mentionscalciumand omega-3 fatty acid supplementa-
tion. Other supplements may also be necessary.
Research and general acceptance
The core of the Zone diet is that everything a
person eats should have a balance of 40% carbohy-
drates, 30% protein, and 30% fats. The 30% fats fits
in well with what many dietitians and nutritionists
recommend, and Sears emphasizes the use of olive oil
and canola oil, both high in monounsaturated fats
which are considered good for the body. However,
30% protein is considered high by many nutritionists
and 40% carbohydrates is considered low. The federal
health guidelines, Dietary Guidelines for Americans
2005, recommend consuming food in the proportions
of 55% carbohydrates, 15% protein, and no more
than 30% fats. These guidelines also recommend sub-
stantial consumption of whole grain products that are
severely limited on the Zone diet.
In a review of the Zone diet published inJournal of
the American College of Nutritionin 2003, the author
questions the emphasis placed on the hormonal con-
trol of weight. He argues that although it is well docu-
mented that carbohydrates stimulate the production
of insulin and proteins stimulate the production of
glucagon, this occurs only when single nutrients are
consumed. In a mixed meal consisting of protein, car-
bohydrates, and fats, such as those required by the
Zone diet, the situation is much more complex and
Sear’s conclusions about hormonal response are sim-
plistic. In the same article, the author questions the
emphasis put on the role of controlling the production
of eicosanoids through diet.
The claim that the Zone diet allows individuals to
perform at peak physical performance is refuted by
several studies by sports nutritionists who feel that
limiting carbohydrates can harm athletic perform-
ance, especially among endurance athletes.
In an effort to determine which of several popular
diets helped people keep weight off, researchers at
Tufts-New England Medical Center in Boston assigned
a group of volunteers to one of four diets: Atkins, Dean
Ornish,Weight Watchers, and Zone diet. The found
that regardless of the initial amount of weight lost, after
one year, losses were only about 5% in all programs,
meaning that these diets were all equally ineffective in
helping most people keep weight off. These results were
published in 2005 in the prestigiousJournal of the
American Medical Association.
In general, dietitians and nutritionists believe
that any benefit from the Zone diet comes from the
reduction of calories and subsequent weight loss.
They tend to feel that the same result can be achieved
with a less complicated diet low in fats and high
in fruits, vegetables, and whole-grain carbohydrates.
They also question whether individuals on the Zone
Diet get enough B-complexvitamins(found in large
quantities in whole grains)without supplementation.Resources
BOOKS
Sears, Barry.A Week in the Zone. New York: Regan Books,
2004.
Sears, Barry.What to Eat in The Zone: The Quick & Easy,
Mix & Match Counter for Staying in The Zone.
New York: Regan Books, 2004.
Sears, Barry and Lynn Sears.Zone Meals in Seconds: 150
Fast and Delicious Recipes for Breakfast, Lunch, and
Dinner. New York: Regan Books, 2004
PERIODICALS
Cheuvront, Samuel N. ‘‘The Zone Diet Phenomenon: A
Closer Look at the Science Behind the Claims.’’Journal
of the American College of Nutrition. 22, no. 9 (2003):
9-17<http://www.jacn.org/cgi/content/full/22/1/9>
ORGANIZATIONS
American Dietetic Association. 120 South Riverside Plaza,
Suite 2000, Chicago, Illinois 60606-6995. Telephone:
(800) 877-1600. Website:<http://www.eatright.org>
DrSears.Com Official Zone Web Page. Website:<http://
http://www.drsears.com/>
OTHER
Whfoods.org. ‘‘The Zone Diet.’’ World’s Healthiest Foods,
undated, accessed April 22, 2007.<http://www.
whfoods.com/>.
‘‘Frequently Asked Questions—The Zone Diet.’’ ZoneDiet
Info.com undated, accessed April 10, 2007.<http://
http://www.zonedietinfo.com/zone-diet.htm>QUESTIONS TO ASK THE
DOCTOR Do I have any special dietary needs that this diet
might not meet?
Should I take dietary supplements while on this
diet? If so, which ones?
Is it safe to stay on this diet for a long time?
Can everyone in my family go on this diet?
Is there a less complex or less expensive diet that
would meet my needs?
Are the percent of body fat targets this diet sets
realistic for me?Zone diet