Paleo diet



Something's just not right – our air is clean, our water is pure, we all get plenty of exercise, everything we eat is organic and free-range, and yet nobody lives past thirty. A paleo diet is one based on the premise that the optimal diet is that of our evolutionary ancestors during the paleolithic era when the estimated life expectancy was 33 years. It is essentially an appeal to ancient wisdom fallacy. 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. Actual paleolithic-era diets were pre-agricultural, hence food was obtained from hunting and gathering. A paleo diet is typically based on eating only those foods that the adherent believes a hunter-gatherer society would have eaten, such as meat, nuts, berries, fish, vegetables, fruits, and tubers. Typically excluded are foods that are the products of large-scale agriculture such as grains, bread, dairy products (in some versions), legumes (beans, peas), and processed sugar and salt. The Paleolithic era in Europe lasted until roughly 12,000 BCE.

What paleo advocates call the paleolithic diet and what paleolithic diets actually were do not necessarily line up. For example, based on initial chemical studies of human bones from the Paleolithic era, it was shown that humans did eat a lot of animal protein. It was initially difficult to ascertain what else humans might have eaten then because plant material did not preserve well at such archaeological sites. A recent study of Balkan hunter-gatherers found that they gathered, processed, and ate wild starchy grains at least as early as around 11,500 BCE.

The "paleo diet", like most diets, has evolved over time and has many variants. Its earliest phase is associated with and is based around only paleo food-types, as above. It is the diet in this guise that has attracted the 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 are imagined to 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.

Description
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 societies as the Kitava People of Papua New Guinea who do practice agriculture and have a diet mainly consisting of tubers, fruit, fish and coconut. The life expectancy for the Kitavans is only 45 years but this is mainly due to high infant mortality from malaria and other infections; excluding infant mortality, the life expectancy is unknown. Lindeberg's team looked at a specific set of health endpoints (blood pressure, anthropometry and serum lipoproteins) and noted that they might explain the apparent lack of stroke and heart disease. Harriet Hall concluded from the Lindeberg team results, "The Kitava Study provides food for thought; it doesn't provide enough justification to recommend either a Kitavan diet or a standard 'Paleolithic diet' over other healthy diets."

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 humans have 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 humans 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.

Much of the Paleo diet movement is focused not on the work of anthropologists but on that of Weston Price regarding the effects of modern (1920s-1930s) processed food on so-called primitive cultures who were seen as "living fossils" of neolithic societies.

What do paleo dieters eat?
As with any fad diet, the paleo diet comes in many varieties and ranges widely. In general, though, the following food guidelines 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. Hunter-gatherers living in coastal areas would likely have eaten reasonable amounts of fat from marine mammals they hunted as the Inuit do today.  Others would have eaten less animal fat.
 * The offal of the animals listed above.
 * (whale skin and blubber) presumably, though probably not outside of Alaska.
 * 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. (However, some dieters commonly use sweeteners such as dried fruits, coconut, maple, and agave 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' or 'Primal'.

As with any woo, adherents vary as to 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 small amounts of unpalatable wine could in theory be "found" in naturally fermented foodstuffs. Actual wine and beer likely did not start until near the time of the advent of agriculture, i.e., post-paleolithic. 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 "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.

Small numbers of paleo dieters try a vegan or vegetarian version of the diet though most humans can only get vitamin B12 from animal products or from highly processed vitamin supplements.

What did paleolithic humans actually eat?
There’s a hefty dollop of irony in the possibility that original Paleo diets mixed what people in many societies today regard as gross-sounding portions of putrid meat and fat with vegetarian dishes that still seem appealing. Paleolithic humans adapted their diet depending on the season and on what food resources were available locally. Humans evolved to be flexible eaters. Studies of modern foragers indicate a wide range of diets, suggesting a similarly wide range among paleolithic peoples. Inuits subsist almost entirely on meat (and blubber); others living by the sea often eat mostly fish and shellfish; those away from the sea but with access to tubers or other vegetables or fruit will eat them. Early stone tools were used to process both animal and plant material. Mixing foods up from different parts of the world is a post-Paleolithic invention.

Actual Paleolithic diets had to include animals and plants that most Americans (who are the primary consumers of paleo woo) wouldn't touch with a 10-foot squeamish pole. Next time you meet a paleo, ask them if they eat:
 * Each other (and possibly Neanderthals) given that there is evidence of cannibalistic scavenging and even direct cannibalism among early human ancestors.
 * Small game — really small game — like rats, mice and squirrels.
 * Unpleasant plants, pre-selective breeding. Less-attractive versions of the nuts you find in your ice cream. Sour and bitter tastes existed in many plant foods before human interference. Although paleolithic humans probably avoided downright foul-tasting (and likely poisonous — the dose makes the poison) 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 are found in the genera Solanum (tomatoes, potatoes, peppers, eggplants) and Prunus (almonds, peaches, apricots, plums, cherries), and even bananas, which were formerly mostly seed. If you hated Brussels sprouts and broccoli as a kid, imagine how nasty they were before selective breeding, not that it would be better if you loved them too (sprouts, like other Brassica — cabbage, broccoli, cauliflower, kale, etc. — are the result of centuries of modification of the wild cabbage). Carrots were only grown for their leaves until around 1000 years ago, and orange varieties date from after 1600 ago. Many fruits, such as oranges, strawberries, and bananas have been greatly modified by hybridization and selective breeding to produce versions with smaller seeds, more fruit, and less bitterness (strawberries date to the 1750s). Safe varieties were likely discovered by just eating them and hoping it didn't kill anybody. They may have played "will it kill me" with wild fungi, but modern mushrooms (common/button, chestnut, portobello, and more) derive from a variety first cultivated in 1707 CE.
 * Woody stems, stripped bark, and pith: things suspiciously absent from the modern paleo diet that probably contributed to the extreme dental wear and tear observed in fossil individuals.
 * Organ meat — a critical part of paleolithic human's diet. Does the average paleo dieter (likely American) 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 (which the animals themselves were selectively bred for eating and are different from their ancestors).
 * Putrid meat, both raw, fermented or cooked — Historical accounts of hunter-gatherers and present-day hunter-gatherers in the modern-day arctic have relished eating putrid meat and fish.
 * Chyme — the stomach content of herbivores
 * Insects, especially grubs, beetles, and cockroaches
 * 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 America; they look nothing like the domestic type), 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. There is also evidence that paleolithic humans evolved extra amylase production to break down cooked starches, such as tubers, long before the advent of agriculture, suggesting that starchy food was already a diet staple.  Evidence of oat flour production more than 32,000 years old has been found (despite oatmeal being a big no-no on a lot of paleo diets). The oldest remains of bread dated to around 14,000 years ago, well before the birth of agriculture.
 * Fruits and nuts
 * Shellfish

If paleo advocate responds with "No, I don't eat some of that stuff," you've cornered them. They'll tell you that they don't eat insects because that would disgust them, but the real reason is that they have a faulty understanding of evolutionary reality, and if you want to act a little pretentious, you can also argue they don't appreciate the broad palate humans historically have. Or if you just like grossing people out, tell them that if they're eating fruits or vegetables that they're already eating insects, they're just not seeing them.

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 Diet, are popular for weight loss and have attracted a large amount of research.

Some reasons high protein diets work:
 * 1) When eating protein, the brain sends a hormone called leptin 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.
 * 2) 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 is the milk proteins, something not allowed in the paleo diet.
 * 3) The texture of meat and the associated work done by the jaw produces more sense of satiation.
 * 4) Protein and fat take longer to digest, leaving the dieter with a sensation of being "full" for a longer period of time.
 * 5) 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.

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 2500 kcal diet based exclusively on whole-wheat bread will provide more protein than 1-½ 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.

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 websites to surf. 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?

An expert summary of the peer-reviewed scientific evidence for and against the paleo diet found that "the Paleo diet is not a miracle diet and several of the premises of the Paleo diet are not supported by evidence."

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 dietician — while not a novice in the field, his expertise is tangential to the topic. Some of his advice is dubious. Cordain advises making a salad, storing it and eating a bit with extras every day for a week. By day two the salad will have lost its vitamin content; by the end of the week there may be a dose of the germs, a real-hunter gatherers' encounter. Here is what a website that understands food hygiene recommends. "Store leftovers in the fridge within two hours of cooking and eat them within three days." A bout of food poisoning could lead to dramatic weight loss as claimed.

Cordain and other advocates argue that due to the restrictions of his 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.

It's commonly said that diets boil down to how much energy we take in versus how much we expend. Calories in versus calories out, however, is extremely reductionist, as nutrients and food composition matter more. While it is technically possible to lose weight eating only Twinkies, and gain weight eating only carrots, it is much more difficult since carrots are not calorie dense yet they are more filling by being fiber rich, requiring more time to chew, and requiring more time to digest as opposed to a Twinkie which takes considerably less effort to digest, does not satiate as long, is dense in cheap carbs and sugars, and has no nutrients. Thus, the advantage of a paleo diet, like any other diet that emphasizes unprocessed foods, is in the satiety: dieters can lose weight and stay satisfied without having to meticulously count calories.

In U.S. News and World Report's 2013 annual review of about 30 popular diets, conducted by a panel of around 30 nutrition and medical experts, the paleo diet ranked close to the bottom in 6 different metrics.

Medical claims
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 help to prevent illness from "modern diseases" (such as diabetes mellitus type II). Real food scientists note glycemic load is based on realistic portion sizes and is therefore more significant than glycemic index. The glycemic load from baked potato is as high as that from sugary drinks.

The stated assumptions at websites 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 and disabilities (autism, cancer, arthritis, etc.) come from eating foods the body cannot process.

Despite Cordain's and others' assertions, little evidence exists for the benefits of paleo diets in the scientific journals to support claims that a paleolithic diet prevents acne, "inflammation" (another new woo word in woo medicine) or improves athletic performance. Other authors' claims about autism, multiple sclerosis, or arthritis are also unsupported.

Note: Not all variants of the paleo diet are low in fat. Some extol the virtues of saturated fat, particularly in the form of untrimmed red meat, full-fat dairy, and coconut oil. Cordain's assertions about the healthy, low fat nature of "the" paleo diet clearly aren't talking about these high-fat variants.

Paleo diet is effective for heart disease, diabetes, and weight loss. However, it is not more so than any other reasonable low-fat, lower carb diet.

Preliminary research on mummies, from ancient cultures around the globe, suggests that rates of atherosclerosis (plaque lining blood vessels) were not significantly lower back then. Randall Thompson, cardiologist and professor at the University of Missouri-Kansas City School of Medicine, states:

At least one death has been attributed to a high-protein diet, in the case of a woman with a rare genetic disorder (urea cycle disorder).

Genetic and evolutionary
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. 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. There is evidence that in Europe, farmers out-competed and eventually replaced hunter-gatherers with minimal interbreeding.

In fact, humans have, only to a certain degree, adapted to a diet based on agriculturally-produced foods. Milk intolerance is a condition where adults cannot digest and absorb lactose. This condition is common in Europe and normal in at least some Chinese populations. Over 90% of Chinese adults cannot digest or absorb lactose fully. China had an agricultural system for thousands of years but most Chinese adults have not evolved the ability to make full use of the milk that their dairy animals produce.

Towards the end of the Paleolithic era, during the Pleistocene (c. 10,000 BCE), human genes changed in response to increases in cooked carbohydrates in the diet. The effect of this cooking was to increase digestibility of starches, and had the effect of facilitating the increased metabolic demands of larger brain sizes, red blood cells and fetal development.

Loren Cordain advised against milk based on what he calls "an impressive study", though the author of the study and the UK NHS call it a preliminary study which does not provide firm conclusions. Cordain suggests eating bone meal to increase calcium intake. However, lead and mercury are present in bones from western nations, and the human variant of mad cow disease could be transmitted through bones.

Present-day humans cannot go back to a paleolithic-era diet because they do not live in a paleolithic environment. Our foods are different. For people on a Western diet who can digest milk, leaving it out may be harmful. High-protein diets (like some meat-based paleo diets) can lead to the body excreting calcium which gets depleted from bones. Those who follow the [paleo] diet may be missing out on vital nutrients, and it is believed that could create long term health problems, in particular for adolescent girls who may be at risk of developing osteoporosis later in life as a result of not getting enough calcium.

Proponents of the paleo diet 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 richest in 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.

While not evolutionary strictly speaking, there is evidence that the effect of eating an agriculture-based diet has an effect on dental overbite. Hunter-gatherers tend to have top and bottom teeth that align whereas agriculturalists tend to have an overbite with the top row of teeth protruding in the front. This would be due to the tougher-to-chew diet of hunter gatherers (game meat and wild plants). One consequence of this is that the languages of agriculturalists tend to have ("f" and "v" in English) in their languages whereas such sounds occur rarely among the languages of hunter-gatherers. Labiodentals are difficult to pronounce without having at least a slight overbite. So if you are actually stupid enough to raise your children on an authentic paleo diet, they may not have an overbite when the grow up and may have difficulty pronouncing labiodentals.

Political
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), it 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, since 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. Atherosclerosis was less common in primitive societies than in industrial societies but it happened. Surviving long enough to develop atherosclerosis was also far less common in hunter gatherer societies.

Basing one's diet on 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 humans had eating habits and requirements that were dramatically different from modern humans, who exist 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 prehistoric person is not likely to be the healthiest option.

Assumptions about paleo diets commit a fallacy which is common in nutrition, namely to assume that a person or group's diet, in isolation from their lifestyle, is responsible for their state of health. Even if we did assume that paleolithic humans had a diet which was ideal for them (although all evidence suggests otherwise, as described above), applying the same diet to a modern lifestyle would not necessarily be ideal. In other words, if you want to have the health of a caveman (and why would you?), you have to live like a caveman, not just eat like one.