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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 purposes, disagrees.

"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 night."

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 for centuries.

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.

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