adult’s total daily calories or about .36 g/lb (.8 g/kg) of
ideal body weight is a reasonable amount of protein to
maintain health. By contrast, some of the high protein
diets recommend between 35% (Atkins) and 64%
(Stillman) of daily calories come from protein. This
is equivalent to about 1–2 g/lb (2.2-4.4 g/kg) of ideal
body weight.
Extra amino acids are not stored in the body.
Instead, they are split apart by enzymes, and the part
containing nitrogen is excreted by the kidney in urine,
while the remainder is either converted into glucose (a
simple sugar) and used for energy or stored as glyco-
gen, a compound that can later be reconverted into
glucose.
High protein diets are also high in saturatedfats.
Saturated fats are animal fats. They are considered
‘‘bad’’ fats because they raise the level of LDL choles-
terol (‘‘bad’’ cholesterol) in the blood. High LDL cho-
lesterol levels are associated with an increased the risk
of heart disease. High protein diets also restrict calo-
ries by severely restricting carbohydrates. Whole-
grain carbohydrates are a significant source of B-com-
plexvitamins. There are groups who need extra pro-
tein—rapidly growing adolescents, pregnant and
nursing women, bodybuilders, endurance athletes,
and somecancerpatients— but these groups need to
increase protein as part of a well-balanced diet.
Function
High protein diets do promote fast initial weight
loss, although most of the loss comes from losing
water. The reason for this is that they drive the body
into a state called ketosis. The body prefers to break
down carbohydrates into glucose and use that glucose
for energy. When the body is starved for carbohy-
drates, it begins converting fat into glucose. The proc-
ess of converting fat into glucose releases water
molecules which then leave the body as urine.
Dieters, of course, want to burn fat, but when they
burn fat exclusively, a side effect of this reaction is that
molecules called ketones build up in the blood. If the
body is deprived of carbohydrates for a long time,
these ketones accumulate and cause metabolic imbal-
ances that can seriously harm the kidney and other
organs. Ketones are part of the body’s defense against
starvation. They suppress appetite. They also cause
bad breath.
Benefits
High-protein diets offer fast weight loss. The Still-
man Diet claims an individual can lose up to 30 lb
(13.5 kg) in 28 days. Some high protein diets also claim
health benefits. The Zone diet claims it will improve
physical and mental performance, prevent chronic
cardiovascular diseases, improve immune system
functioning, decrease signs of aging, and increase
longevity.
Rapid weight loss does occur with high protein
diets, but much of the loss comes from losing water.
This weight soon returns when the dieter goes off the
diet. Other health claims have not been proven by any
rigorous, scholarly research studies.Precautions
The risk of kidney damage is greater in individuals
with poor kidney function who choose a high protein
diet. High protein diets put an extra workload on the
kidney because the nitrogen-containing part of excess
amino acids is split off and has to be removed from the
body in urine. Although this is not usually a problem
for healthy kidneys, it can cause more damage in
kidneys whose functioning is already reduced.Risks
Nothing about high protein diets is balanced. Vir-
tually all high protein diets recommend that the dieter
take some sort of vitamin or mineral supplement. By
restricting carbohydrates, these diets reduce the
amount of vitamins, mineral, and dietaryfiber. High
protein diets also increase the amount ofcalcium
excreted by the kidney. This increases the loss of cal-
cium from bone and can lead toosteoporosis. It alsoQUESTIONS TO ASK THE
DOCTOR Is a high protein diet better for me than a regular
calorie-reduced diet?
Does this diet pose any special risks for me that I
should be aware of?
Do I have any special dietary needs that this diet
might not meet?
Do I need to take a dietary supplement while I
am on this diet?
What are my risk factors for cardiovascular
disease and how will this diet affect them?
How long can I stay on this diet?
Do you have any experience with the long-term
success of this diet?
If one of your family members wanted to go on a
diet, would you recommend this one>High-protein diet