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The Zone--a euphoric state where the mind and body work at
peak efficiency and hum away in biochemical equilibrium. Sounds
wonderful, doesn't it? Just the thought of being able to "enter
the zone" has drawn thousands to Barry Sears' best selling book
on the subject and continues to have a devoted following.
The come-ons on the cover of the book make wide promises.
We're told that by following Sears' recommendations, we'll lose
weight permanently, prevent disease, achieve maximum physical
performance, enhance mental productivity and even reset our
genetic code. Is The Zone Diet all it claims to be, just another
fad diet that eventually will go the way of all fad diets?
The Zone Diet includes both healthful and not so healthful
recommendations. It promotes eating regular meals, which is good,
and is low in calories. Most people who follow The Zone Diet lose
weight, and for obvious reasons. When the author uses himself as
an example, he says he should consume a mere 1,332 calories a day
to follow the diet. This is considered a low-calorie diet even
for a small woman. It's a very low-calorie diet for Sears, who
stands 6-foot-5- inches tall and weighs 210 pounds. So, while the
diet is low in calories, it's too low in calories to serve as a
long-term diet regime.
Another interesting anomaly is that although the book bashes
high-carbohydrate diets and promotes fat as the secret to
athletic success, the diet itself is relatively low in fat
(restricting fat to no more than 30 percent of total calories.)
Further, only those fats high in monounsaturated fatty acids,
such as found in peanut, olive and canola oils, and fats high in
omega three fatty acids, such as found in fish oils, are
promoted. Saturated fats, found in meats and dairy products, are
restricted. Given its low overall caloric level, the diet
actually is quite low in fat grams. These recommendations are
consistent with the Food Guide Pyramid and with available
scientific data regarding diet, obesity and heart disease. Not
only will people who follow the diet lose weight, but as with
other low-fat, low-calorie diets, overweight people with insulin
resistance should see improved glucose control as well,
especially if combined with physical exercise.
Where the diet leaves conventional wisdom, and is not
recommended for long-term use, is its promotion of diets higher
in proteins and lower in carbohydrates than commonly recommended.
Carbohydrates, not proteins, are the preferred source of energy
for the body. For protein to be used for energy, nitrogen must
first be removed and eliminated, which can overtax the kidneys.
Even Sears notes that a high-protein diet is not recommended for
people with impaired kidney function.
The Zone Diet limits carbohydrates to no more than 40
percent of total calories. This is far lower than the 50 to 60
percent commonly recommended. According to Sears, when too much
carbohydrate is consumed, a hormonal message via insulin is sent
to the body saying, "store fat." In actuality, fat gets stored
when calorie intake is higher than calorie expenditure,
regardless of where those calories came from.
Finally, the metabolic pathways presented in The Zone, which
supposedly connect diet, insulin-glucagon, and eicosanoids may
sound impressive, but simply do not exist in standard nutrition
or biochemistry texts. The idea that The Zone Diet, or any diet,
completely controls the secretion of insulin and glucagon is not
supported by the relationship between nutrition and
endocrinology.
The bottom line is that The Zone Diet is based on half
truths, mixed messages and theories not yet grounded in peer-
reviewed research. Further, the long-term effects of the proposed
diet have not been examined. Like other reduced-calorie diets, it
will support weight loss for most individuals. But just how
healthy and permanent the weight loss is, remains to be seen.
For more information, contact your local
Colorado State University Extension office.
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