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I am a politically-progressive, ethically-herbivorous anthropoid pursuing a paleontology education in the Los Angeles Basin. I am largely nocturnal, have rarely been photographed, and cannot thrive in captivity.

03 November 2011

The Great Paleo-Diet Debunking That Wasn't

I've been getting a lot of emails about anthropologist Barbara J. King's critique of the paleo diet on NPR last week. I have to admit, I was intrigued: I've long been rubbing my mittens over the prospect of an expert on human evolution giving the paleo-eater crowd a swift kick in the loincloth. So, I penciled in some free time between my human mate-choice experiment and my ecology final project, took a few soothing deep breaths of anticipation, and sat down to savor some fresh thinking from a rigorous skeptic.

What I got instead was a shibboleth-rattling worthy of the finest witch doctors. Now, I expect this kind of hand-waving from the post-modernism-clouded minds of the cultural anthro crowd, but I thought King was a biological anthropologist. I was hoping for at least a few points about biochemistry and fossils, comparative anatomy and hominoid baggage. Heck, even a few leading questions, however misleading, about endogenous cholesterol production or amylase or eneterohepatic B12 recirculation would have been nice.

But come on, this? A missive that barely rises above the quality of evidence or logic in a typical blog comment from the president of the local high school vegan club?

I'm still reaching for the Excedrin.

It's not that King isn't making some valid points about hominid evolution. On a superficially factual level, much of what she says about that subject accords with what I've been taught, and what you'll read about in the paleo-anthropological literature.

It's just that she hasn't written a critique of the paleo diet movement. King is attacking a straw man.

Don't get me wrong; I have my own problems with the paleo diet's fundamental claims. But, the way I see it, the first duty of a skeptic is to understand the opponent's case honestly, on its own terms. And King fails at this duty; whatever else she thinks she is critiquing here, it's not the paleo diet movement I've come to know since I started this blog.

I spend some of my spare time lurking on paleo blogs, commenting on articles or videos here and there, but generally just trying to get a feel for what the movement is really all about. And it's obvious to me that King hasn't done this, or at least that she wasn't paying sufficient attention when she tried to do so.

For one thing, she seems to confuse the paleo movement with the low-carb movement. True, there is some overlap between the two groups, but paleo-eating isn't necessarily, or even primarily, carb-phobic. Some paleo bloggers defend high-carb diets similar to that of the Kitavans.Others are quite fond indeed of high-fruit eating plans. On the whole, low-carb isn't essential to the paleo philosophy.

What unites the paleo movement, food-wise, is an aversion to grains (especially refined) and refined sugars. Basic paleo doctrine is that the Demon Grain is out to get you, and if you're not careful, you'll end up with wheat belly or celiac, or both. It's true that grain products are high in carbs, but not all carbs are grains, and King -- a biological anthropologist, remember -- should not need an anonymous undergrad blogger like me to remind her of this.

For another thing, her remarks about the unsustainability of paleo-eating in a world of 7 billion people miss the point, too. Few paleo-eaters adopted the diet out of ethical or environmental concerns, as far as I can tell; most seem motivated primarily by personal health and a nebulous notion of "optimality." And further, though most paleo-eaters are enthusiastic about their diet choices, few of them make universalist claims or say that it is a blueprint for global civilization. Quite the contrary, politically-conscious paleos have a distinctly locavore bent, while most paleo blogs I've ever read are distinctly apolitical, avoiding global-ethics questions like wheat with the plague, unless some snotty vegan tries to corner them on the subject.

This is not to say that the paleo-diet's claims don't carry global ethical implications, even ones they may not see; but, an ethical critique of the movement would at the very least need to spell these implications out, rather than pretending that it's explicitly based on ethics or politics. And in any case, by taking this approach, King is lending her scientific credentials to a set of ethical claims that don't necessarily follow from her expertise. It's pure appeal-to-authority.

For a third thing (are we done yet?), King's scientific point misses the mark by almost an entire epoch:
Our ancestors began to eat meat in large quantities around 2 million years ago, when the first Homo forms began regular use of stone tool technology. Before that, the diet of australopithecines and their relatives was overwhelmingly plant-based, judging from clues in teeth and bones. I could argue that the more genuine "paleo" diet was vegetarian.
She seems to be unaware that the "paleo" in paleo-diet is short-hand for "Paleolithic," not a general attempt to co-opt all of paleo-anthropology in the service of a fad diet. The paleo diet's focus is, for the most part, precisely on the period of time she attempts to hand-wave away by diverting the reader's attention to the Pliocene. Again, the paleo movement's claims about and extrapolations from the Paleolithic may be pseudo-science, but leading us back before the Paleolithic in this way does nothing to demonstrate why.

King's tactic here glosses over the significant morphological changes of the last 2.6 million years, that paleo adherents consider supremely important. It is certainly true that H. sapiens retain within themselves the 22 Ma-old basic hominoid body plan for arboreal omni-frugivory; but at the same time, we are none of us Proconsul any longer, or even Australopithecus. Much of what morphologically distinguishes the Homo clade from its forebears reflects greater exploitation of, and selection for, a more omnivorous trophic strategy. Bottom line: humans really are better at handling meat than other primates seem to be, at least among extant species.

Implying otherwise is an amateur mistake. While it's excusable coming from the president of the local high school vegan club, King really ought to know better than this. The veg*n cause isn't served by obfuscation, and doesn't depend on  paleo-fantasies. That humans can handle meat better than other primates does not mean we can't or shouldn't be vegans; after all, there's still all that hominoid physiology and biochemistry knocking around inside us (a point I think many paleo critics of veg*nism often forget), and we do share a capacity for suffering with other vertebrates that ought to inform our ethics.

On the whole, it just seems to me like King didn't do her homework, and relied instead on pop media reports (and perhaps even the blasphemous Wikipedia) to inform her about the paleo diet movement. The result, though I doubt she intended it, is a dishonest misrepresentation of that movement. If I were on her graduate committee, I'd send this one back for revision.

King had a great opportunity here to skeptically examine the philosophical underpinnings of the paleo diet through the lens of evolutionary biology, and she blew it. Which is too bad, because her easily-refutable argument, coming as it does from an expert source, will leave many readers with the impression that there is no such critique to be made, and that scientists who object to its claims are merely agenda-driven.

The problem with the paleo-diet philosophy, from the perspective of evolutionary theory, is really a no-brainer: like some strains of veganism -- and indeed, like nearly all other "diets" -- it fetishizes food as both the problem and the solution. Almost without exception, paleo-eaters claim that the problem with "Neolithic" foods like refined grains and sugars is that these foods are at odds with our biology. We are not "designed" to eat them, and thus suffer the diseases of civilization as a result. Therefore, the claim goes, we should eat the way our Paleolithic ancestors ate.

And to be sure, some foods are worse -- a lot worse -- for us than others, at the level of individual health. But that's not because those foods are at odds with our biology so much as that they are in accord with our instincts.

See, contrary to what paleo-eaters claim, modern humans do eat the way our ancestors did. In fact, we eat exactly the same way they did; that's precisely the problem. Humans are instinctively driven to eat as much as we can when food is plentiful, so that we can build up and store fat as an insurance policy for lean times. And we are biased towards calorie-dense foods whenever they're available, because they give us the biggest payoff for the least work.

This makes perfect sense for us, given the context of our evolution. It's a great strategy when your chief concerns are avoiding starvation/predation, but absolutely shitty when safety is assured and food is overabundant. And even more so when the food that takes the least effort to procure is also the worst for you.

This strategy is older than humans, older than primates, older even than mammals. It's been the way of all animal life since at least the Cambrian explosion. And it's this deep-time perspective the paleo-diet lacks.

The diet works for the same reason that all well-designed diets work: because it gets us to reign in our instincts, to eat against the grain (pun intended) of our natural ways. To exercise some discipline in food choices, rather than simply following where our instinct leads us. "Paleo" diets are a completely modern response to a completely modern phenomenon: the intersection of our natural gluttonous instincts with the rapid increase of physical safety and high-calorie food overabundance. It shares this modern status with veganism and all other diet plans, well-designed or not. In short, it really has no place calling itself "paleo" anything.

The "paleo" diet is as "Neolithic" as they come.

25 comments:

  1. Thank you for this. I always appreciate your thoughtful critiques and ideas.

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  2. We need a DELUGE of such clear thinking as this in our world today. Half-thoughts and emotional blockages lead to polarization, which prevents any problem from being truly solved.

    From dietary fat and carbs to climate change, obfuscation, sloppy thinking and self serving by industry, media, government and science have obscured from we, the people who FUND the government and much of science, the FACTS that we need to decide for ourselves what to then DO with the knowledge.

    I'm afraid many responsible positions in the world today are held by people like Barbara King. Exedrin is only a temporary fix! Thank you for being a whole-brain voice!

    My husband and I have definitively discovered that certain foods have an obviously negative impact on our health. I'm afraid most people use pharamceuticals to counteract food-induced symptoms rather than try a food elimination diet. Or pay attention to modulating that siren call to consume the dozens of calorie-dense foods marketed to them every day, some of which can, when highly processed, be extremely damaging.

    Unfortunately for many people, common but potentially damaging foods (such as grains and legumes, their oils, and excess fructose) often don't start producing symptoms 'til one is in their 40s or 50s. We found that a grain- and legume-rich and meat-light "healthy" diet was slowly sapping away our health on several levels. Ditching grains (except for a little rice, a la Perfect Health Diet), legumes, seed and grain oils, and sugar (but of course introducing pastured meat, coconut oil, pastured butter, more avocadoes, ghee, etc.) made an amazing difference for us.

    But we have not slammed the door on continued awareness and new data ... which is why I visit your blog periodically!

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  3. I think you are too harsh in your critique. Your three criticisms do not seem entirely warranted from my reading of the article.
    Critique number one that she confuses low carb with paleo seems off the mark as she clearly achnowledges the following at the beginning of her article: "It's best to clarify right off that leaders of the paleo-diet movement don't think monolithically. Lean meat and veggies take center stage, but the emphasis may vary in details..."

    Your second critique that she should not criticize the diet due to its anti-ecological implications simply because paleo dieters either don't pay attention to this or claim otherwise also seems to miss the mark in my opinion. Eating higher on the food chain is not something we can ignore if we want to avoid the worst ecological scenarios.
    And finally your last critique that she obscures evolutionary history in order to slam the paleo diet may be true, but you did not address her most forceful claim made in the following paragraph:
    "Here's where science most forcefully speaks back. First, ancient hunter-gatherer groups adapted to local environments that were regionally and seasonally variable — for instance, coastal or inland, game-saturated or grain-abundant (eating grains was not necessarily incompatible with hunter-gatherer living). Second, genes were not in control. People learned what worked in local context for survival and reproduction, and surely, just as in other primates, cultural traditions began to play a role in who ate what.

    Do you think this is faulty reasoning as well?

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  4. compostbrain,

    It's not that her reasoning is faulty, it's just that it doesn't address the actual paleo diet movement. This last point of hers you quote is a prime example. It's addressing a universalist claim that the paleodiet doesn't make. Paleo-eaters are already locavores for the most part, and would not disagree with her point at all. That she seems to think they would indicates she's not really familiar with the movement.

    I have no problem with subjecting the paleo diet to ethical scrutiny. One of my biggest criticisms of it, actually, is that it lacks an ethical component. However, that we can and should scrutinize it ethically does not mean that the paleo diet claims to have an ethical basis. Again, here King is attacking a straw man, as though the paleo diet makes ethical claims that she sought to counter.

    Her point about grain and livestock is a good example. Paleo eaters reject grain-fed meat for the most part, so lobbing this objection at them is insufficient without demonstrating how their demand/support for grass-fed meat will lead to increased grain consumption. She seems to just assume that paleos eat the same meat as everyone else, and that the point of the movement is "eat more meat." I used to make this mistake as well, so I can understand why King thinks this; however, she's a trained academic, and should have been more careful in her research.

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  5. Did you miss the new trend where paleo dieters are eating buckwheat and rice? A lot of the paleo bloggers are now. And the "Primal Wisdom" guy has basically gone back to veganism.

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  6. I agree with everything except for this: "Humans are instinctively driven to eat as much as we can when food is plentiful, so that we can build up and store fat as an insurance policy for lean times."

    Obesity is a modern disease and was not rampant 100 year ago. To suggest that we are eating too much food may need to be simplified into we are eating too much proccessed fiberless sugar filled garbage.

    "It will be noted that the fundamental difference in the present approach to obesity, from that based on the supposed faulty functioning of an 'appestat' centre in the brain, is that the appetite is not regarded as an enemy here, to be placed in a strait-jacket, but as a normal instinct, to be let loose on foods so naturally diluted by fibre that the instinct is neutralized in a natural manner. Hence the emphasis on crude wholemeal bread several days old, raw fruit such as the apple, and bulky vegetables, in the diet card just referred to." - TL Cleave

    Your body has a defense mechanism to protect you from eating too much wholesome food, its the hormone leptin. When leptin is low in the fat tissue your body signals you to eat, when leptin is high the appetite is suppressed so you don;t continue eating. The problem with industrial food is that it does not signal leptin and thus we develop leptin resistance and our body thinks it's starving and starts storing body fat at an excelerated rate. This was well documented in ancel keys starvation study, the individuals were subject to a famine they became very skinny and when food was made available again they become fat. However there weight eventually came back down and their appetites become normal but this process took almost a year. So even after the famine they went back to a lean state after being fatter for a small period of time. The body recognized that the famine was over and started buring fat and building up lean body mass.

    Basically, to suggest that because food is plentiful we get fat holds no weight. Have you ever seen an obese monkey or horse even when food in their enviornment is plentiful? Eating whole unrefined food will not make a healthy individual fat your body has no need to store extra fat when there is no sign of a famine and leptin is working properly.

    I guess I avoided the whole point of this post but o well I think understanding bio chemistry is much more important then speculating on what people ate a million years ago when we can clearly see that people were healthy 200 years ago. No need to demonize meat, grains, or god for bid ice cream.

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  7. Thank you for this awesome critique. When I read her article I was like, what paleo movement is she talking about? Because it isn't one I am familiar with.

    The statement "... the paleo-movement seems to doom (even if unintentionally) more animals to life and death in factory farms. A greater percentage of grain crops would also be diverted to rich countries' animals and away from poor countries' people." is, if you done any research into the recommended paleo diet, absurd.

    A huge part of the paleo thing is that we should be eating grassfed meat. Nobody is suggesting that grainfed and factory farmed meats are "optimal". If animals are grassfed by grazing on land that is not otherwise arable (as is common in the UK,New Zealand, etc), I don't understand who is losing out in that situation. Not to mention the fact that "rich countries" shipping their artificially cheap subsidised grain to "poor countries" actually destroys local economies and leads to people eating a subsistence diet with not much actual nutrition.

    The other thing I really object to is the idea that every diet should be something that every person in the world can follow. There is NO DIET that is replicable for seven billion people. We can't all eat a Japanese style fish and rice heavy diet. We can't all eat steak every day. We can't all eat tofu. We can't all eat lentils. Within the paleo movement there is actually a huge focus on local food and seasonality, much more than there is in the standard diet that most people in "rich countries" follow. Is eating locally grassfed meat really worse and less sustainable than flying asparagus in from Peru? Really?

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  8. HH, It is a short article and she does not go into detail explaining all of her claims but I didn't get the impression that she thinks that paleo's are recommending grain fed meat. She saying the consequences of more people eating higher on the food chain means more overall meat production. Since the majority of animal agriculture feeds grain to animals, it cannot be avoided that more grain will be fed to animals, regardless of paleo claims to favor grass fed.
    From my experience very little meat production is entirely grain free. Although I don't have any scientific studies showing this I would wager that the recent upsurge in small scale meat production has increased demand for grain. I have visited several small scale producers and not one had abandoned grain-based animal feed. For example, Joel Salatin, the guru of sustainable meat production, may be using more calories of grain entering the farm than leave the farm in the form of meat.
    (See this analysis: https://saywhatmichaelpollan.wordpress.com/2010/07/21/the-free-lunch/)

    While some paleo dieters may not claim an ethical basis, many do. See the comment above and Keith's book for prime examples. The majority of people want to believe that their diet is ethical. I don't think it is a straw man as you claim to argue against the ethical claims of some paleo dieters just because not all of them claim such a basis.

    The quote I mentioned in my previous post is in direct response to the most well known paleo writer. I don't agree that the majority of paleo followers would agree with her quote. None of the paleo followers I have met would endorse eating any grains and they all claim that our genes have programed us to live on a meat centered diet.
    Claiming she doesn't understand the paleo movement seems off base if you are relying on a few outliers for your claims.

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  9. That's because Salatin isn't doing grassfed meat, at least for some of his products. You can't do grassfed rabbit, chicken, or pork to sell commercially. So most of his meat is actually grain fed :) If he wanted to be grass-fed, he would produce bison, goat, or other ruminant meat.

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  10. Very honest critique.

    "See, contrary to what paleo-eaters claim, modern humans do eat the way our ancestors did. In fact, we eat exactly the same way they did; that's precisely the problem. Humans are instinctively driven to eat as much as we can when food is plentiful, so that we can build up and store fat as an insurance policy for lean times. And we are biased towards calorie-dense foods whenever they're available, because they give us the biggest payoff for the least work."

    As another commenter has pointed out, evolution afforded us with appetite regulation to prevent obesity even in the face of plentiful food (unless we're supposed to get obese, like a bear in advance of hibernation). Thing is, this stuff only works right in the face of real foods that our biochemistry recognizes. Hot Pockets, Pop Tarts, Pizza, Burgers, Fries and a soda have macro and micro-nutrient compositions that are 1) foreign to us and 2) specifically engineered to make us want more and more.

    "The diet works for the same reason that all well-designed diets work: because it gets us to reign in our instincts, to eat against the grain (pun intended) of our natural ways. To exercise some discipline in food choices, rather than simply following where our instinct leads us."

    In effect, yes, but I sense that you're placing most of the emphasis on willpower (whatever the underlying motivation: health, weight loss, ethical concerns, etc.). What I have found over 4 years at this thing from my own experience, that of many family members, and my blog at Free the Animal with thousands of readers and commenters is that we all _naturally_ reign in those instinct, which gets me back to the first point. When you eat real, nutritionally dense foods that your biochemistry recognizes, everything falls into place for most everyone. Exceptions are for people with severely damaged metabolisms, such as DM2s.

    But anyway, this was a fabulous post. Thanks.

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  11. Further to the idea that we get fat because of plentiful food and not necessarily industrially processed food.

    Consider the 8 sq mile tropical island republic of Naru, now known as the fattest place on earth. It didn't used to be so, and they had all the fish, coconut and other fruit they could eat, anytime they wanted. And they were lean.

    But then because of phosphorus mining, they got rich and instead of continuing in their traditional ways on real food, they began importing canned and boxed foodstuffs. They literally eat nothing fresh, anymore.

    Cool 6 minute ABC video:

    http://youtu.be/x-7rf9hz-Ko

    Now Occam's Razor suggests to me that the explanation with the fewest assumptions is that there is something about industrially engineered food that messes with both metabolism and satiation hormones and signals rather than they all suddenly just decided to begin eating way too much.

    That they ate more, i.e. calories, is probably not disputable, but why? Plentiful food was always available. What changed is that they went from having plentiful natural food to plentiful industrial food.

    I just wonder: is this not one of the greatest controlled & randomized experiments ever? Consider that this is the smallest island nation in the world at 8 sq. miles. You can drive its perimeter in about 20 minutes, in traffic. Population is around 14,000, and it's about 400 miles from the nearest commercial port from whence products may come.

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  12. compostbrain,

    So, how hard would it have been for King to say what you just did? And if her remarks about local variance were in response to a specific writer, she should have cited him or her by name. These are very basic mistakes.

    Her science response, though, was the worst. The paleodiet focuses on the Paleolithic (almost fetishistically, IMO), while King omitted it entirely. She should have addressed the movement's claims about the Paleolithic head-on, using the Pliocene and Miocene as the earlier context.

    Ignoring it the way she did gives the impression there's no scientific critique to be made.

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  13. Scott,

    The function of leptin is not the prevention of obesity. It mostly regulates the onset of maturity by mediating hormonal signals of adiposity, and its primary energy homeostatic function is the maintenance of adequate fat stores for times of starvation. Its anti-obesity effect is secondary, and probably selected against phenotypically, since starvation is a more common exogenous health threat than overabundance. Bascially, it tells the hypothalamus when the body has become fat enough to start puberty, and helps protect reproductive capacity by shutting it off during starvation and signaling the hypothalamus that it's time to tap fat stores for use in basic metabolic functions.

    Remember, evolution is primarily about sex, not food (one of the things that makes it so much fun!).

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  14. A quite famous paleo guy commented this critique too: http://freetheanimal.com/2011/10/another-simple-question-the-paleo-diet-is-not-the-way-to-a-healthy-future-for-whom.html

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  15. Richard,

    I take your point about Nauru, but look at what else changed: they lead a more sedentary lifestyle in addition to eating more calories.

    The fact that food was abundant to them during their H-G phase does not mean it was over-abundant. That only becomes true when energy surplus is the norm rather than the exception. The Nauruvians (???) now expend less energy procuring food than they did in H-G days, and the foods they eat are higher in calories. Net result: obesity.

    While I certainly agree that "industrial" foods (by which I presume you mean refined grain and sugar products, mostly) are worse from a health perspective than whole foods, I don't think it's the whole story. There are many people who do great eating such foods because they spend more calories than they eat.

    The chief deficit of these foods is cultural, in that they provide huge amounts of calories to humans in societies without a significant individual energy cost of food procurement. Also, they are often digested more quickly than whole foods, and many of them are designed to activate our hunger response. Far from being averse to our biochemistry and instincts, they are destructively attuned to both.

    Our way of eating hasn't changed, only its context.

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  16. Thanks for the great post!

    Regarding your point, "Our way of eating hasn't changed, only its context." So true. For a fantastic book on the subject check out: Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose-by Deirdre Barrett.

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  17. Thanks for the link love. Solid post and comments. Sorry, don't really have anything else to contribute.

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  18. Interesting read

    It should be noted though that Don Matesz was originally a true high fat/high protein/low carb Paleo exponent.. before his health and that of his wife and patients (he's a practising nutritionist) got worse on that diet.. then cognitive dissonance ensued and he found the solution in a mostly mcdougall style low fat- high carb diet. It's a great rebuttal to the omni prescient paleo /low carbers out there... and he is scientifically pretty sound..

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  19. I've long suspected, that the only thing wrong with modern diet is simply too much food per unit of exercise. I have a healthy friend in his mid-50s who will eat 8K calories a day of virtually any food when he is biking cross country. He loses weight and feels great. But when not exercising has to cut way back. The problem with a snicker bar is that it gives you so many calories without in any way making you feel full.

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  20. I also agreed with GaryB that with diets you should also do your exercise daily.

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  21. Paleo Diet is basically what our ancestor used to eat millions of years ago,
    before agriculture came into existence . It is also referred as “Hunter’s Food” as they used to gather it from here and
    there by hunting animals or collecting from plants and trees paleo diet

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  22. I am mansi saxena, I am also a web designer and I like your blog too much the colors and themes are really nice.
    The Paleo diet is the healthiest way you can eat because it is the ONLY nutritional approach that works with your genetics to help you stay lean, strong and energetic!
    Research in biology, biochemistry, Ophthalmology, Dermatology and many other disciplines indicate it is our modern diet, full of refined foods, trans fats and sugar, that is at the root of degenerative diseases such as obesity, cancer, diabetes, heart disease, Parkinson’s, Alzheimer’s, depression and infertility.
    Do visit my blog paleo diet recipes

    ReplyDelete