Debunking the "Zone Diet"
Enter the "Zone":
A Giant Leap Backwards
Charles R. Attwood, M.D., F.A.A.P.
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
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
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.