versus how much we expend, and we simply cannot escape that. To that end, it is possible to lose weight eating only Twinkies, and gain weight eating only carrots. However, the advantage of a paleo diet, like any other diet that emphasizes unprocessed foods, is in the satiety: dieters can lose weight without having to meticulously count calories.
 Medical claims
Dr. Cordain has also suggested that because it is generally low in fat, and that wild foods have a generally low glycemic index (also a popular diet buzz word), it will prevent illness from "modern diseases" (such as diabetes mellitus type II).
The stated assumptions at sites that suggest following this diet are that "cavemen were healthier" and did not suffer the kinds of ailments that Modern Man suffers from, and that most inexplicable illnesses (autism, cancer, arthritis, etc.) come from eating foods the body cannot process.
Despite Dr. Cordain's and others' assertions, nothing at all exists in the scientific journals to support claims that a paleolithic diet prevents acne, "inflammation" (another new woo word in woo medicine), athletic performance, or other authors' claims about autism, multiple sclerosis, or arthritis.
It is effective for heart disease, diabetes, and weight loss — however, no more so than any other reasonable low-fat, lower carb diet.
 Genetic and evolutionary
|“||There is this caricature that organisms evolve until they get to a point when they're perfectly adapted to their environment, then heave this big sigh of relief and stop. Anything that happens to them after that is disastrous.||”|
Proponents claim that the human digestive system is adapted to the diet of the paleolithic era and has not evolved since, and that the widespread incidence of diabetes and other diseases can be traced to the shift to a grain-based diet due to the advent of agriculture. This claim is not widely accepted, if at all, within mainstream science. Indeed, evidence suggests that humans have evolved over the last five thousand years specifically to eat an agricultural diet, including changing from a straight-on cutting bite to a shearing overbite. Further, the basis of the idea that we have not changed genetically does not take into account modern genetic studies nor modern theories of evolution.
Its proponents believe the "caveman diet" is the way humans were intended to eat — ignoring the fact that cavemen used much more energy than a modern human to gather food, and thus evolved a taste for foods with the most calories and fat, essentially making the caveman "diet" do the opposite of what it is intended for. In fact, for much of human existence, the wealthy became fat and their obesity was respected as a sign that they could afford to eat well and did not have to perform hard labor. The diet also ignores the fact that scientists have found traces of grains in fire pits from the earliest of humans, as well as evidence from "modern" hunter gatherers that tubers and legumes make up a rich part of their diet.
An interesting question of resource logistics comes up when discussing this diet. According to many scientists familiar with issues of world food supply, such as Norman Borlaug and Lester Brown, it is only because of a grain-based diet that the Earth can sustain 7 billion people.
LewRockwell.com has carried numerous articles promoting the paleo diet to libertarians, on the grounds that a grain, dairy, and sugar based diet is the product of big government and government-privileged agribusiness. On the far left side of anarchism, the diet has some interest among anarcho-primitivists with Lierre Keith's The Vegetarian Myth being the most influential book, arguing that agriculture is harmful to the planet.
Apart from the right and left fringes of anarchism, the diet does have a more mainstream political appeal among those who see it as a blow against political correctness and perhaps as a counter to veganism and vegetarianism. Nourishing Traditions: The Cookbook that Challenges Politically Correct Nutrition and the Diet Dictocrats by Sally Fallon, while not a strictly paleo cookbook (it allows for whole grains, legumes and promotes raw milk), could be described as semi-paleo and is currently quite popular.
 Woo debunked
The majority opinion of anthropologists seems to be that any information we have about what our ancestors were eating is insufficient to determine what a diet "based on their lives" would be like. In addition, the paleo diet doesn't make much sense, as diet varied by location as humans adapted to local conditions. Further, the same research questions how "healthy" humans could have been 100,000 years ago, when they were dying at a much younger age, generally malnourished (as seen by bone samples and hair samples), and often starving, simply due to the difficulty of acquiring foods. 
Basing one's diet on a people who were often starving, had to spend days tracking and hunting for the foods they ate, who would eat almost anything during the harshest of times, and had short lifespans, high infant mortality, and generally harsh lives seems a bit extreme for simply losing weight, and is very likely fully unhealthy. At a minimum, it must be admitted that paleolithic man had eating habits and requirements that were dramatically different from modern man, who exists in an environment that is much more rich in available calories, leisure time, variety of foods, and lifespan. Because of this essential logical difficulty and the dearth of research support, eating like a caveman is not likely to be the healthiest option.
 See also
- Paleo diet compilation site
- Must-Read review — if only for her humor
- The Paleo Diet: Caveman Cure-All or Unhealthy Fad?, The Atlantic
- The Paleo Diet…Do It Like the Cavemen Do, TheFoodFarce.com
- ↑ http://thepaleodiet.com/published-research/
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/19209185
- ↑ http://www.nature.com/ejcn/journal/v62/n5/abs/1602790a.html
- ↑ http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=17583796&dopt=AbstractPlus
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/19604407
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/21118562
- ↑ http://www.archevore.com/panu-weblog/2011/3/30/paleo-20-a-diet-manifesto.html/
- ↑ http://huntgatherlove.com/content/paleo-20-rational-response-inanity
- ↑ http://paleodietlifestyle.com/fatty-meat-potatoes-dairy-and-paleo-2-0/
- ↑ http://freetheanimal.com/2012/02/synthesis-low-carb-and-food-rewardpalatability-and-why-calories-count.html
- ↑ http://www.staffanlindeberg.com/TheKitavaStudy.html
- ↑ 1000 Inventions and Discoveries by Roger Bridgman in association with the Smithsonian
- ↑ For example, 
- ↑ Loren Cordain (The Paleo Diet)
- ↑ http://www.robbwolf.com/faq/#overview
- ↑ http://www.archevore.com/get-started/
- ↑ http://www.marksdailyapple.com/soaked-sprouted-fermented-grains/
- ↑ http://tribecalledfit.wordpress.com/2010/01/13/the-argument-for-lacto-paleo/
- ↑ http://tribecalledfit.wordpress.com/2010/01/13/the-argument-for-lacto-paleo/
- ↑ 
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/18469287
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/18769212
- ↑ med
- ↑ Neuropeptites and the regulation of appetite
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/22284175
- ↑ Effect of milk proteins on DIT
- ↑ Digestion rates of carbohydrates in women
- ↑ http://www.discoveryeducation.com/diabetes/pdf/Lesson2.pdf
- ↑ BBC, The Truth about Exercise
- ↑ http://nutritiondata.self.com/facts/baked-products/4876/0?quantity=10
- ↑ http://nutritiondata.self.com/facts/beef-products/3689/2?quantity=1.5
- ↑ http://www.springerlink.com/content/h7628r66r0552222/
- ↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2724493/?tool=pubmed
- ↑ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3009971/?tool=pubmed
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/7498104
- ↑ Colorado State University
- ↑ http://www.amazon.com/Paleo-Diet-Weight-Healthy-Designed/dp/0471267554
- ↑ Health.gov
- ↑ http://www.paleodietblog.com/
- ↑ 
- ↑ Not that counting calories is that difficult.
- ↑ Hunted wild game is generally quite low in fat, though I'm guessing few following this diet are hunting wild game.
- ↑ http://www.webmd.com/diet/features/diet-review-the-caveman-paleo-diet
- ↑ In writing this article, I searched Pubmed for "paleolithic diet"
- ↑ http://paleodiet.com/
- ↑ http://www.ncbi.nlm.nih.gov/pubmed/20144375
- ↑ George, Alison. "The Paleo Diet Is a Paleo Fantasy," Slate
- ↑ Hemochromatosis: a Neolithic adaptation to cereal grain diets. Naugler C.
- ↑ Molar macrowear reveals Neanderthal eco-geographic dietary variation. Fiorenza L, Benazzi S, Tausch J, Kullmer O, Bromage TG, Schrenk F. PLoS One. 2011 Mar 18;6(3):e14769.
- ↑ Ströhle A, Wolters M, Hahn A (January 2007). "Carbohydrates and the diet-atherosclerosis connection—More between earth and heaven. Comment on the article "The atherogenic potential of dietary carbohydrate"". Preventive Medicine 44 (1): 82–4. doi:10.1016/j.ypmed.2006.08.014. PMID 16997359.
- ↑ Lester Brown is the founder of the Worldwatch Institute and the author of dozens of books on world food logistics. Norman Borlaug was known as the "father of the Green Revolution" whose work was in plant genetics developing high-yield varieties. While the two had important differences, both of their works assume a grain-based diet as the norm, and the need to continually increase grain output or distribute it more equitably, as well as limiting further population growth, as necessary to solve hunger.
- ↑ http://www.lewrockwell.com/orig11/wiebe1.1.1.html
- ↑ http://lewrockwell.com/decoster/decoster183.html
- ↑ Utne Reader: Keith Goetzman, "Are Vegetarians Living a Lie?"
- ↑ Frank W. Marlowe. Hunter-Gatherers and Human Evolution. Evolutionary Anthropology 14:54 – 67 (2005)
- ↑ http://onlinelibrary.wiley.com/doi/10.1046/j.1467-3010.2000.00019.x/abstract;jsessionid=4C98D86001E7A23EA1A290C16A7E437F.d01t04