The Paleo Diet

by Cordain, Loren

  A lean and healthy body is your birthright. The Paleo Diet is not a quick-fix solution. It is not a temporary, gimmicky diet. It’s a way of eating that will gradually normalize your body weight to its ideal level and keep the pounds off permanently.

  There’s one very simple concept that you must understand when it comes to losing weight—the First Law of Thermodynamics, which states that energy is neither created nor destroyed. This means that the energy—calories—you put into your body must equal the energy you expend. Otherwise, you’ll either gain or lose weight. If you eat more calories than you burn off, you’ll gain weight. If you burn more than you take in, you’ll lose weight.

  Why Protein Helps Burn Calories

  When it comes to human metabolism, this basic law of physics is a bit more complicated: All calories are not created equal. Protein is different from carbohydrates and fats.

  How do you burn calories? Some you burn at a very low level all the time as part of your “resting metabolism”—for basic, unconscious functions such as beating of the heart, breathing, and digestion. You burn more calories when you move and still more when you exercise.

  The common wisdom is that there are only two ways to burn more calories than you eat: Eat less or move around—exercise—more.

  But there’s another way to burn calories—a subtle process that can work wonders over weeks and months to create a substantial, long-term caloric deficit. Best of all, you don’t even have to get out of bed to reap the benefits. This amazing phenomenon is called the “thermic effect,” and the key to making it work is protein.

  This is how it works: During the digestive process, your body breaks down food into its basic components—carbohydrates, fats, and proteins—and turns them into energy it can use. There’s a trade-off: To get the energy from the food, the body must spend some of its own energy. There’s a scientific name for this use of energy to digest and metabolize food—“dietary-induced thermogenesis” (DIT). Carbohydrates and fats generate about the same low DIT. Protein’s DIT is huge in comparison—more than two and a half to three times greater. So, in order for the body to obtain energy from dietary protein, it must give up almost three times more energy than it needs for either fat or carbohydrates.

  What this means is that protein boosts your metabolism and causes you to lose weight more rapidly than the same caloric amounts of fat or carbohydrates. A study carried out at the Dunn Clinical Nutrition Center in Cambridge, England, by Dr. M. J. Dauncey and colleagues showed that during a twenty-four-hour period, a high-protein diet increased total energy expenditures by 12 percent (220 calories) compared to a calorically matched high-carbohydrate diet.

  Over six months—with absolutely no increase in exercise or decrease in caloric intake—a high-protein diet could cause you to lose 10 to 15 pounds. Over those same six months—with increased exercise and a somewhat decreased caloric intake—a high-protein diet could cause you to lose 30 to 75 pounds!

  Think about it. You don’t have to cut calories one bit. You can lose 20 to 30 pounds in a year with utterly no change in the quantity of food you eat or even any change in your exercise habits. Or a lot more than that if you exercise more or eat less. That’s just what happened with Dean.

  Losing 75 Pounds in Six Months: Dean’s Story

  In April 1999, Dateline NBC ran a feature story of my research into Paleo diets and interviewed Dean Stankovic, age thirty-two. Dean’s weight had fluctuated wildly on his 6-foot, 3-inch frame since his graduation from high school, at one point reaching a high of 280 pounds. Before he adopted the Paleo Diet, Dean had tried dozens of diets. Although Dean was very determined to lose weight, he just couldn’t seem to stick to traditional low-calorie diets like the one created by Weight Watchers. They made him feel hungry all the time. Worse, on all of these diets, his weight dropped at first—but the longer he stayed with them, the slower the weight loss became. This is because the body’s metabolic rate slows down to conserve body stores during periods of starvation—which is exactly what low-calorie diets are. Eventually, after a few months of starvation with these low-calorie diets, no matter how strong his willpower and resolve, Dean always went back to his normal way of eating—basically, the standard American diet.

  Dean had tried the high-fat, low-carbohydrate diets advocated by Dr. Atkins and others. He lost weight with these diets but complained of a low energy level, lethargy, and constant fatigue. He also believed that all of those fatty, salty, bacon-and-egg breakfasts, greasy sausages and salami, and fatty cheeses just couldn’t be good for his body. And these diets became boring. It was fun at first to trade in one evil (sweets and starches) for another (fats). But after a while he craved apples, peaches, and strawberries—any fresh fruit. Dean just couldn’t imagine going through the rest of his life eating only tiny amounts of fruits and veggies. This was not a lifelong way of eating! Life was not worth living when all he had to look forward to was fatty meats and cheeses, cream, and butter. Dean’s mind and body rebelled, and he found himself once again down in the dumps—back to his old diet and back to his old weight.

  In the fall of 1998, Dean met a young woman who had been eating in the Paleo manner for a number of years. She gave Dean some of my writings and dietary recommendations. After a few false starts, Dean began the Paleo Diet in earnest and started to lose weight steadily. By the spring of 1999, after six months on the Paleo Diet, he had lost 70 pounds and was down to a svelte 185 pounds. Dean’s opening remark on Dateline NBC—“It is a very satisfying diet; I don’t feel hungry”—is a characteristic comment, echoed by almost everyone who gives this way of eating a try. Two years later, Dean has kept the weight off and sums up his feelings this way: “I consider it more than just a diet; it’s more of a lifestyle. I think it is one of the greatest diets ever created. I have no plans to go back to my old ways.”

  Protein Satisfies Your Appetite

  Protein’s high DIT is not the only reason you lose weight when you start eating more lean animal protein. Protein also affects your appetite. Protein satisfies hunger far more effectively than either carbohydrate or fat. Dr. Marisa Porrini’s research group at the University of Milan in Italy has found that high-protein meals are much more effective than high-fat meals in satisfying the appetite.

  High-protein meats also do a much better job of reducing hunger between meals than do high-carbohydrate vegetarian meals. Dr. Britta Barkeling and colleagues at the Karolinska Hospital in Stockholm served twenty healthy women lunches of identical caloric value; the women ate either a high-protein meat casserole or a high-carbohydrate vegetarian casserole. The researchers then measured how much food the women ate at dinner. The women who had eaten the meat casserole ate 12 percent fewer calories during their evening meal. As this study illustrates, protein’s powerful capacity to satisfy hunger not only influences how much you eat at the very next meal but also how much you’ll eat all day long.

  At the Rowett Research Institute in Great Britain, Dr. R. James Stubbs and colleagues fed six men a high-protein, high-fat, or high-carbohydrate meal at breakfast and then monitored their feeling of hunger for the next twenty-four hours. The high-protein breakfast suppressed hunger much more effectively than the other two breakfast meals did—even more than the high-fat breakfast. These experiments and many others have convincingly shown that if you want to feel less hungry and stay less hungry, lean animal protein is your best line of attack.

  Theoretically, any leftover calories—whether they’re from protein, carbohydrates, or fats—would count as a calorie “surplus” and result in weight gain. In reality, the body doesn’t work that way. It is very difficult and inefficient for the body’s metabolic machinery to store excess protein calories as fat. The surplus almost always comes from extra fats or carbohydrates—and these are the foods that most frequently make you fat.

  It is impossible to overeat pure protein. In fact, you couldn’t gain weight just on lean, low-fat protein if your life depended on it. The body has clear limits, determined by the l
iver’s inability to handle excess dietary nitrogen (released when the body breaks down protein). For most people, this limit is about 35 percent of your normal daily caloric intake. If you exceed this limit for a prolonged stretch of time, your body will protest—with nausea, diarrhea, abrupt weight loss, and other symptoms of protein toxicity.

  But remember, protein is your best ally in waging the battle of the bulge—and when it is accompanied by plenty of fruits and veggies and good fats and oils, you will never have to worry about getting too much protein. Now let’s take a look at the next major reason why the Paleo Diet causes you to lose weight without nagging hunger.

  Promoting Weight Loss by Improving Your Insulin Sensitivity

  The Paleo Diet promotes weight loss not only because of its high protein level that simultaneously revs up your metabolism and reduces appetite, but also because it improves your insulin metabolism.

  Insulin resistance is a serious problem, and most people who are overweight have it. In insulin resistance, the pancreas (the gland that makes insulin) must make extra insulin to clear blood sugar—glucose—from the bloodstream. There’s a bit of a “chicken and egg” argument as to which event happens first. Does being overweight cause insulin resistance or vice versa? Scientists aren’t entirely sure. However, once insulin resistance starts, it prompts a domino effect of metabolic changes that encourage weight gain. The body frequently stores more fat, for one thing. For another, excessive insulin in the bloodstream can cause low blood sugar (a condition called “hypoglycemia”). The body’s response to low blood sugar is: “Hey—we’re in trouble. We’d better eat something fast!” Low blood sugar stimulates the appetite, and this can be deceptive: it causes you to feel hungry even if you’ve just eaten.

  The good news is that what you choose to eat—protein, fats, or carbohydrates—can influence the progression of insulin resistance. Dr. Gerald Reaven’s research at Stanford University has shown that low-fat, high-carbohydrate foods hinder insulin metabolism. But high-protein diets are known to improve insulin metabolism. Dr. P. M. Piatti and colleagues at the University of Milan put twenty-five overweight women on one of two diets. The first contained 45 percent protein, 35 percent carbohydrates, and 20 percent fat. The second contained 60 percent carbohydrates, 20 percent protein, and 20 percent fat. After twenty-one days the women on the high-protein diet had significantly improved insulin metabolism, but those on the high-carbohydrate diet actually got worse.

  With all these benefits, it seems obvious that lean protein should be the starting point for all weight-loss diets. Prior to 2002, only three clinical trials of high-protein diets had been conducted. All three investigations found high-protein diets to be excellent—far better than low-fat, high-carbohydrate diets—at promoting weight loss.

  Dr. Arne Astrup’s nutritional research group at the Royal Veterinary and Agricultural University in Copenhagen, Denmark, studied weight loss in sixty-five people placed on either high-protein or high-carbohydrate, reduced-calorie diets. After six months, those in the high-protein group had lost an average of 19.6 pounds—and 35 percent of the participants in this group had lost more than 22 pounds. The people in the high-carbohydrate group, however, lost only an average of 11.2 pounds; only 9 percent of the people in this group lost 22 pounds.

  Dr. Hwalla Baba and colleagues at the American University of Beirut demonstrated almost identical results when they put thirteen overweight men on high- and low-protein, reduced-calorie diets. After only a month the average weight loss for men on the high-protein diet was 18.3 pounds compared to only 13.2 pounds for the high-carbohydrate group.

  Dr. Donald Layman, a professor of nutrition at the University of Illinois, studied twenty-four overweight women who for ten weeks were on 1,700-calorie-a-day diets. Half of the women followed the current USDA Food Pyramid guidelines recommending a diet of 55 percent carbohydrate, 15 percent protein (68 grams per day), and 30 percent fat. The other half had a diet of 40 percent carbohydrate, 30 percent protein (125 grams a day), and 30 percent fat. The average weight loss for both groups was about 16 pounds, but the high-protein group lost 12.3 pounds of body fat and just 1.7 pounds of muscle compared to 10.4 pounds of body fat and 3 pounds of muscle for the Food Pyramid group. Interestingly, the study also found that women on the higher-protein diet had higher levels of thyroid hormone, which indicates that they had a faster metabolic rate. The higher-protein diet also resulted in a noticeable drop in triglyceride levels and a slight increase in the good HDL cholesterol.

  In the eight years since I wrote the first edition of this book, numerous human clinical trials have conclusively demonstrated the superiority of high-protein diets in producing weight loss and benefiting overall health.

  What You Can Expect to Lose on the Paleo Diet

  When you start the Paleo Diet, you’ll probably realize—perhaps with a shock—just how much of your diet has been built around cereal grains, legumes, dairy products, and processed foods. Even most vegetarians must eat large amounts of grains and legumes to make their plant-based diets work, because it’s very difficult to get enough calories just from eating fruits and vegetables. Except for the 2,000 or fewer hunter-gatherers still remaining on the planet, none of the world’s people obtain their daily sustenance just from fruits, vegetables, lean meats, and seafood. When you start the Paleo Diet, you may choose to count yourself among the dietary elite—knowing that about 6 billion people on the planet aren’t eating this way. And yet just 10,000 years ago—a mere drop in the bucket of geological time—there wasn’t a single person who did not follow the Paleo Diet.

  Everything I’m telling you about how the Paleo Diet will affect your body weight, health, and well-being is based on scientifically validated information that has been published in high-quality, peer-reviewed scientific and medical journals.

  If you’re overweight, the Paleo Diet will normalize your weight. This means that you will steadily lose pounds, as long as you continue to follow the diet, until your weight approaches its ideal. Most people experience rapid weight loss within the first three to five days. This is mainly water loss, and it stabilizes fairly quickly. After that, how much weight you lose will depend on two things—how overweight you are to begin with and how many total “deficit” calories you accumulate. After the initial water loss, it takes a deficit of 3,500 calories to lose a pound of fat. It is not unusual for people who are obese (medically, this means people who have a body mass index (BMI) of greater than 30) to lose between 10 and 15 pounds each month.

  Sharing Success Stories

  Many people, in many countries, have adopted Paleo Diets to improve their health and to lose weight. You can read about their stories and triumphs at my Web address: www.thepaleodiet.com/success_stories/. You may also want to visit my blog (http://thepaleodiet.blogspot.com/), where Paleo dieters share experiences, offer support, and talk to one another about daily challenges, dietary issues, and health issues concerning the Paleo Diet lifestyle.

  Losing 45 Pounds and Healing Crohn’s Disease: Sally’s Story

  Sally is a manager for a large telecommunications company in Illinois. Her reasons for adopting the diet were primarily health-related. However, she also benefited from the diet’s remarkable ability to normalize excess body weight.

  In the fall of 1986, I became severely ill. It started with several months of unshakable diarrhea, followed by gut-wrenching pain. It became so bad that I could not keep any food down. I lost 70 pounds in three months, and I was only thirteen years old. I barely made it through my classes at school, and then I’d go home and sleep. My best friends no longer came over, my mother was sick with worry, and my father thought I was anorexic. When my symptoms began, doctors could not find anything wrong except for “perhaps some allergies.” And when my symptoms grew worse, I was shuffled back and forth between doctors and specialists, each speculating on tumors, liver disease, and other life-threatening conditions. I was subjected to every conceivable test: MRI [magnetic resonance imaging], ultrasounds, u
pper/lower GIs [gastrointestinal studies], blood tests, stool samples, urine tests, X-rays, throat scopes, and others. It took almost nine months to reach the diagnosis of Crohn’s disease.

  I was given large doses of prednisone [a steroid drug] and scheduled to have a portion of my bowels surgically removed if I didn’t respond to the medication. Within days of [taking] the steroids, I felt much better. Within weeks I was outside mowing the lawn and eating more in a day than I had eaten previously in a month. At the time, my medications were a miracle.

  For most of my life I have been cycling between steroids, anti-inflammatory drugs, and immune suppressors. All of these medications alleviated the symptoms, but none treated the underlying disease. My overall health slowly deteriorated. I was severely depressed and powerless to stop my life from slowly wasting away. When questioning doctors, I was given unhelpful speculations: “Crohn’s disease is genetic; it runs in families. It may be caused by a virus or bacterium, it is not contagious, and we do not know what causes this disease.” Every specialist I saw agreed that Crohn’s is not diet-related.

  By the time I graduated from college, I became determined to do something. I enrolled in graduate school to learn more about scientific research so that one day I might help find a cure. While in graduate school, I discovered literature about diet-related treatments for a whole range of degenerative illnesses, including Crohn’s disease. All of the diets used to treat Crohn’s disease are very similar to a Paleolithic diet. It became my turn to become responsible for my own health, and I started eating a strict Paleolithic diet. The results were amazing. Within a month I was 90 percent symptom-free. I felt like I had been reborn.