预防胜于治疗
传播最新健康知识、记录恢复健康消息、推荐及时健康产品
People all across this country are asking, "Should I be on a high-protein or a low-protein diet to lose weight?" Experts, many of them with credentials, will encourage you in both directions. Right now the high-protein message appears to be winning out among the masses. The best selling diet books on the market--Enter the Zone by Barry Sears, Protein Power by Michael and Mary Eades, Dr. Atkins' New Diet Revolution by Robert Atkins, and Healthy for Life by Richard and Rachael Heller--are all high-protein, low-carbohydrate. At health shows I find these authors swarmed by followers; even in the face of all the well-publicized scientific evidence that says these diets provide only short-term weight loss, and they are made up of foods known to cause serious diseases.
Why the Popularity?
Many people are desperate to lose weight (and some to become healthier). Their pleas for help have gone unanswered for one reason or another. Therefore, any new chance for help is welcome, especially if it requires little effort. The foods recommended in high-protein diets are the very same rich foods we were all raised with and learned to love in America. They are the juicy roasts, salty hams, braised lamb chops, lobsters drawn in butter, pungent cheeses, salty fried eggs, and crispy bacon. Foods most people still considered their birthright to enjoy--being born into the wealthiest nation on earth. Tastes are hard to change. Preach what people want to hear and you have an immediate following, because naturally we all like to hear good news about our bad habits.
These high-protein diets are often sold to the public with the claim that there is something unique, even mystical, about the effects of protein on the body that makes all well established dietary advise obsolete. For example, the author of the Enter the Zone claims the problem with our weight and health, specifically heart disease, is that high carbohydrate diets promote excessive production of specific hormones--insulin and "bad" eicosanoids. The secret to weight loss and preventing heart disease is controlling hormones into a narrow range referred to as "the Zone," by adding more protein to the diet than is commonly consumed or recommended (30% vs 12%). People love to hear there is a gimmick, like "entering the Zone," that will somehow trick their body into losing extra fat without having to give up the foods they love, or even worse, exercise. They're also happy to hear it's not their fault they're fat, "It's my hormones that are the real culprit, I don't have to feel guilty about being a glutton and not exercising."
High-protein diet gurus are usually establishment bashers, they claim they have the truth and all the other doctors, dietitians, and scientists are wrong. People love to hear the experts are wrong again. Even better, they like to believe there's a conspiracy by all these establishment professionals to keep them fat and sick.
One of the most important reasons for the popularity of high protein diets is they work--people lose lots of weight fast--but it's mostly water. Stored carbohydrate contains large amounts of water. Switching to a low-carbohydrate diet results in the loss of these stores and the associated water, with an impressive initial weight loss. In addition, if the diet is low enough in carbohydrate, like the Atkins diet, then the body goes into ketosis, causing suppression of the appetite, thereby you eat and suffer less. I call these "the make yourself sick diets," because they simulate metabolic changes that take place during illness--ketosis is a natural state that occurs when people are sick--a time when they shouldn't be gathering and preparing food, but rather recuperating.
Sickening Foods
The foods recommended for a high protein diet are mainly meat, egg, and dairy products, which are high in cholesterol, fat, and animal protein; and deficient in dietary fiber, carbohydrate; and are often highly contaminated with chemicals and microbes; and have serious vitamin and mineral imbalances.
"Nutrition and Health in the United States," published under the direction of Surgeon General C. Everett Koop MD in 1988 put to rest all controversy concerning whether or not diet is fundamental in the cause, prevention, and treatment of common diseases. "The Report's main conclusion is that overconsumption of certain dietary components is now a major concern for Americans. While many foods are involved, chief among them is the disproportionate consumption of foods high in fats, often at the expense of foods high in complex carbohydrates and fiber that may be more conducive to health." Similar recommendations to eat fewer animal products and more plants foods have been made by every other health organization, including the Senate Select Committee on Nutrition, American Heart Association, the American Cancer Society, The Diabetic Association, and the American Dietetic Association. They all believe, to one degree or another, that the chronic illnesses plaguing modern Western society are caused by an unhealthy diet and lifestyle, and that improved health comes from eating fewer animal products and a more plant food-based diet.
The diseases believed to be caused by meats, egg, and dairy products include most cases of: obesity, heart diseases, adult diabetes, breast, colon, and prostate cancer, gallbladder disease, osteoporosis, kidney failure, kidney stones, multiple sclerosis, rheumatoid arthritis, constipation, diverticulosis, hemorrhoids, and hiatal hernia to name a few well studied diseases. You don't have to be a trained nutritionist to see the risk of becoming sick increases the more of these unhealthy foods that are eaten--like with high-protein diets.
Protein Damage
Protein is metabolized by the liver and excreted by the kidneys into the urine. A high protein load causes damage to these organs. By the eighth decade of life people in affluent societies commonly lose about 30 percent of their kidney function (J Gerentol 31:155, 1976). This loss is believed to be secondary to overwork of the kidneys caused by the amount of protein typically consumed on the American diet, 12% to 15% protein (N Engl J Med 307:652, 1982). The Zone diet recommends 30% protein, and even more protein is found in other high-protein diets. Low protein diets (4% to 8%) are used routinely to treat patients with liver and kidney failure.
High protein diets cause serious metabolic changes that lead to bone loss and kidney stones. Red meat, poultry, fish, shellfish, and eggs are acidic in make up. Vegetable foods are alkaline by nature. The body guards its acid-base balance (pH) carefully so that all of the pH-dependent biochemical reactions take place normally. The dietary-derived acid load from high-protein animal foods must be buffered. The primary buffering system of the body is the bones which dissolve for that purpose into phosphates and calcium. The alkaline phosphate then buffers the animal-food derived acid. This is the first step in bone loss that leads to osteoporosis. The second step leading to osteoporosis consists of changes in kidney physiology caused by the acid, the sulfa containing amino acids (plentiful in meat), and the increased solute load, all resulting in a loss of large amounts of bone material, including calcium, into the urine. The presence of this bone material in the kidney system also lays the foundation for calcium-based kidney stones.
The Nurse's Health Study recently found women who consumed 95 grams of protein a day compared with those who consumed less than 68 grams a day had a 22% greater risk of forearm fractures (Am J Epidemiol 143:472, 1996). Metabolic ward studies done on people have found a negative calcium balance is created when 95 grams of protein are consumed with 500 mg of calcium. The calcium intake must be raised up to 800 mg before calcium balance is achieved (the calcium entering the body is the same as the amount leaving). People following the Zone diet commonly consume 100 grams of protein and less than 800 mg of calcium. Athletes attempting to follow the Zone diet will consume 140 grams or more of protein a day. Even with a very high calcium intake of 1400 mg daily these people are still in negative calcium balance.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Impossible Advice
On June 9, 1997, I met Barry Sears, the author of the number one national best seller, Entering the Zone, at Bally's in Las Vegas for the first of our 3 debates (see page 7 for more information). After telling a crowd of nearly 4000 people the virtues of his diet for controlling insulin and eicosanoid levels with resulting weight loss and improved health, I proceeded to explain why his diet is merely a semi-starvation diet and like all such diets it is impossible to follow for any length of time. I used Barry Sears as an example:
Barry Sears weighs 210 pounds and is 6'5" according to information from his book. His diet is based on 30% of the calories from protein, 30% fat, and 40% carbohydrate. He says he eats 100 grams of protein a day. He has been following his diet for 4-5 years. He says he is still on his diet because he still needs to lose more weight.
If Barry Sears eats 100 grams of protein that translates into 400 calories of protein (1 gram of protein = 4 calories). Since the proportions of the diet are 30/30/40, this means he also consumes 400 calories of fat, and about 500 calories of carbohydrate. His total calorie intake is therefore 1300 calories per day. A conservative estimate of his actual needs would be over 2300 calories a day, with only sedentary activity. This means every day he is 1000 calories short of his needs. Every week he comes up 7000 calories short, which must be made up from his fat stores. One pound of fat amounts to 3500 calories. Therefore, Barry Sears must lose 2 pounds of fat a week on his diet. Every year by calculation he loses 104 pounds. Since he says he has been on his diet for 4 to 5 years this means he has lost over 400 pounds.
At this point in the debate I asked him, "Barry Sears: A) Did you start your diet at over 600 pounds? B) Do you defy the laws of nature? or C) Is it that you cannot and do not follow your own diet?"
Like all calorie restricted diets, the Zone diet is next to impossible to follow for very long because it hurts to be hungry. His program is also impossible because the dietary rules are complicated and foods recommended are unhealthy and unappealing.
Coincidentally the June issue of Prevention Magazine came to the same conclusions. They made up a day in the Zone for their article. The meals consisted of 6 egg whites, ½ cantaloupe, 1 kiwifruit, and 3 macadamia nuts for breakfast, Lunch served 3 oz. of skinless white chicken, 1 cup each of steamed asparagus, broccoli, green beans, and 1 tsp of olive oil. Dinner was 3 oz. of turkey breast salad, 4 cups of spinach, 3 cups of cucumber slices, 2 tomatoes, and 1 tsp. of olive oil. Afternoon snack was ¼ cup of low-fat cottage cheese, ½ medium pear, and 3 olives. Evening snack was ¼ cup egg substitute (scrambled), 1 medium plum, ½ tsp. natural peanut butter. This provided 1,209 calories, 110 grams of protein (37%), and 646 mg of calcium. The authors of this article asked "How long could you eat this way?"
During the next round of the debate I pointed out that Barry Sears had not answered my question. Therefore, I must assume he cannot and does not follow his own diet. He admits to only 35 pounds of weight loss over the past 4 years (less than 9 pounds a year), therefore he must be consuming at least 2300 calories a day. This leaves two possibilities:
If he is following his rule that to be in "the zone" you must adhere to proportions of 30/30/40; then based on a 2300 calorie intake he must be eating 173 grams of protein and 77 grams of fat daily (1 gram of protein = 4 calories and 1 gram of fat = 9 calories). Therefore he must be in a high-protein, high-fat zone. However, he admits to eating only 44 grams of fat a day, so the next possibility is more likely.
If he follows his rule that he eats a specific amount of protein daily to be in "the zone" and for him that's 100 grams of protein a day; then based on 2300 calories of a day his diet would be 17% protein, 17% fat and 66% carbohydrate, which would place him in a high-carbohydrate zone.
My next question to him was, "Barry...please tell us--are you on a high-protein (Atkins-Type) diet or are you on a high-carbohydrate (McDougall-Type) diet?" He still wouldn't answer. He finally said something about not being interested in weight loss, but was really trying to protect himself from heart disease, since he has a strong family history.
The Heart Disease Zone
Seems kind of strange to think of a diet centered around beef, pork, lamb, chicken, eggs, bacon shrimp, lobster, and cheese preventing heart disease. But, Sears reasons that too much insulin production by the body is the primary culprit for causing heart disease, and the Zone diet will control insulin and prevent heart disease. He feels so strongly about this that he claims in his book that a very low-cholesterol, low-fat diet will actually cause heart disease. After looking over Dr. Dean Ornish's research he concludes, "My guess is that the people who stay on his (Ornish's) program will ultimately have more heart attacks, more strokes, and a higher cardiovascular death rate than the dropouts." He bases this on the fact that "good" HDL-cholesterol went down in Ornish's patients and triglycerides went up.
During the debate I pointed out to him that Ornish had corrected him over a year ago, by providing him the data showing his patients on a high-carbohydrate diet had a 50% decrease in risk of cardiovascular deaths. Sears admitted his error to Dr. Ornish and promised to make corrections in his book, but has not.
On a healthy low-fat, low-cholesterol diet "good" HDL-cholesterol goes down because all fractions of cholesterol go down. Worldwide the lowest incidence of heart disease is found where people eat the lowest cholesterol diets and also have the lowest HDL-cholesterol levels (2:367, 1981). Feeding cholesterol raises HDL-cholesterol (N Engl J med 325:1704, 1991). A long-term study of patients on a high-carbohydrate diet showed less risk of death from heart disease compared to those on the American diet (JAMA 173:884, 1960).
More Zone Nonsense
Barry Sears makes numerous statements in his books and at public appearances that are incorrect, and I believe he is well aware of the inaccuracies, but refuses to correct them. Much of this same misinformation is used by promoters of other high-protein diets. Examples include:
Fat Doesn't Cause Obesity:
Sears: Eating fat doesn't make you fat. We are consuming less fat than 10 years ago and getting fatter, therefore dietary fat cannot be the culprit.
Truth: We are consuming the same amount (actually a little more) of fat now than before. But, in addition, we are consuming over 250 more calories of refined flours and sugars over the past 15 years. Because of the added refined carbohydrates, the percent of fat in the diet has gone down between 1980 and 1990 (men 38% to 34%, women 37% to 34%), but the actual amount (grams) of fat consumed has remained the same (men 99.8 to 98.8, women 62.6 to 67.8), and the diet American diet now has more calories (men 2,457 to 2,684, women 1,531 to 1,805). The reason for the rise in obesity is no mystery--Americans eat a high-calorie, high-fat diet.
Carbohydrates Increase Heart Disease
Sears: A high-carbohydrate diet for cardiovascular patients may be dangerous to their health. Experiments show high carbohydrate diets increase the risk factors for heart disease, by raising cholesterol and triglycerides, and lowering HDL-cholesterol.
Truth: You can design such experiments to show triglycerides go up by feeding refined carbohydrates to subjects, and by overfeeding subjects (cholesterol still goes down and I explained the effect on HDL-cholesterol above). When subjects are allowed to eat only until they are full (not force-fed) their cholesterol level falls, their triglyceride levels don't go up significantly, and they lose weight (JAMA 274:1450, 1995). A study of 1250 of my patients shows triglyceride levels decrease an average of 10 mg/dl, and people who start with levels over 600 mg/dl have a 311 mg/dl reduction in 11 days. Therefore, eating as much as you want (but not more than you want) of a healthy low-fat, no-cholesterol diet lowers three important risk factors for heart disease--cholesterol, triglycerides and body weight.
Rice Means More Heart Disease
Sears: The Chinese are an example of how people on a high carbohydrate diet (rice) are as likely to have heart disease as Americans. Using the American Heart Association data, he points out, Urban Chinese have almost as much cardiovascular disease as in the US.
Truth: Cardiovascular disease is not the same as heart disease. In China, half of this cardiovascular disease is represented by strokes (from old age and high-salt diets), less than one-third is due to heart attacks (ischemic heart disease). In the US nearly two-thirds of the cardiovascular disease is due to heart attacks (and one-sixth is due to strokes). Besides, the 1993 figures he uses reflects the modern Chinese diet, which much higher in fat and cholesterol than a few years back, especially for those people in the cities (urban)
Fat Improves Athletic Performance
Sears: Athletes perform better on a high-fat diet. A high carbohydrate diet is overrated for elite athletes. A high-carbohydrate diet actually limits the performance of highly trained endurance athletes.
Truth: Carbohydrate, not fat, is the primary fuel for exercise at or above 70% of aerobic capacity, the intensity at which most people train and compete. Fat only becomes available for fuel after 20 minutes of exercise; therefore most people never exercise enough to lose body fat. Almost every study of trained athletes shows carbohydrate fed before and during the event improves an athlete's performance. Carbohydrate fed after the event replenishes the athlete's glycogen stores for the next race.
Keeping Correct Insulin Levels
Sears: Reaching "the Zone" requires precise control of the protein-to-carbohydrate ratio. Protein counteracts the carbohydrates you eat to keep insulin levels in balance. High levels of insulin generated by too much carbohydrate drive you out of "the Zone."
Truth: There is no evidence that eating equal amounts of protein and carbohydrate at every meal, as Sears suggests, lowers insulin. According to Dr. Gerald Raven from Stanford University. "Protein--when eaten alone--increases insulin secretion. I see no reason in the world why it would be any different if protein were eaten with carbohydrate" (Nutrition Action Newsletter Jul/Aug 1996). A study from the Lancet found beef fed with glucose raised insulin levels twice as high as glucose alone and four-times as high as beef alone. The authors concluded, "Ingestion of glucose plus protein is followed by a very large increment in plasma-insulin, of such a magnitude as to suggest synergism between glucose with aminoacid (protein) with respect to insulin release." (Lancet 2:454, 1966). The diet fed these subjects met the zone specifications of 30/30/40 for ideal an protein-to-carbohydrate ratio: 27% protein / 30% fat / 43% carbohydrate. A study of adult-type diabetics, people with insulin resistance, and normal people found 3-weeks of a high-carbohydrate, low-fat diet and exercise lowered insulin levels significantly (Am J Cardiol 69:440, 1992).
Ecosanoids are the Key
Sears: Eicosanoids are the body's super-hormones. Virtually every disease state--whether it be heart disease, cancer, obesity or autoimmune diseases, like arthritis and multiple sclerosis--can be viewed as an imbalance of eicosanoids. To keep the eicosanoids in a healthy balance you need to eat three grams of protein for every four grams of carbohydrate.
Truth: Sears bases his whole diet theory on these hormones, yet he has never measured the eicosanoid levels in people--so he really doesn't know the response to his diet. Gerald Raven of Stanford says, "I find it hard to swallow that anyone could really believe eicosanoids are the key to all health and disease" (Tufts U Diet & Nutrition Newsletter, May 1996). William Evans, PhD, director of the Noll Physiological Research Center at Penn State University says, "There aren't any studies that I'm familiar with that suggest they're dangerous in any way. Anyone who tries to sell diet as the key to stemming ‘bad' eicosanoids is capitalizing on an unfounded idea" (same Tufts Newsletter).
What to Tell Your Friends
"You can burn more fat watching TV than by exercising" and "...many people following high-carbohydrate diets might just as well be eating candy bars" are some of the ridiculous statements found in Sears' book and people still want to believe him; therefore, it seems like an impossible task to try to help those friends and family members who are attracted by "high-protein diet preachers."
Try to get them see the big picture. If carbohydrates were bad for people then the Japanese living in Japan on a rice-based diet would be fat and sickly. When they moved to the US and switched to a lower-carbohydrate, higher-fat and -protein diet they would become thinner and healthier. The truth is the Japanese are among the slimmest, most energetic, longest lived, healthiest people on earth. Furthermore, they take on common American diseases when they change to the American diet. If high-protein diets, which means meat, egg, and dairy products, were so good for us then people who subsist on these foods (most Americans) would be the thin and healthy, and vegetarians would be fat and sick. In general, the opposite is the case.
Along this same line of thinking, ask your friends to closely observe the personal appearance of these experts making all these dietary recommendations. You will be struck by how fat and sickly most of them look. From where I stand, I must conclude that they do eat high-protein foods and lots of them.
In the long run these controversial diets are extremely important (even though some people get hurt along the way). The worst thing that can happen to the truth is for people to show no interest. This high-protein craze has made the country's top doctors, dietitians, nutritionists, sports experts, and other scientists closely examine the scientific research on nutrition and health. Almost every article on the subject these days brings up the damaging effects of protein on bone health leading to osteoporosis. Before this controversy all they would talk about is the need for calcium. The harm from eating refined foods, and sugars in all forms of the very popular nonfat cookies and cakes is now being emphasized. Soon the pendulum will swing back to a high carbohydrate, vegetarian diet and hopefully more people will make this their lifestyle as the truth becomes more widespread. (Read the preface of the McDougall Plan to see the historical scope of this debate)
You can obtain a 1-hour audio tape copy of this debate by sending $10 to McDougall/Sears Debate, PO Box 14039, Santa Rosa, CA 95402. (P & H included in cost).
http://www.drmcdougall.com/med_hot_protein_diets.html
