High Protein, Low Carbohydrate Diets
High protein, low carbohydrate diets have been widely promoted in
recent years as an effective approach to losing weight.
These diets generally recommend dieters receive 30% to
50% of their total calories from protein . By
comparison, the American Heart Association, the National
Cholesterol Education Program and the American
Cancer Society all recommend a diet in which only
10% to 15% of calories are derived from protein
(nutrients essential to the building, maintenance and
repair of tissues in the body).
The Atkins diet is an example of a high protein, low
How Do These Diets Work?
By restricting carbohydrates drastically to a mere
fraction of that found in the typical American diet, the
body goes into a different metabolic state called
ketosis, whereby it
burns its own fat for fuel. Normally the body burns
carbohydrates for fuel -- this is the main source of
fuel for your brain, heart and many other organs. A
person in ketosis is getting energy from ketones,
little carbon fragments that are the fuel created by the
breakdown of fat stores. When the body is in ketosis,
you tend to feel less hungry, and thus you're likely to
eat less than you might otherwise. However, ketosis can
also cause health problems, such as
kidney failure (see below).
As a result, your body changes from a
carbohydrate-burning engine into a fat-burning engine.
So instead of relying on the carbohydrate-rich items you
might typically consume for energy, and leaving your fat
stores just where they were before (alas, the hips,
belly, and thighs), your fat stores become a primary
energy source. The purported result. weight loss.
What Are the Health Risks Associated With High
Protein, Low Carb Diets?
High protein diets can cause a number of health
Kidney failure. Consuming too much protein
puts a strain on the kidneys, which can make a person
susceptible to kidney disease.
High cholesterol. It is well known that high
protein diets (consisting of red meat, whole dairy
products, and other high fat foods) are linked to high
cholesterol. Studies have linked high cholesterol levels
to an increased risk of developing heart disease and
Osteoporosis and kidney stones. High protein
diets have also been shown to cause people to excrete
more calcium than normal through their urine. Over a
prolonged period of time, this can increase a person's
risk of osteoporosis and kidney stones.
Cancer. One of the reasons high protein diets
increase the risks of certain health problems is because
of the avoidance of carbohydrate-containing foods and
the vitamins, minerals,
fiber and anti-oxidants they contain. It is
therefore important to obtain your protein from a diet
rich in whole grains, fruits and vegetables. Not only
are your needs for protein being met, but you are also
helping to reduce your risk of developing cancer.
Unhealthy metabolic state (ketosis). Low carb
diets can cause your body to go into a dangerous
metabolic state called ketosis since your body burns fat
glucose for energy. During ketosis, the body forms
substances known as ketones, which can cause organs to
fail and result in gout, kidney stones, or kidney
failure. Ketones can also dull a person's appetite,
cause nausea and
bad breath. Ketosis is prevented by eating at least
100 grams of carbohydrates a day.
Is This Diet Right for Me?
These theories of weight loss remain unproven, and
most experts are concerned that high-protein, low carb
diets can cause a host of problems, particularly for the
large segment of the population that is at risk for
heart disease. What's more, the plan doesn't permit a
high intake of fruits and vegetables, recommended by
nutrition experts because of the numerous documented
health benefits from these foods.
The experts say to achieve permanent weight loss you
must change your lifestyle. This means following a lower
calorie diet that includes grains, legumes, fruits and
vegetables combined with participating in regular
Before starting this or any diet, be sure to talk
with your doctor to determine what approach is right for
Reviewed by the Department of Nutrition Therapy at The Cleveland Clinic.
Edited by Charlotte Grayson, MD
, WebMD, August 2004.
Portions of this page © The Cleveland Clinic
2000-2004Last Editorial Review: 7/14/2005