alcohol
diet soft drinks
Getting the protein :carbohydrate:fat proportions
right requires a good bit of measuring and calculating,
which can, at least at first, be time consuming and
confusing. Zone participants are also instructed to
do the following:
Eat three meals and two snacks daily, all of which
meet the 40:30:30 ration of carbohydrates to proteins
to fats.
Eat the first meal of the day within one hour of
arising.
Never allow more than five hours to pass without
eating.
Drink more than 8 cups (64 oz or almost 2 L) of
water daily.
Exercise moderately every day.
Meditate daily.Function
The science behind the Zone diet can be quite
complicated and intimidating to someone not trained
in biochemistry or nutrition. The explanation Sears
gives of why the Zone diet works is based on an inter-
play of foods, the hormones insulin and glucagon, and
hormone-like substances called eicosanoids.
The simplified explanation goes like this. When
people eat, the level of glucose (sugar) in their blood
increases. How much it increases depends on the foods
they eat. ‘‘Good’’ foods with a low glycemic index
(below 50) raise blood sugar less quickly than ‘‘bad’’
foods with a high glycemic index (above 65). When
blood glucose levels increase, cells in the pancreas
release the hormone insulin. This signals cells to con-
vert glucose into a compound called glycogen that is
stored in the liver and muscles and facilitates the stor-
age of fat, stored in fat cells. When blood glucose levels
go down, different cells in the pancreas release the
hormone glucagon. Glucagon signals cells in the liver
and muscle to release glycogen, which is converted
back into glucose and is burned by the body. If glucose
levels continue to be low, fat is also burned for energy.
According to Sears, carbohydrates, especially
those with a high glycemic index (e.g. bread, cereal,
sweets), cause the pancreas to release a lot of insulin,
which in turn causes the body to store a lot of glyco-
gen. Proteins, on the other hand, stimulate the body to
release glucagon and burn stored glycogen, so that the
body uses more calories.
Sears also says that another group of hormone-
like compounds called eicosanoids comes into thefood-insulin-glucose-glycogen equation. Eicosanoids
are hormone-like substances that affect the immune
system, nervous system, and cardiovascular system.
‘‘Good’’ eicosanoids reduce inflammation (irritation)
in the walls of the blood vessels and help keep blood
cells from clotting. This helps blood vessels stay open
and prevents stroke and heart attack. ‘‘Bad’’ eicosa-
noids do the opposite. They cause inflammation and
help blood to clot. Sears believes that increasing the
amount of ‘‘good’’ eicosanoids to improve health can
be done by following his diet. His books give a more
complex explanation of the biochemistry involved in
the process of regulating ‘‘good’’ and ‘‘bad’’ eicosa-
noids. Ultimately, he says that staying ‘‘in the Zone’’
by eating foods in the ideal proportions promotes both
burning fat and cardiovascular health.Benefits
Barry Sears, developer of the Zone diet says that
the makes the following claims for the Zone diet:
weight loss of 1–1.5 lb (.6–.7 kg) per week.
permanent weight loss
improved physical and mental performance.
prevention of chronic cardiovascular diseases
improved immune system functioning
decreased signs of aging and increased longevity
no need to count calories (count Zone Food Blocks
instead)
Many of these benefits are disputed by the dieti-
tians and nutritional research scientists (see below). In
addition, staying on the Zone diet while eating in
restaurants can be quite difficult. Home delivery of
perfectly balanced Zone diet meals and snacks is avail-
able at a price of about $37 per day in 2007.Precautions
People with reduced kidney function should dis-
cuss this diet with their doctor because of the high level
of protein. Severely reducing the amount of grains
eaten, especially whole grains, may lead to not getting
enough dietaryfiber. Dietary fiber plays an important
role in maintaining bowel function. Too little fiber can
result inconstipation.Risks
This diet is unlikely to meet the calorie and nutri-
tional needs of children, pregnant women, orbreastfeed-
ingwomen, even though Sears suggests that pregnant and
breastfeeding women increase their food intake by about
25%. In addition, Sears recommends that people on the
Zone diet take dietary supplements.HespecificallyZone diet