|
Other common name(s):
none
Scientific/medical name(s):
none
Description
Fasting involves not consuming any foods and drinking only
water or juice for 1 to 5 days (or longer). Sometimes, tea or broth may
be part of the fasting process. Fasting is often promoted as part of a
"detoxification" process in metabolic therapies for cancer or other
conditions.
Overview
Available scientific evidence does not support claims that fasting is effective for preventing or treating cancer. Even a short-term fast can have negative health effects, while fasting for a longer time could cause serious health problems.
How is it promoted for use?
Practitioners of alternative metabolic therapies believe the body contains many environmental toxins and other harmful substances that can be removed by fasting or detoxifying the body (see Metabolic
Therapy). They claim that fasting allows the body to focus
energy on cleansing and healing itself. According to these
practitioners, fasting helps the immune system work more efficiently
and allows more oxygen and white blood cells to flow through the body,
more fat to be burned, energy to increase, and other healing functions
to improve. In people with cancer, some claim that fasting can “starve” a tumor, leading to cell death.
Other illnesses and conditions claimed to be treated by
fasting include acne, allergies, arthritis, asthma, non-cancerous
tumors, digestive disorders, fever, headaches, glaucoma, heart disease,
high blood pressure, inflammatory diseases, pain, polyps, and ulcers.
Fasting is also promoted to rejuvenate the body, help maintain normal
body weight, increase longevity and sex drive, and to improve mental
clarity, self-awareness, and self-esteem. It is also said to be helpful
in quitting or cutting back on use of tobacco, alcohol, caffeine, or
non-prescription drugs. Some practitioners claim it can heighten
spiritual awareness.
What does it involve?
Short fasts, lasting from 1 to 5 days, are often done at
home. Other than drinking only water or juice, fasting involves a lot
of rest periods. Sometimes other methods of detoxification, such as
liver flushes or enemas, are recommended as part of the regimen (see
also Juicing,
Liver
Flush,
Colon
Therapy). Longer fasts require professional supervision and
often take place at a spa, resort, or similar facility.
What is the history behind it?
Ancient cultures believed fasting could purify the soul. The
belief that fasting can also purify or cleanse the body is a fairly
modern idea, gaining popularity in the second half of the 20th century.
What is the evidence?
Available medical evidence does not support fasting as a treatment for cancer. Some studies in animals have suggested that long-term calorie restriction -- that is, consuming fewer than normal amounts of calories each day -- may slow the growth of certain tumors, but this is not the same as fasting. In fact, some animal studies have found that fasting (no food for several days) could actually promote some tumors. No human studies on the effects of fasting on cancer have been published in the available medical literature.
A brief fast (usually 8 to 12 hours) is often advised by medical professionals in preparation for certain diagnostic tests. In this case, the fast helps to produce more accurate test results. Fasting may also be advised for a period of time before and after surgery, especially if digestive system organs are involved. This is mainly to ensure the stomach and bowels are empty during surgery. This is intended to avoid getting stomach contents into the lungs, since anesthesia disables the usual protections such as swallowing and coughing that work when a person is awake. It also allows the intestines time to recover from anesthesia before re-introducing food.
As for maintaining proper weight, most experts recommend a combination of limiting portion sizes, choosing healthful foods, and being physically active instead of fasting.
Some research has suggested that short-term fasts may briefly improve the symptoms of rheumatoid arthritis. However, the benefits do not last longer than 10 days, and fasting is not a recommended component of arthritis care.
Are there any possible problems
or complications?
Fasting can have short-term side effects such as headaches,
dizziness, fatigue, abnormal heart rhythms, and a fruity taste in the
mouth. It can also raise the risk of an attack in people with gout.
Longer-term fasting can interfere with the immune system and vital
bodily functions, and can damage the liver, kidneys, and other organs.
Fasting can be especially dangerous in people who are already
malnourished, such as those with some forms of advanced cancer.
Women who are pregnant or breast-feeding should not fast.
Relying on this type of treatment alone, and avoiding or delaying conventional medical care, may have serious health consequences.
Additional Resources
More Information From Your
American Cancer Society
The following information on complementary and alternative
therapies may also be helpful to you. These materials may be ordered
from our toll-free number (1-800-ACS-2345).
References
Caderni G, Perrelli MG, Cecchini F, Tessitore L. Enhanced
growth of colorectal aberrant crypt foci in fasted/refed rats involves
changes in TGFbeta1 and p21CIP expressions. Carcinogenesis.
2002;23:323-327.
Cassileth B. The Alternative Medicine Handbook.
New York: W. W. Norton & Co; 1998.
Hikita H, Nuwaysir EF, Vaughan J, et al. The effect of
short-term fasting, phenobarbital and refeeding on apoptotic loss, cell
replication and gene expression in rat liver during the promotion
stage. Carcinogenesis. 1998;19:1417-1425.
Hikita H, Vaughan J, Pitot HC. The effect of two periods of
short-term fasting during the promotion stage of hepatocarcinogenesis
in rats: the role of apoptosis and cell proliferation. Carcinogenesis.
1997;18:159-166.
Legro RS, Finegood D, Dunaif A. A fasting glucose to insulin
ratio is a useful measure of insulin sensitivity in women with
polycystic ovary syndrome. J Clin Endocrinol Metab.
1998;83:2694-2698.
PDRhealth. Detoxification therapy. 2004. Available at:
www.pdrhealth.com/content/natural_medicine/chapters/201160.shtml.
Accessed August 4, 2005.
PDRhealth. Fasting. 2004. Available at:
www.pdrhealth.com/content/natural_medicine/chapters/201200.shtml.
Accessed August 4, 2005.
Sesca E, Premoselli F, Binasco V, Bollito E, Tessitore L.
Fasting-refeeding stimulates the development of mammary tumors induced
by 7,12-dimethylbenz[a]anthracene. Nutr Cancer.
1998;30:L25-30.
Note: This information may not
cover all possible claims, uses, actions, precautions, side effects or
interactions. It is not intended as medical advice, and should not be
relied upon as a substitute for consultation with your doctor, who is
familiar with your medical situation.
Revised: 07/12/2007
|
