Is Fasting Healthy?
Fasting has been practiced for centuries. But can it really help you lose weight and get healthier?
Does Fasting Detoxify the Body?
Here's where the debate gets intense.
"There is no scientific evidence it will detox the body. The issue of
fasting to cleanse the body has no biological basis because the body is real
good at that by itself," says Fernstrom. "The liver is a natural detox
center; the lungs, the colon, the kidneys, [the lymph glands] and the skin get rid of toxins."
But Fuhrman, who has supervised hundreds of patients' fasts for medicinal
"We know that the body is unable to rid itself of toxins when we eat a
diet low in nutrients," and that applies to most Americans, even those who
think they are healthy, he says.
"Americans eat 51% of their diet from processed foods and foods low in
phytochemicals and antioxidants," he says. "So you see a buildup of
waste products in the cells -- AGE, advanced glycation end products -- that
build up in cellular tissues and lead to atherosclerosis, aging, diabetes, nerve damage, and the
deterioration of organs. This is basic science and physiology every doctor
learns in medical school."
Along with improving your overall diet, fasting is one solution to that
buildup of AGE, according to advocates like Fuhrman.
"Fasting allows the body to most effectively remove these waste
products," he says. "The body is designed to fast; we do it every
How does fasting remove toxins from the body? When you go without eating for
more than a day or two, the body enters into ketosis. Ketosis occurs when the
body runs out of carbohydrates to burn for energy, so it burns fat.
"And the fat is where the body stores many of the toxins it absorbs from
the environment," Fuhrman says.
Spiritual and Religious Fasting
Whether fasting can help rid the body of waste buildup is a matter of
controversy. But fasting has been used for religious and spiritual purification
Nearly every religious text you can name, from the Old and New Testaments of
the Bible to the Quran and the Upanishads, calls upon followers to fast
periodically as a rite of spiritual purification, penitence, or preparation for
union with God.
Medical Reasons for Fasting
Another topic on which there is medical agreement is the benefit - actually,
the necessity -- of fasting before surgery.
"You don't want the body to be digesting food as it manages the slower
breathing [and other body changes] under anesthesia," says Fernstrom.
Fasting is also required to get accurate readings for certain medical tests.
Short-term fasting before tests for cholesterol and blood sugar
levels, for example, helps achieve a more accurate baseline count.
Fasting to Treat Disease
Fasting advocates also claim that the practice can effectively treat serious
health conditions, from arthritis and colitis to heart disease and depression.