Debunking the "Zone Diet"
Enter the "Zone":
A Giant Leap Backwards
by Charles R. Attwood, M.D., F.A.A.P.
Anne, an old friend of mine, walked up to Barry Sears at the Tom Landry Sports Medicine and Research Center in Dallas.
She complained that the program outlined in his book, Enter The Zone -- more lean meat, egg whites, poultry and fish, while limiting many grains, vegetables, and fruits -- just didn't work for her. She didn't feel good, and her performance level (swimming) had declined. Anne was now back on her vegetables, fruits, and whole grains.
"Stay with what works best," he said, "but you know, Anne, it's not the fat and protein that's so important. It's the effect of carbohydrates upon hormones and insulin levels."
Though this was contrary to everything I had told her about nutrition, the book's message was loud and clear: "All those trendy high-carbohydrate diets," he had written, "may be increasing your risk of developing heart disease."
Excessive complex carbohydrates, according to Sears, also causes obesity by increasing insulin output and fat storage. This is the process, he insists, that creates bad eicosanoids leading to heart disease and cancer.
"To complete a 'Zone-favorable' meal," he advises, "always add fat, the building blocks for eicosanoids." While it's true that eicosanoids are hormones involved in many metabolic processes, the relation of "bad" eicosanoids to obesity and disease is at best a scientifically unproven gimmick. Unfortunately, however, it has captured the unquestioning reader's imagination.
Every few years since the early 1950's, someone has based a book on carbohydrate bashing. First, there were the Dr. Stillman's Diet and Dr. Atkins' Diet followed by The Scarsdale Diet, and finally, Enter The Zone. Now there are others: Michael and Mary Dan Eases's Protein Power and Rachael and Richard Heller's Health For Life.
And once again Dr. Atkins New Diet Revolution is back on the bestseller lists. According to Bonnie Liebman, at the Center For Science in the Public Interest, it's nothing new. "Miracle diets come and go like hemlines, hair-dos, and celebrity romances." Furthermore, they don't work; and all of them have the potential of raising low density lipoprotein (LDL) levels. And finally, what do these diets do for the authors themselves? Both Dr. Atkins and Barry Sears have exceeded the upper limits of weight recommended by federal guidelines.
A vegetarian diet, according to Sears, is as far as you can get from The Zone. He ignores the fact that individuals who eat vegetarian diets have far less heart disease and cancer, and tend to be leaner, not fatter. Moreover, most clinical studies conducted during the last half century, clearly show that a high-protein, high-fat, low-carbohydrate diet leads to higher rates of heart disease, stroke, hypertension, adult onset diabetes, and many types of cancer.
The relationship of animal fat to cancer is stronger than ever before. According to new studies released by the Environmental Protection Agency, potent carcinogens from industrial wastes, such as dioxin and other chlorinated compounds, are known to be concentrated in the animal fat of meat, fish, and dairy products. On the other hand, vegetables, fruits, and grains contain only small amounts of these compounds.
So why is the Zone diet so popular? It's followers defend it vehemently, largely because they find the rapid weight loss irresistible. Like most low carbohydrate diets, however, a great deal of the weight loss is dehydration. Ordinarily, three grams of water are stored with every gram of carbohydrates in the form of glycogen in the liver and skeletal muscles. When this is sharply limited, the desperate "zonies" think they are losing up to a pound of fat a day. It's also low in calories (about 1,700), causing the unhealthy depletion of lean body mass along with the minimal fat loss.
Also, without careful monitoring, this type of diet may lead to "ketosis" (an unnatural form of acidosis), which often causes some degree of anorexia and even euphoria. Sears denies that this happens with the amount of carbohydrates he allows.However, Dr. Atkins, another proponent of high protein, high fat, low carbohydrate consumption, considers ketosis to be a useful and necessary state. If ketosis sounds familiar, it's also the result when insulin-dependent diabetics can't metabolize carbohydrates without their insulin injections -- a state leading up to diabetic coma.
The Sears diet recommends that one get 30 percent of calories from fat, 30 percent from protein, and 40 percent from carbohydrates. Here, it should be obvious that these are approximately the proportions already consumed in most Western countries, including the United States, where heart disease and cancer are rampant. Furthermore, with such low intakes of complex carbohydrates, it appears that Sears' recommended diet would be deficient in vegetables, fruits, and whole grains -- and would contain inadequate fiber. Adding insult to injury, this level of protein consumption may promote calcium loss and osteoporosis.
Sears has very little to say about cholesterol levels in his book. He writes, "if cholesterol is such a villain, why does the body make so much of it?" The real heart disease risk, he says, is "hyperinsulinemia and bad ecosinoids." He is either unaware that practically all published reports indicate just the opposite, or he hasn't thoroughly read his own book -- written with the help of professional magazine writer, Bill Lawren. It's riddled with such comments as, "eating fat doesn't make you fat." It cautions that such foods as potatoes, brown rice, bread, corn, carrots, pasta, bananas, dry breakfast cereals, apple juice and orange juice may be harmful to your health. None of the references quoted, backing these conclusions, have ever been published, and the book does not contain a reference section or a bibliography.
So in summary, a half century of scientific research, first from Ansel Keyes' population studies in the 1950's to T. Colin Campbell's ongoing Cornell-Oxford-China Nutrition project today, has given us a wealth of data supporting the health benefits of carbohydrates. "The Zone" would be a giant step backward. A little weight loss, which is quickly regained when the diet is no longer tolerated, isn't worth the inevitable long-term health risk.