The Paleo Diet.

by Loren Cordain.

Preface to the Revised Edition

The original version of The Paleo Diet The Paleo Diet first came into print in January 2002. After its initial release, my book gained popularity and sales were good for the next few years, but it did not achieve chart-topping levels and the national exposure for which I had hoped. Fast-forward eight years to 2010: first came into print in January 2002. After its initial release, my book gained popularity and sales were good for the next few years, but it did not achieve chart-topping levels and the national exposure for which I had hoped. Fast-forward eight years to 2010: The Paleo Diet The Paleo Diet has become one of America's best-selling diet and health books. has become one of America's best-selling diet and health books.

This kind of sales history is almost unheard of in the publishing industry for successful diet books, which typically act like dwarf stars-they burn brightly at first and then fade away. Not so for The Paleo Diet The Paleo Diet, which started as a gentle glow and over the years has become hotter and hotter until now it is red hot. A diet book that once began as a ripple is now approaching tidal wave proportions.

Why? What is different about The Paleo Diet The Paleo Diet in 2010 compared to 2002? The material in the book has not radically changed, but the world has radically changed since 2002, particularly how we now communicate and inform one another about our lives, our daily experiences, and our reality. And herein is a clue to my book's sustained and increasing popularity. in 2010 compared to 2002? The material in the book has not radically changed, but the world has radically changed since 2002, particularly how we now communicate and inform one another about our lives, our daily experiences, and our reality. And herein is a clue to my book's sustained and increasing popularity.

When I first started to write The Paleo Diet The Paleo Diet in 2000, the Internet was in its youthful throes (Google had been founded only two years earlier, in 1998), and most people still used telephones (not cell phones) to talk. The U.S. Postal Service remained healthy because Bill Gates's foundational maxim "a personal computer in every household" had not yet taken firm hold, and snail mail reigned supreme. Then, "spam" simply meant canned meat. In the era of my book's baptism, texting, blogs, Facebook, YouTube, and most of the other Internet and electronic wizardry we now routinely take for granted still lay in the future. Then, people found out about the world through newspapers, radio, TV, and weekly news magazines. Now, except for the in 2000, the Internet was in its youthful throes (Google had been founded only two years earlier, in 1998), and most people still used telephones (not cell phones) to talk. The U.S. Postal Service remained healthy because Bill Gates's foundational maxim "a personal computer in every household" had not yet taken firm hold, and snail mail reigned supreme. Then, "spam" simply meant canned meat. In the era of my book's baptism, texting, blogs, Facebook, YouTube, and most of the other Internet and electronic wizardry we now routinely take for granted still lay in the future. Then, people found out about the world through newspapers, radio, TV, and weekly news magazines. Now, except for the New York Times New York Times and a few other mainstays, daily newspapers have dried up to a trickle. Who wants to hear about outdated weekly news in paid-for magazines when you can get it for free and instantly from the Internet anytime you want? Like newspapers and magazines, radio and TV are not nearly as convenient or as timely as the Web-you can get Web versions of these media, anyway-so why bother with the real things? and a few other mainstays, daily newspapers have dried up to a trickle. Who wants to hear about outdated weekly news in paid-for magazines when you can get it for free and instantly from the Internet anytime you want? Like newspapers and magazines, radio and TV are not nearly as convenient or as timely as the Web-you can get Web versions of these media, anyway-so why bother with the real things?

When I wrote The Paleo Diet The Paleo Diet a decade ago, electronic interconnectedness was primitive, slow, and noninclusive. Local U.S. news was unavailable, obscure, or unknown in places like Uzbekistan or Botswana and vice versa. In those days, scientists reported new discoveries in their specialized journals, but this information was rarely picked up by newspapers or the popular press. It took years or decades for many discoveries to have an impact on people's lives. A decade ago, most people didn't argue with their physicians' diagnoses and prescriptions because "the doctor always knew best"-presumably because, then, the doctor was better informed than the patient was. a decade ago, electronic interconnectedness was primitive, slow, and noninclusive. Local U.S. news was unavailable, obscure, or unknown in places like Uzbekistan or Botswana and vice versa. In those days, scientists reported new discoveries in their specialized journals, but this information was rarely picked up by newspapers or the popular press. It took years or decades for many discoveries to have an impact on people's lives. A decade ago, most people didn't argue with their physicians' diagnoses and prescriptions because "the doctor always knew best"-presumably because, then, the doctor was better informed than the patient was.

The Internet, Web sites, blogs, cell phones, and other various types of electronic wizardry have transformed our world within a mere decade or less. The electronic transmission of news and information and practical data to improve our lives, our financial situations, and our health has become humankind's universal language. Anyone in the world who has access to either a computer or a cell phone can immediately connect with anyone else who has the same technology. We now can and do talk to one another in unprecedented numbers-by the billions. A local event can instantaneously become a worldwide happening. Today what your next-door neighbor knows is available not only to you and your close friends, but literally to the world.

With such vast and nearly total information connectiveness, a subtle but crucial upshot of this brave new electronic world has arisen. When someone comes up with an answer to a complex or even a simple problem that is correct and that works, it gains followers like a s...o...b..ll rolling downhill. Such has been the case for The Paleo Diet The Paleo Diet. It simply works. In an earlier era, prior to the Web, when human networks were small and noninclusive, information flowed slowly or not at all. Accordingly, correct answers sometimes smoldered for years, decades, or longer before they became widely recognized and accepted. Fortunately, The Paleo Diet The Paleo Diet came of age at the same time that the Internet was being adopted globally. came of age at the same time that the Internet was being adopted globally.

Had I originally written about a diet-a lifetime way of eating-that didn't work, The Paleo Diet The Paleo Diet would have simply faded into oblivion in the ensuing eight years since its publication. Yet it didn't. My book continues to gain more and more supporters as people like you relate their personal health experiences with would have simply faded into oblivion in the ensuing eight years since its publication. Yet it didn't. My book continues to gain more and more supporters as people like you relate their personal health experiences with The Paleo Diet The Paleo Diet to one another via the largest and most comprehensive human network ever created: the Internet. If to one another via the largest and most comprehensive human network ever created: the Internet. If The Paleo Diet The Paleo Diet had caused you to gain weight, made you feel lethargic, raised your blood cholesterol, promoted ill health, and been impossible to follow, it would have fallen by the wayside like most other dietary schemes dreamed up by human beings. Yet it didn't. In fact, had caused you to gain weight, made you feel lethargic, raised your blood cholesterol, promoted ill health, and been impossible to follow, it would have fallen by the wayside like most other dietary schemes dreamed up by human beings. Yet it didn't. In fact, The Paleo Diet The Paleo Diet movement continues to spread worldwide, thanks in part to the Web. movement continues to spread worldwide, thanks in part to the Web.

When people find correct answers to complex diet/health questions, they let their friends know, and thanks to the Internet, the momentum has accelerated. In the United States, the word "Paleo" has become part of ma.s.s culture, due in part to its popularity with the national CrossFit movement that is sweeping the country and recent coverage in the New York Times New York Times, the Washington Post Washington Post, and other global media. The Paleo Diet The Paleo Diet has found wide acceptance not only with CrossFitters and athletes, but also with the medical and health professions, who have embraced it because of its wide-reaching therapeutic effects on metabolic syndrome diseases, autoimmune diseases, mental disorders, and beyond. In fact, there are very few chronic illnesses or diseases that do not respond favorably to our ancestral diet. has found wide acceptance not only with CrossFitters and athletes, but also with the medical and health professions, who have embraced it because of its wide-reaching therapeutic effects on metabolic syndrome diseases, autoimmune diseases, mental disorders, and beyond. In fact, there are very few chronic illnesses or diseases that do not respond favorably to our ancestral diet.

The novelty of The Paleo Diet The Paleo Diet is that a mortal human being like me didn't create it. Rather, I-along with many other scientists, physicians, and anthropologists worldwide-simply uncovered what was already there: the diet to which our species is genetically adapted. This is the diet of our hunter-gatherer ancestors, the foods consumed by every human being on the planet until a mere 333 human generations ago, or about ten thousand years ago. Our ancestors' diets were uncomplicated by agriculture, animal husbandry, technology, and processed foods. Then, as today, our health is optimized when we eat lean meats, seafood, and fresh fruits and veggies at the expense of grains, dairy, refined sugars, refined oils, and processed foods. is that a mortal human being like me didn't create it. Rather, I-along with many other scientists, physicians, and anthropologists worldwide-simply uncovered what was already there: the diet to which our species is genetically adapted. This is the diet of our hunter-gatherer ancestors, the foods consumed by every human being on the planet until a mere 333 human generations ago, or about ten thousand years ago. Our ancestors' diets were uncomplicated by agriculture, animal husbandry, technology, and processed foods. Then, as today, our health is optimized when we eat lean meats, seafood, and fresh fruits and veggies at the expense of grains, dairy, refined sugars, refined oils, and processed foods.

Nutritional science is not static. What we once believed to be true ten years ago is invariably replaced by fresh knowledge based on better experiments, more comprehensive data, and a newer understanding of how our bodies work. When I first wrote The Paleo Diet The Paleo Diet, a great deal of the dietary advice I offered was cutting edge-so much so, that it was looked on with skepticism by scientists and the public at large. Here's a perfect example. One 2002 online review of The Paleo Diet The Paleo Diet read, "Claims of improving diseases from diabetes to acne to polycystic ovary disease may be a little overstated." I feel vindicated knowing that the original dietary recommendations I made for type 2 diabetes, acne, and polycystic ovary syndrome have been confirmed by hundreds of scientific experiments. read, "Claims of improving diseases from diabetes to acne to polycystic ovary disease may be a little overstated." I feel vindicated knowing that the original dietary recommendations I made for type 2 diabetes, acne, and polycystic ovary syndrome have been confirmed by hundreds of scientific experiments.

Especially gratifying are a series of epidemiological experiments from Dr. Walter Willett and colleagues at the Harvard School of Public Health that linked milk consumption and the occurrence of acne. Even more convincing evidence for the diet-acne link comes from Dr. Neil Mann's research group at the Royal Melbourne Inst.i.tute of Technology, where acne patients were actually fed high-protein, low-glycemic-load diets and reported significant improvement in their symptoms.

Anytime a diet/health book survives eight years, the hindsight rule (hindsight is 20/20) surely has to come into play. Indeed it did with this book, as reflected by my current updates and edits to the original volume. The elegance of The Paleo Diet The Paleo Diet concept is that the essential idea (the evolutionary basis for optimal human nutrition) is fundamentally sound and will never change; as Boyd Eaton, the G.o.dfather of Paleolithic nutrition commented, "The science behind Paleolithic Nutrition is indisputable; however, we will continually hone the concept as newer information acc.u.mulates." concept is that the essential idea (the evolutionary basis for optimal human nutrition) is fundamentally sound and will never change; as Boyd Eaton, the G.o.dfather of Paleolithic nutrition commented, "The science behind Paleolithic Nutrition is indisputable; however, we will continually hone the concept as newer information acc.u.mulates."

So, what's new in this edition, and what are the noteworthy changes?

The first revision involves recommended oils. We are now down to only four: olive oil, flaxseed oil, walnut oil, and avocado oil. I no longer can recommend canola oil at all, and the only oil I believe should be used for cooking is olive oil. My friend and noted nutritionist Robert Crayhon always said to "let the data speak for itself," and I believe his words ring true. The rationale for these new recommendations is solely based on new facts that have emerged. You can find this updated information in this revised edition.

Another shift is that I have softened my stance on the saturated fat issue as more and more data become available, including information from my recent evolutionary paper on the topic.

Finally, as scientists begin to unravel the mystery of autoimmune diseases, it is becoming apparent that multiple nutritional elements of the Paleo Diet may protect us from these one hundred or more illnesses that afflict nearly 10 percent of the U.S. population.

All of this information, along with the tweaks needed to bring The Paleo Diet The Paleo Diet up to date in 2010, is to be found within this edition. I've also just published a new book, up to date in 2010, is to be found within this edition. I've also just published a new book, The Paleo Diet Cookbook The Paleo Diet Cookbook, which contains more than 150 Paleo recipes. I owe a debt of grat.i.tude to each and every Paleo Diet supporter for making this concept known to the world.

Acknowledgments.

I am the storyteller, but the tale I tell would not have been possible without the dedication and lifework of countless scientists from many diverse fields. I am particularly indebted to my friend and colleague S. Boyd Eaton for enlightening me with his seminal New England Journal of Medicine New England Journal of Medicine article "Paleolithic Nutrition" and then for generously recognizing me in the midst of a sea of faces. I have had countless hours of discussion (both on and off the electronic ether) regarding diet, disease, and anthropology with many notable scientists, physicians, and interested lay scholars. Without their encouragement, pa.s.sion, knowledge, and enthusiasm, I suspect that this book would not have been written. Thank you, Boyd Eaton, Jennie Brand Miller, Neil Mann, Andy Sinclair, Mike and Mary Dan Eades, Artemis Simopoulous, Bruce Watkins, Dean Esmay, Ward Nicholson, Don Wiss, Ben Balzer, Clark Spencer La.r.s.en, Mike Richards, John Speth, Norman Salem, Joe Hibbeln, Stephen Cunnane, Kim Hill, Craig Stanford, Robert Crayhon, Robert Gotshall, Joe Friel, Kevin Davy, Lynn Toohey, David Jenkins, David Lugwig, Soren Toubro, George Williams, Luisa Raijman, Michael Crawford, Staffan Lindeberg, Ray Audette, Wolfgang Lutz, Ann Magennis, Art DeVany, Ashton Embry, Bill DiVale, Pat Gray, Char-lie Robbins, Irvin Liener, Nicolai Worm, Tony Sebastian, Robert Heaney, Stewart Truswell, and Pam Keagy. Finally, many thanks to my agents, Carol Mann and Channa Taub, for working indefatigably to get this book off the ground, and to my editor, Tom Miller, for his commitment to and enthusiasm for the Paleo Diet as a book concept. article "Paleolithic Nutrition" and then for generously recognizing me in the midst of a sea of faces. I have had countless hours of discussion (both on and off the electronic ether) regarding diet, disease, and anthropology with many notable scientists, physicians, and interested lay scholars. Without their encouragement, pa.s.sion, knowledge, and enthusiasm, I suspect that this book would not have been written. Thank you, Boyd Eaton, Jennie Brand Miller, Neil Mann, Andy Sinclair, Mike and Mary Dan Eades, Artemis Simopoulous, Bruce Watkins, Dean Esmay, Ward Nicholson, Don Wiss, Ben Balzer, Clark Spencer La.r.s.en, Mike Richards, John Speth, Norman Salem, Joe Hibbeln, Stephen Cunnane, Kim Hill, Craig Stanford, Robert Crayhon, Robert Gotshall, Joe Friel, Kevin Davy, Lynn Toohey, David Jenkins, David Lugwig, Soren Toubro, George Williams, Luisa Raijman, Michael Crawford, Staffan Lindeberg, Ray Audette, Wolfgang Lutz, Ann Magennis, Art DeVany, Ashton Embry, Bill DiVale, Pat Gray, Char-lie Robbins, Irvin Liener, Nicolai Worm, Tony Sebastian, Robert Heaney, Stewart Truswell, and Pam Keagy. Finally, many thanks to my agents, Carol Mann and Channa Taub, for working indefatigably to get this book off the ground, and to my editor, Tom Miller, for his commitment to and enthusiasm for the Paleo Diet as a book concept.

PART ONE.

Understanding the Paleo Diet

Introduction.

This book represents the culmination of my lifelong interest in the link between diet and health, and of my fascination with anthropology and human origins. Although these scientific disciplines may at first appear to be unrelated, they are intimately connected. Our origins-the very beginnings of the human species-can be traced to pivotal changes in the diet of our early ancestors that made possible the evolution of our large, metabolically active brains. The Agricultural Revolution and the adoption of cereal grains as staple foods allowed us to abandon forever our previous hunter-gatherer lifestyle and caused the Earth's population to balloon and develop into the vast industrial-technological society in which we live today.

The problem, as you will see in this book, is that we are genetically adapted to eat what the hunter-gatherers ate. Many of our health problems today are the direct result of what we do-and do not-eat. This book will show you where we went wrong-how the standard American diet and even today's so-called healthy diets wreak havoc with our Paleolithic (Old Stone Age) const.i.tutions. It will also show you how you can lose weight and regain health and well-being by eating the way our hunter-gatherer ancestors ate-the diet that nature intended.

The reason for this book is very simple: the Paleo Diet is the one and only diet that ideally fits our genetic makeup. Just 333 generations ago-and for 2.5 million years before that-every human being on Earth ate this way. It is the diet to which all of us are ideally suited and the lifetime nutritional plan that will normalize your weight and improve your health. I didn't design this diet-nature did. This diet has been built into our genes.

More than twenty years ago, I read a book that endorsed vegetarian dieting t.i.tled Are You Confused? Are You Confused? I suspect that this t.i.tle pretty much sums up how many of us feel about the conflicting breakthroughs and mixed messages we hear every day from scientific and medical authorities on what we should and shouldn't eat to lose weight and be healthy. I suspect that this t.i.tle pretty much sums up how many of us feel about the conflicting breakthroughs and mixed messages we hear every day from scientific and medical authorities on what we should and shouldn't eat to lose weight and be healthy.

But here's the good news. Over the last twenty-five years, scientists and physicians worldwide have begun to agree on the fundamental principle underlying optimal nutrition-thanks in part to my colleague Dr. S. Boyd Eaton of Emory University in Atlanta. In 1985, Dr. Eaton published a revolutionary scientific paper called "Paleolithic Nutrition" in the prestigious New England Journal of Medicine New England Journal of Medicine suggesting that the ideal diet was to be found in the nutritional practices of our Stone Age ancestors. Although a few physicians, scientists, and anthropologists had been aware of this concept, it was Dr. Eaton's writings that brought this idea to center stage. suggesting that the ideal diet was to be found in the nutritional practices of our Stone Age ancestors. Although a few physicians, scientists, and anthropologists had been aware of this concept, it was Dr. Eaton's writings that brought this idea to center stage.

Dr. Eaton applied the most fundamental and pervasive idea of all biology and medicine-the theory of evolution by natural selection-to diet and health. His premise was simple: our genes determine our nutritional needs. And our genes were shaped by the selective pressures of our Paleolithic environment, including the foods our ancient ancestors ate.

Many modern foods are at odds with our genetic makeup-which, as we'll discuss in the book, is basically the same as that of our Paleolithic ancestors-and this is the cause of many of our modern diseases. By restoring the food types that we are genetically programmed to eat, we can not only lose weight, but also restore our health and well-being.

I have studied diet and health for the past three decades and have devoted the last twenty years to studying the Paleo Diet concept. I have been fortunate enough to work with Dr. Eaton to refine this groundbreaking idea and explore a wealth of new evidence. Together with many of the world's top nutritional scientists and anthropologists, I have been able to determine the dietary practices of our hunter-gatherer ancestors. Understanding what they ate is essential for understanding what we should eat today to improve our health and promote weight loss. Our research has been published in the top nutritional journals in the world.

It's all here for you in this book-all the dietary knowledge and wisdom that my research team and I have gleaned from our distant ancestors who lived in the days before agriculture. Part One explains what our Paleolithic ancestors ate, the basics of the Paleo Diet, and how civilization has made us stray from our original diet, bringing us ill health and obesity. Part Two shows how you can lose weight and how much you can lose, and also how the Paleo Diet can prevent and heal disease. Part Three spells out everything you need to know to follow the Paleo Diet-including meal plans for the three levels of the diet and more than 100 delicious Paleo recipes. That's the best part of the Paleo Diet-you'll eat well, feel great, and lose weight! The book ends with a complete list of scientific references that back up all of this information.

How Our Healthy Way of Life Went Wrong The Agricultural Revolution began 10,000 years ago-just a drop in the bucket compared to the 2.5 million years that human beings have lived on Earth. Until that time-just 333 generations ago-everyone on the planet ate lean meats, fresh fruits, and vegetables. For most of us, it's been fewer than 200 generations since our ancestors abandoned the old lifestyle and turned to agriculture. If you happen to be an Eskimo or a Native American, it's been barely four to six generations. Except for perhaps a half-dozen tiny tribes in South America and a few on the Andaman Islands in the Bay of Bengal, pure hunter-gatherers have vanished from the face of the Earth. When these few remaining tribes become Westernized during the next decade or so, this ancient way of life-which allowed our species to thrive, grow, and mature-will come to an end.

This loss of humanity's original way of life matters a great deal. Why? Look at us. We're a mess. We eat too much, we eat the wrong foods, and we're fat. Incredibly, more Americans are overweight than aren't: 68 percent of all American men over age twenty-five, and 64 percent of women over age twenty-five are either overweight or obese. And it's killing us. The leading cause of death in the United States-responsible for 35 percent of all deaths or 1 of every 2.8 deaths-is heart and blood vessel disease. Seventy-three million Americans have high blood pressure; 34 million have high cholesterol levels, and 17 million have type 2 diabetes. It's not a pretty picture.

Most people don't realize just how healthy our Paleolithic ancestors were. They were lean, fit, and generally free from heart disease and the other ailments that plague Western countries. Yet many people a.s.sume that Stone Age people had it rough, that their lives were "poor, nasty, brutish, and short," as Thomas Hobbes wrote in The Leviathan The Leviathan.

But the historical and anthropological record simply does not support this line of reasoning. Almost without exception, descriptions of hunter-gatherers by early European explorers and adventurers showed these people to be healthy, fit, strong, and vivacious. These same characteristics can be yours when you follow the dietary and exercise principles I have laid out in the Paleo Diet.

I have examined thousands of early-nineteenth and twentieth-century photographs of hunter-gatherers. They invariably show indigenous people to be lean, muscular, and fit. The few medical studies of hunter-gatherers who managed to survive into the twentieth century also confirm earlier written accounts by explorers and frontiersmen. No matter where they lived-in the polar regions of Canada, the deserts of Australia, or the rain forests of Brazil-the medical records were identical. These people were free from signs and symptoms of the chronic diseases that currently plague us. And they were lean and physically fit. The medical evidence shows that their body fat, aerobic fitness, blood cholesterol, blood pressure, and insulin metabolism were always superior to those of the average modern couch potato. In most cases, these values were equivalent to those of modern-day, healthy, trained athletes.

High blood pressure (hypertension) is the most prevalent risk factor for heart disease in the United States. It's almost unheard of in indigenous populations. The Yanomamo Indians of northern Brazil and southern Venezuela, to whom salt was unknown in the late 1960s and early 1970s, were absolutely free from hypertension. Their blood pressure didn't increase with age and remained remarkably low by today's standards. Amazingly, scientific studies of Greenland Eskimos by Drs. Hans Bang and Jrn Dyerberg from Aalborg Hospital in Aalborg, Denmark, showed that despite a diet containing more than 60 percent animal food, not one death from heart disease-or even a single heart attack-occurred in 2,600 Eskimos from 1968 to 1978. This death rate from heart disease is one of the lowest ever reported in the medical literature. For a similar group of 2,600 people in the United States during a ten-year period, the expected number of deaths from heart disease would be about twenty-five.

When you put into practice the nutritional guidelines of the Paleo Diet, you will be getting the same protection from heart disease that the Eskimos had. You will also become lean and fit, like your ancient ancestors. This is your birthright. By going backward in time with your diet, you will actually be moving forward. You'll be combining the ancient dietary wisdom with all of the health advantages that modern medicine has to offer. You will reap the best of both worlds.

1.

Not Just Another Low-Carb Diet.

What's the diet craze this week? You name it, there's a book selling it-and people buying it, hoping for a "magic bullet" to help them shed excess pounds. But how can everybody be right? More to the point, is anybody anybody right? What are we supposed to eat? How can we lose weight, keep it off-and not feel hungry all the time? What's the best diet for our health and well-being? right? What are we supposed to eat? How can we lose weight, keep it off-and not feel hungry all the time? What's the best diet for our health and well-being?

For more than thirty years, as an avid researcher of health, nutrition, and fitness, I have been working to answer these questions. I started this quest because I wanted to get past all the hype, confusion, and political posturing swirling around dietary opinion. I was looking for facts: the simple, unadulterated truth. The answer, I found, was hidden back in time-way back, with ancient humans who survived by hunting wild animals and fish and gathering wild fruits and vegetables. These people were known as "hunter-gatherers," and my research team and I published our a.n.a.lysis of what many of them (more than 200 separate societies) ate in The American Journal of Clinical Nutrition. The American Journal of Clinical Nutrition. We were astonished at the diversity of their diet. We were also amazed at what they did We were astonished at the diversity of their diet. We were also amazed at what they did not not eat-which we'll get to in a minute and which may surprise you. eat-which we'll get to in a minute and which may surprise you.

Health Secrets of Our Ancestors What do Paleolithic people have to do with us? Actually, quite a lot: DNA evidence shows that basic human physiology has changed little in 40,000 years. Literally, we are Stone Agers living in the s.p.a.ce Age; our dietary needs are the same as theirs. Our genes are well adapted to a world in which all the food eaten daily had to be hunted, fished, or gathered from the natural environment-a world that no longer exists. Nature determined what our bodies needed thousands of years before civilization developed, before people started farming and raising domesticated livestock.

In other words, built into our genes is a blueprint for optimal nutrition-a plan that spells out the foods that make us healthy, lean, and fit. Whether you believe the architect of that blueprint is G.o.d, or G.o.d acting through evolution by natural selection, or by evolution alone, the end result is still the same: We need to give our bodies the foods we were originally designed to eat.

Your car is designed to run on gasoline. When you put diesel fuel into its tank, the results are disastrous for the engine. The same principle is true for us: We are designed to run best on the wild plant and animal foods that all human beings gathered and hunted just 333 generations ago. The staples of today's diet-cereals, dairy products, refined sugars, fatty meats, and salted, processed foods-are like diesel fuel to our bodies' metabolic machinery. These foods clog our engines, make us fat, and cause disease and ill health.

Sadly, with all of our progress, we have strayed from the path designed for us by nature. For instance: * Paleolithic people ate no dairy food. Imagine how difficult it would be to milk a wild animal, even if you could somehow manage to catch one.* Paleolithic people hardly ever ate cereal grains. This sounds shocking to us today, but for most ancient people, grains were considered starvation food at best.* Paleolithic people didn't salt their food.* The only refined sugar Paleolithic people ate was honey, when they were lucky enough to find it.* Wild, lean animal foods dominated Paleolithic diets, so their protein intake was quite high by modern standards, while their carbohydrate consumption was much lower.* Virtually all of the carbohydrates Paleolithic people ate came from nonstarchy wild fruits and vegetables. Consequently, their carbohydrate intake was much lower and their fiber intake much higher than those obtained by eating the typical modern diet. * The main fats in the Paleolithic diets were healthful, monounsaturated, polyunsaturated, and omega 3 fats-not the trans fats and certain saturated fats that dominate modern diets. * The main fats in the Paleolithic diets were healthful, monounsaturated, polyunsaturated, and omega 3 fats-not the trans fats and certain saturated fats that dominate modern diets.

With this book, we are returning to the diet we were genetically programmed to follow. The Paleo Diet is more than a blast from the past. It's the key to speedy weight loss, effective weight control, and, above all, lifelong health. speedy weight loss, effective weight control, and, above all, lifelong health. The Paleo Diet enlists the body's own mechanisms, evolved over millions of years, to put the brakes on weight gain and the development of the chronic diseases of civilization. It is the closest approximation we can make, given the current scientific knowledge, to humanity's original, universal diet-the easy-to-follow, cravings-checking, satisfying program that nature itself has devised. The Paleo Diet enlists the body's own mechanisms, evolved over millions of years, to put the brakes on weight gain and the development of the chronic diseases of civilization. It is the closest approximation we can make, given the current scientific knowledge, to humanity's original, universal diet-the easy-to-follow, cravings-checking, satisfying program that nature itself has devised.

The Problems with Most Low-Carb Diets The Paleo Diet is a low-carbohydrate diet-but that's where any resemblance to the glut of low-carbohydrate fad diets ends. Remember, the Paleo Diet is the only diet based on millions of years of nutritional facts-the one ideally suited to our biological needs and makeup and the one that most closely resembles hunter-gatherer diets. How does the Paleo Diet compare with the low-carb fad diets and the average U.S. diet?

[image]

Modern low-carbohydrate weight-loss diets are really high-fat diets that contain moderate levels of protein. They don't have the high levels of protein that our ancestors ate-the levels found in the Paleo Diet. Actually, compared with what our ancestors ate, the carbohydrate content of these modern weight-loss diets is far too low. Even worse, almost all of these low-carbohydrate diets permit unlimited consumption of fatty, salty processed meats (such as bacon, sausage, hot dogs, and lunch meats) and dairy products (cheeses, cream, and b.u.t.ter) while restricting the consumption of fruits and vegetables. Cancer-fighting fruits and vegetables! This dietary pattern is drastically different from that of our ancestors.

And although low-carbohydrate diets may be successful in promoting weight loss, many dieters are achieving short-term weight loss at the expense of long-term health and well-being. Here's what the sellers of these diet plans don't want you to know: when low-carbohydrate diets cause weight loss in the short term, it's because they deplete the body's reserves of muscle and liver glycogen (carbohydrate), and the weight you're losing rapidly is mostly water weight.

When low-carbohydrate diets cause weight loss in the long run (weeks or months), it's because more calories are being burned than consumed, plain and simple. Low-carbohydrate diets tend to normalize insulin metabolism in many people, particularly in those who are seriously overweight. This normalization prevents swings in blood sugar that, in turn, may cause some people to eat less and lose weight. It is the cutback in total calories that lowers total cholesterol and low-density lipoprotein (LDL) cholesterol (the bad cholesterol) levels. Also, reductions in dietary carbohydrates (whether calories are cut or not) almost always cause a decline in blood triglycerides and an increase in blood high-density lipoprotein (HDL) cholesterol (the good cholesterol).

So, if low-carbohydrate diets cause someone to consume fewer calories, they may help produce weight loss and improvements in blood chemistry, at least over the short haul. However, dieters beware: when low-carbohydrate, high-fat diets are followed without without a decrease in the daily consumption of calories, they are, according to the American Dietetic a.s.sociation, "a nightmare." Let's see why. a decrease in the daily consumption of calories, they are, according to the American Dietetic a.s.sociation, "a nightmare." Let's see why.

Low Carb Doesn't Mean Low Cholesterol Despite what anybody tells you-despite the outrageous claims of the low-carbohydrate, high-fat diet doctors-if you eat a lot of the saturated fats found in cheeses, b.u.t.ter, and bacon and don't cut your overall calorie intake, your cholesterol will go up. The medical community has known this for more than fifty years. It's been demonstrated in metabolic ward studies, in which people are locked into a hospital wing and only allowed to eat foods that have been carefully weighed and a.n.a.lyzed. Many of the low-carbohydrate diet doctors claim that these clinical trials are invalid because none of them reduced the carbohydrate content sufficiently. These doctors should know better; low carbohydrates don't guarantee low cholesterol.

Dr. Stephen Phinney and colleagues from the Ma.s.sachusetts Inst.i.tute of Technology conducted a normal caloric intake metabolic ward trial involving nine healthy, lean men. These men consumed nothing but meat, fish, eggs, cheese, and cream for thirty-five days. They had a low carbohydrate intake-less than 20 grams a day-but it didn't matter. Their blood cholesterol levels still went up, from 159 to 208 on average in just thirty-five days. This study indicates that diets high in a specific saturated fat called palmitic acid tends to raise blood cholesterol levels when caloric intake levels are normal.

So, at best, low-carbohydrate, high-fat diets are a temporary fix. At worst, they can cause big trouble in the long run by elevating LDL cholesterol levels, which increases the risk for heart and cardiovascular disease.

Healthy Fats, Not Lethal Fats One major difference between the Paleo Diet and the low-carbohydrate, high-fat diets we just talked about is the fats. In most modern low-carbohydrate weight-loss diets, no distinction is made between good fats and bad fats. All fats are generally lumped together; the goal is simply to reduce carbohydrates and not worry about fats.

But you should should worry about fats. Not all fats are created equal, and the impact of fat on blood cholesterol-and the odds of developing heart disease-can't be ignored. The problem is, fats are confusing for many people trying to make good dietary decisions. For one thing, many of them sound alike. How are saturated fats different from monounsaturated-or even polyunsaturated-fats? How are omega 6 fats different from the omega 3 variety? worry about fats. Not all fats are created equal, and the impact of fat on blood cholesterol-and the odds of developing heart disease-can't be ignored. The problem is, fats are confusing for many people trying to make good dietary decisions. For one thing, many of them sound alike. How are saturated fats different from monounsaturated-or even polyunsaturated-fats? How are omega 6 fats different from the omega 3 variety?

* Monounsaturated fats are good. They're found in olive oil, nuts, and avocados; are known to lower blood cholesterol; and help prevent artery clogging or atherosclerosis.* Saturated fats are mostly bad. They're found in processed meats, whole dairy products, and many bakery items; most of them are known to raise cholesterol. A key exception is a saturated fat called stearic acid, which, like monounsaturated fats, lowers blood cholesterol levels.* Polyunsaturated fats are a mixed bag-some are more beneficial than others. For example, omega 3 polyunsaturated fats (the kind found in fish oils) are healthy fats, which can improve blood chemistry and reduce your risk of many chronic diseases. But omega 6 polyunsaturated fats (found in vegetable oils, many baked goods, and snack foods) are not good when you eat too much of them at the expense of omega 3 fats.

People in the Paleolithic Age ate a lot of monounsaturated fats; they had saturated and polyunsaturated fats in moderation-but when they did have polyunsaturated fats, they had a proper balance of the omega 3 and omega 6 fats. They consumed far fewer omega 6 polyunsaturated fats than we do today. In addition, the main saturated fat in wild animals was healthful stearic acid, not the cholesterol-raising palmitic acid, which dominates the fat of feedlot cattle.

How important are fats in the diet? Here's a modern example: People who live in Mediterranean countries, who consume lots of olive oil, are much less likely to die of heart disease than Americans or northern Europeans, who don't consume as much olive oil. Instead, our Western diet is burdened by high levels of certain saturated fats, omega 6 fats, and trans fats and sadly lacking in heart-healthy, artery-protecting omega 3 fats.

Our studies of hunter-gatherers suggest that they had low blood cholesterol and relatively little heart disease. Our research team believes that dietary fats were a major reason for their freedom from heart disease.

Saturated Fats, Reconsidered In the first edition of The Paleo Diet The Paleo Diet, I was adamant that you should avoid fatty processed meats such as bacon, hot dogs, lunch meats, salami, bologna, and sausages because they contain excessive saturated fats, which raise your blood cholesterol levels. That message still holds true today, but new information subtly alters this fundamental point of Paleo Dieting, and, as always, the devil lies in the details. Should you now go out and eat bacon and processed meats to your heart's desire? Absolutely not! Processed meats are synthetic mixtures of meat (muscle) and fat combined artificially at the meatpacker's or butcher's whim, with no regard for the true fatty acid profile of wild animal carca.s.ses that our hunter-gatherer ancestors ate. In addition to their unnatural fatty acid profiles (high in omega 6 fatty acids, low in omega 3 fatty acids, and high in saturated fatty acids), processed fatty meats are full of preservatives such as nitrites, which are converted into potent cancer-causing nitrosamines in our guts. To make a bad situation worse, these unnatural meats are typically full of salt, high-fructose corn syrup, wheat, grains, and other additives that have multiple adverse health effects.

So, artificially produced, synthetic, factory meats have little or nothing to do with the wild animal foods our hunter-gatherer ancestors ate, and they should be avoided. But how about the unprocessed fatty meats that we routinely eat, day in and day out, that are produced in feedlots and butchered without adding fats or preservatives? These are meats such as T-bone steaks, spareribs, lamb chops, and chicken legs and thighs, as well as fatty cuts of pork and other fatty domestic meats. Are they a problem?

I realize that many, perhaps most, readers are not hunters and have never seen carca.s.ses of wild animals, such as deer, elk, or antelope. Nor have you had the opportunity to visually contrast the carca.s.ses of feedlot-produced animals to wild animals. I can tell you that there is no comparison. My research group and I have taken the time to do the chemical a.n.a.lyses between wild and feedlot-produced animals, and we have published our results in some of the top nutritional journals in the world.

Wild animal carca.s.ses are lean, have little external fat, and exhibit virtually no fat between the muscles (marbling). In contrast, feedlot-produced cattle maintain a four- to six-inch layer of white fat covering the animal's entire body. These artificial products of modern agriculture are overweight, obese, and sick. Their muscles are infiltrated with that fat that we call marbling, a trait that improves flavor but makes the cattle insulin resistant and in poor health, just like us. Wild animals rarely or never exhibit marbling.

Because feedlot-raised animals are exclusively fed grains (corn and sorghum) in the last half of their lives, their meat has high concentrations of omega 6 fatty acids at the expense of health-promoting omega 3 fatty acids. The meat of grain-fed livestock is vastly at odds with that of wild animals. Check out Appendix B in this book. A 100 gram (~ 4 lb.) serving of T-bone beefsteak gives you a walloping 9.1 grams of saturated fat, whereas a comparable piece of bison roast yields only 0.9 grams of saturated fat. You would have to eat ten times more bison meat to get a similar amount of saturated fat than the amount in a single serving of T-bone steak.

It would be difficult for our hunter-gatherer ancestors to eat anywhere near the amount of saturated fat that we get on a yearly basis in the typical Western diet. So, does dietary saturated fat promote heart disease? Should Paleo Dieters try to limit the fatty domesticated meats in their diet in order to reduce saturated fat? This question is not as clear-cut as it seemed twenty-five years ago, when Drs. Michael Brown and Joseph Goldstein of the University of Texas Southwest Medical Center were awarded the n.o.bel Prize in medicine for discovering that saturated fats down-regulated the LDL receptor. Their discovery and subsequent randomized, controlled human trials have unequivocally shown that certain saturated fats (lauric acid [12:0], myristic acid [14:0], and palmitic acid, [16:0]) but not all (stearic acid [18:0]), elevate blood cholesterol levels in humans, all other factors being equal. These facts are undeniable. Yet the next question is contentious and has divided the nutritional and medical community in recent years: do increased blood cholesterol levels necessarily predispose all people to an increased risk for cardiovascular disease?

As the scientific community has struggled with this question during the last few years, we should remember that the evolutionary template will almost always guide us to the correct answer. The clogging of arteries that eventually results in fatal heart attacks comes about through a process called atherosclerosis, in which plaque (cholesterol and calcium) builds up in the arteries that supply the heart itself with blood. It was originally thought that this buildup gradually narrowed and finally closed the arteries supplying the heart, thereby causing a heart attack. We now know that this model is inaccurate and too simple.

In the last ten to fifteen years, it has become apparent that inflammation is involved at every step of the way when arteries become clogged with plaque. In fact, the fatal event causing a heart attack is not the gradual narrowing of arteries supplying the heart but rather the rupturing of the fibrous cap that surrounds and walls off plaque that forms in the heart's arteries. Chronic low-level inflammation triggers the fibrous cap to rupture, which in turn causes a clot to form in the arteries that supply the heart, resulting in a heart attack. Without chronic low-level inflammation, heart attacks probably would rarely or never occur.

So, do dietary saturated fats from fatty meats cause the artery-clogging process known as atherosclerosis? If we look at the evolutionary evidence, the answer is a resounding yes. Dr. Michael Zimmerman, a pathologist at Hahnemann University in Pennsylvania, had the rare opportunity to perform autopsies on a number of Eskimo mummies that had been frozen in Alaska's permafrost for hundreds of years. The first mummy was that of a fifty-three-year-old woman whose body washed out of the frozen banks of Saint Lawrence Island in October 1972. Radiocarbon dating indicated that she had died in 400 A.D. from a landslide that had completely buried her. Dr. Zimmerman's autopsy revealed moderate atherosclerosis in the arteries supplying her heart but no evidence of a heart attack. The second frozen mummy was also a female, forty to forty-five years of age, who had also been engulfed in an ice-and-mud-slide in 1520 A.D. near Barrow, Alaska. Similarly, the autopsy showed atherosclerotic plaques lining the arteries of her heart.

From my prior studies of worldwide hunter-gatherers, we know that these Eskimo women had a diet that consisted almost entirely (97 percent) of wild animal foods, including whales, walruses, seals, salmon, muskoxen, and caribou. Because they lived so far north (63 to 71 degrees north lat.i.tude), plant foods simply were unavailable; consequently, their carbohydrate intake was virtually zero. Yet they still developed atherosclerosis. Perhaps Drs. Brown and Goldstein were right, after all: high dietary intakes of saturated fats do promote atherosclerosis. Despite these facts, the best archaeological and medical evidence shows that Eskimos living and eating in their traditional ways rarely or never died from heart attacks or strokes.

So, now we have the facts we need to come to closure with the saturated fat-heart disease issue. Dietary saturated fats from excessive consumption of processed fatty meats and feedlot-produced meats increase our blood cholesterol concentrations, but unless our immune systems are chronically inflamed, atherosclerosis likely will not kill us from either heart attacks or strokes.

The new advice I can give you is this: If you are faithful to the basic principles of the Paleo Diet, consumption of fatty meats will probably have a minimal outcome on your health and wellbeing-as it did for our hunter-gatherer ancestors. Consumption of fatty meats and organs had survival value in an earlier time when humans didn't eat grains, legumes, dairy products, refined sugars, and salty processed foods, the foods that produce chronic low-level inflammation in our bodies through a variety of physiological mechanisms. I will explain this in more depth in my next book, Living the Paleo Diet Living the Paleo Diet.

Disease-Fighting Fruits and Vegetables A big problem with low-carbohydrate weight-loss diets is what they do to health-promoting fruits and vegetables-they nearly eliminate them. Because of a technicality-a blanket restriction on all types of carbohydrates, even beneficial ones, to between 30 and 100 grams per day-fruits and veggies are largely off-limits. This is a mistake. Fruits and vegetables-with their antioxidants, phytochemicals, and fiber-are some of our most powerful allies in the war against heart disease, cancer, and osteoporosis. Yet just one papaya (59 grams of carbohydrate) would blow the daily limit for two of the most popular low-carbohydrate diets. Eating an orange, an apple, and a cup of broccoli and carrots (73 grams of carbohydrate) -just a drop in the bucket to hunter-gatherers, whose diets were rich in fruits and vegetables-would wreck all but the most liberal low-carbohydrate diets.

Humanity's original carbohydrate sources-the foods we survived on for millions of years-didn't come from starchy grains and potatoes, which have high glycemic indices that can rapidly cause blood sugar to spike. Instead, they came from wild fruits and vegetables with low glycemic indices that produced minimal, gradual gradual rises in blood sugar. These are the carbohydrates that you'll be eating on the Paleo Diet. These nonstarchy carbohydrates normalize your blood glucose and insulin levels, promote weight loss, and make you feel energized all day long. rises in blood sugar. These are the carbohydrates that you'll be eating on the Paleo Diet. These nonstarchy carbohydrates normalize your blood glucose and insulin levels, promote weight loss, and make you feel energized all day long.

The Osteoporosis Connection One of the greatest-and least recognized-benefits of fruits and vegetables is their ability to slow or prevent the loss of bone density, called "osteoporosis," that so often comes with aging. As far back as 1999, Dr. Katherine Tucker and colleagues at Tufts University examined the bone mineral status of a large group of elderly men and women. These scientists found that the people who ate the most fruits and vegetables had the greatest bone mineral densities and the strongest bones. In the ensuing ten years, more than 100 scientific studies have confirmed this concept.

But what about calcium? Surely, eating a lot of cheese can help prevent osteoporosis? The answer is a bit more complicated. One of the great ironies of the low-carbohydrate, high-fat diets is that even though they allow unlimited consumption of high-calcium cheeses, they almost certainly will be found to promote bone loss and osteoporosis in the long run. How can this be? Because getting a lot of dietary calcium from cheese, by itself, isn't enough to offset the lack of fruits and vegetables.

Nutrition scientists use the term "calcium balance" to describe this process. It's the difference between how much calcium you take in and how much you excrete. Most of us have gotten the message about consuming calcium. But the other part of the equation-how much calcium you excrete-is just as important. It is quite possible for you to be in calcium balance on a low calcium intake if your calcium excretion is also low. On the other hand, it's easy for you to fall out of calcium balance-even if you load up on cheese at every meal-if you lose more calcium than you take in.

The main factor that determines calcium loss is yet another kind of balance-the acid-base balance. acid-base balance. If your diet has high levels of acid, you'll lose more calcium in your urine; if you eat more alkaline foods, you'll retain more calcium. A study in the If your diet has high levels of acid, you'll lose more calcium in your urine; if you eat more alkaline foods, you'll retain more calcium. A study in the New England Journal of Medicine New England Journal of Medicine by my colleague Dr. Anthony Sebastian and his research group at the University of California at San Francisco showed that simply taking pota.s.sium bicarbonate (an alkaline base) neutralized the body's internal acid production, reduced urinary calcium losses, and increased the rate of bone formation. In a follow-up report in the by my colleague Dr. Anthony Sebastian and his research group at the University of California at San Francisco showed that simply taking pota.s.sium bicarbonate (an alkaline base) neutralized the body's internal acid production, reduced urinary calcium losses, and increased the rate of bone formation. In a follow-up report in the New England Journal of Medicine, New England Journal of Medicine, Dr. Lawrence Appel at Johns Hopkins University reported that diets rich in fruits and vegetables (these are alkaline foods) significantly reduced urinary calcium loss in 459 men and women. Dr. Lawrence Appel at Johns Hopkins University reported that diets rich in fruits and vegetables (these are alkaline foods) significantly reduced urinary calcium loss in 459 men and women.

See Appendix A for a list of common foods and their acid-base values.