The Paleo Diet (8 page)

The key to the Paleo Diet is to stay with this wonderful way of eating. I can guarantee that you will immediately feel better. Your energy level will increase; you won’t have to endure that late-afternoon tiredness or “blah” feeling. In the morning, you’ll wake up charged and ready to greet the new day. You’ll feel better with each passing day, and as the weeks go by, you’ll notice that your clothes feel a bit loose. Your weight will gradually drop—week by week—until your normal, healthy body weight is restored. For some people, this may only take one or two months; for others, six months to a year; and for those with severe weight and health problems, a year or more. But the bottom line is that
it will happen.

Many people also experience clearing of their sinuses, less stiffness of their joints in the morning, and normalization of bowel function. Indigestion, heartburn, and acid stomach are reduced and may even vanish completely within a few weeks of adopting this diet.

People with high cholesterol and abnormal blood chemistry can expect to see improvements within two weeks of starting the diet. Blood triglyceride levels will drop within days, and the good HDL cholesterol will rise rapidly as well. In addition, for most people on the Paleo Diet, total blood cholesterol and LDL cholesterol drop within the first two weeks.

The Paleo Diet is particularly helpful for people with type 2 diabetes, cardiovascular disease, high blood pressure, kidney stones, asthma, acne, and osteoporosis. There is also a significant body of evidence suggesting that the Paleo Diet may be helpful in certain autoimmune diseases such as celiac disease, dermatitis herpetiformis, rheumatoid arthritis, multiple sclerosis, and Sjögren’s syndrome. It even reduces your risk of many types of cancer.

So eat well, lose weight, and be healthy with the Paleo Diet.

The blink of an eye. That’s how long, in the grand scheme of human history, we have grown food and domesticated livestock. It’s been only 333 generations since this change—known as the “Agricultural Revolution”—happened, and yet we have almost completely lost track of the foods our ancient ancestors ate. The so-called new foods that agriculture gave us so completely displaced the old foods that most of us are unaware that these foods were ever new. Many people assume that cereals, dairy products, salted foods, legumes, domesticated meats, and refined sugars have always been part of our diet. Not true! We need to rediscover the foods that brought our Paleolithic ancestors vibrant health, lean bodies, and freedom from chronic disease. The foods that agreed nicely with their genetic blueprints are the same foods that agree nicely with our genetic blueprints.

But what are these foods? How can we possibly know what our Paleolithic ancestors ate? My research team and I have been asking these same questions for the past decade. I am happy to tell you that we have found answers to these questions by carefully piecing together information from four sources:

The Paleolithic (Old Stone Age) era began some 2.5 million years ago in Africa when the first crude stone tools were developed. It ended about 10,000 years ago in the Middle East, with the first ancient farms. (Perhaps twenty different species of ancient humans lived in the Paleolithic era. However, for the purposes of this book, we’ll cover only the diets of our direct ancestors.) We can trace the evidence showing the dominance of lean meat in human diets from our origins 2.5 million years ago until the beginnings of agriculture 10,000 years ago.

The notion that human beings were meant to be vegetarians runs contrary to every shred of evolutionary evidence from the fossil and anthropological record. We owe a huge debt to lean meat. In fact, scientific evidence overwhelmingly suggests that if our ancient ancestors had eaten a meatless diet, we wouldn’t be where we are today. I wouldn’t have become a scientist, you wouldn’t be reading this book, and we would all look a lot more like our nearest animal relative—the chimpanzee.

How can this be? Chimps are hairy, and they have a big gut. They swing from trees. Well, yes, but about 5 to 7 million years ago, so did our prehuman ancestors. The evidence is that the family tree forks—and humans moved into a category all their own. But genetically speaking, we are only about 1.7 percent different from the chimp.

Chimps are mostly vegetarians (although they do eat a few insects, bird eggs, and the occasional small animal), and they have the big, protruding belly characteristic of vegetarian animals (horses and cows, for example, have big bellies, too). Apes need large, active guts to extract the nutrients from their fiber-filled, plant-based diet.

About 2.5 million years ago, our ancestors began trading in their big guts for bigger brains—to the point where today our bellies are about 40 percent smaller than those of chimps and our brains are about three times larger. The turning point came when our ancestors figured out that eating animal food (meat and organs) gave them much more energy. Over the years, their bellies began to shrink—because they didn’t need the extra room to process all that roughage. All the energy formerly needed by the gut was diverted to the brain, which doubled and then tripled in size. Without nutrient-dense animal foods in the diet, the large brains that make us human never would have had the chance to develop. Meat and animal foods literally shaped our genome.

Interestingly, just before the same period when human brains began to expand, something new came on the scene: tools—crude stone weapons, and knives that our ancestors used to butcher animal carcasses and later to hunt. We know this because of telltale cut marks that have been found on the bones of fossilized animals and from evidence (a classic example is the 125,000-year-old spear crafted from a yew tree found embedded between the ribs of an extinct straight-tusked elephant in Germany) compiled at thousands of archaeological sites worldwide.

At first, humans were not terribly good hunters. They started out as scavengers who trailed behind predators such as lions and ate the leftovers remaining on abandoned carcasses. The pickings were slim; ravenous lions don’t leave much behind, except for bones. But with their handy tools (stone anvils and hammers), our early ancestors could crack the skulls and bones and still find something to eat—brains and fatty marrow.

Marrow fat was the main concentrated energy source that enabled the early human gut to shrink, while the scavenged brains contained a specific type of omega 3 fat called “docosahexaenoic acid” (DHA), which allowed the brain to expand. Docosahexaenoic acid is the building block of our brain tissue.

Without a dietary source of DHA, the huge expansion of our brain capacity could never have happened. Without meat, marrow, and brains, our human ancestors never would have been able to walk out of tropical Africa and colonize the colder areas of the world. If these people had depended on finding plant foods in cold Europe, they would have starved. In a landmark series of studies, my colleague Mike Richards, at Oxford University, studied the bones of Paleolithic people who lived in England some 12,000 years ago. Their diet, Richards confirmed, was almost identical to that of top-level carnivores, such as wolves and bears.

Why would any sane person get close enough to poke a spear into a sharp-hoofed, kicking, and snorting 600-pound horse—much less a raging 5-ton mammoth? Why didn’t Paleolithic people play it safe, gathering berries and nuts and snaring rabbits, rodents, and small birds? Again, the wisdom of the old ways becomes clear.

The basic idea of foraging for food—whether you’re a human, a wolf, or even a house cat chasing a mouse—is simple. You’ve got to receive more energy from the food you capture than you use in trying to capture it. If you run around all day and use up 1,000 calories, but come home with only ten apples worth a grand total of 800 calories, you’re going to be very hungry. So when Paleolithic people went looking for food, they tried to get the most bang for the buck. The best way to do this, they found, was with a large animal. It takes a lot more energy to run down and capture 1,600 one-ounce mice than it does to kill a single deer weighing 100 pounds (1,600 ounces). But there’s a much more important reason why larger animals were preferred. It’s called “protein toxicity.”

We can only tolerate a certain amount of protein at a time- about 200 to 300 grams a day. Too much protein makes us nauseated, causes diarrhea, and eventually can kill us. This is why our Paleolithic ancestors couldn’t just eat lean muscle meat. They needed to eat fat along with the lean meat, or they needed to supplement the lean meat with carbohydrates from plant foods. Early explorers and frontiersmen in North America knew this, too. They were painfully aware of the toxic effect of too much lean protein; they called the illness “rabbit starvation.”

On average, large animals like deer and cows (or, for Paleolithic people, mammoths and wild horses) contain more fat and less protein than smaller animals like rabbits and squirrels. The squirrel’s body is 83 percent protein and 17 percent fat; the mule deer’s body is 40 percent protein and 60 percent fat. If you ate nothing but squirrel, you would rapidly exceed the body’s protein ceiling, and like those early pioneers, you’d end up with rabbit starvation. On the other hand, if you only had deer to eat, you’d be doing fine. You would not develop protein toxicity because you’d be protected by the deer’s higher fat content. This is why Paleolithic hunters risked their lives hunting larger animals.

In the Paleo Diet, you’re protected from protein toxicity, too—by unlimited access to fresh fruits and vegetables. You’re also protected by the good cholesterol-lowering monounsaturated fats and by our most powerful deterrent to heart disease—omega 3 fatty acids. With these safeguards in place, protein is your friend. High levels of protein speed up your metabolism, reduce your appetite, and lower your cholesterol. You will benefit from eating lean protein at every meal. I can assure you that as long as you eat plenty of fresh fruits and vegetables, there is no such thing as too much protein.

My research team and I have found that, ideally, a little more than half—55 percent—of your calories should come from lean meats, organ meats, fish, and seafood. The balance should come from fresh fruits and vegetables, some nuts, and healthful oils.

In the average American diet, not only is the balance of plant to animal food off-kilter, it’s almost exactly the opposite of what we are genetically programmed to eat. In the typical American diet, 24 percent of the calories come from cereals, 11 percent from dairy products, 18 percent from refined sugars, and 18 percent from refined oils. These foods represent 71 percent of the energy consumed in the typical American diet—yet virtually none of them are to be found on the Paleo menu of lean meats, fresh fruits, and vegetables. In the American diet, about 38 percent of the calories come from animal foods, most of them high-fat and unhealthy meats (hot dogs, fatty ground beef, bacon, lunch meats, etc.)—a far cry from the Paleo Diet.

The Agricultural Revolution changed the world and allowed civilization—cities, culture, technological and medical achievements, and scientific knowledge—to develop. These were all good things. And yet, there was a huge downside. The Agricultural Revolution is also responsible for much of today’s obesity and chronic disease. The foods that agriculture brought us—cereals, dairy products, fatty meats, salted foods, and refined sugars and oils—proved disastrous for our Paleolithic bodies.

Nobody could have anticipated this revolution or its consequences. The early farmers didn’t have some great plan to overthrow the old system. They were just looking for better ways to feed their families in the face of a rising population and dwindling food resources. It all started in the Middle East about 10,000 years ago, when some enterprising people started to sow and harvest wild wheat seeds. Later, they domesticated barley and a few legumes and then livestock—sheep, goats, and pigs. They still picked wild fruits and vegetables and still hunted wild game, but the die was cast; the diet had changed dramatically.

The archaeological record clearly shows that whenever and wherever ancient humans sowed seeds (and replaced the old animal-dominated diets), part of the harvest included health problems. One physical ramification of the new diet was immediately obvious: early farmers were markedly shorter than their ancestors. In Turkey and Greece, for example, preagricultural men stood 5 feet 9 inches tall and women 5 feet 5 inches. By 3000 B.C., the average man had shrunk to 5 feet 3 inches and the average woman to 5 feet. But getting shorter—not in itself a health problem—was the least of the changes in these early farmers. Studies of their bones and teeth have revealed that these people were basically a mess: they had more infectious diseases than their ancestors, more childhood mortality, and shorter life spans in general. They also had more osteoporosis, rickets, and other bone mineral disorders, thanks to the cereal-based diets. For the first time, humans were plagued with vitamin- and mineral-deficiency diseases—scurvy, beriberi, pellagra, vitamin A and zinc deficiencies, and iron-deficiency anemia. Instead of the well-formed, strong teeth their ancestors had, there were now cavities. Their jaws, which were formerly square and roomy, were suddenly too small for their teeth, which overlapped each other.

What had gone wrong? How could the benign practice of agriculture—harnessing nature’s bounty—have caused so many health problems? We now know that although the population was soaring, the quality of life—as well as the average life span—was in a nosedive. The new staples, cereals and starches, provided calories but not the vital nutrients of the old diet—lean meats, fruits, and vegetables. The result—ill health and disease.