Fasting

During a fast, an individual purposely abstains from food for a specific period of time. Fasting has been practiced—for both religious and therapeutic purposes—throughout the ages. A one-day fast is unlikely to cause any harm to a healthy body. Slightly longer fasts (two to three days) are also well tolerated by most healthy people. It is unwise and potentially dangerous for certain groups of people to engage in fasts, no matter how short the duration. These groups include pregnant and lactating women, diabetics, those with cancer, gout, stomach ulcers, liver, kidney, heart, or lung disease, or anyone with a compromised immune system. Most health experts caution against fasts lasting more than two to three days, even for healthy individuals—but if longer fasts are practiced, they should be medically supervised.

During the first twenty-four hours of a fast, the body is able to utilize stored carbohydrates, in the form of glycogen, to fuel essential body processes. When glycogen reserves are depleted, fat becomes the preferred energy source, so that protein is partially spared. Unfortunately, protein is never completely spared and some muscle tissue is lost, even during short fasts. Weakness, nausea, and depression can also develop during a fast, as a result of ammonia and nitrogen released into the blood during the breakdown of muscle. In extreme cases, extended fasts can lead to disturbances of heart rhythm and death. Plenty of water (or other fluids) should always be consumed during a fast.

Fasting should never be used as a weight loss aid. The few pounds that are lost in the beginning of a fast are from water, and this weight will return as soon as the fast is over. Some people fast as part of a detoxification program. However, the value of fasting for this purpose is not yet backed by much scientific research.

“Modified” fasts, in which fruit and vegetable juices are consumed, are probably gentler on the body. Even so, a modified fast should be limited to no more than a few days.

 

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The information presented in HealthNotes Online is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over-the-counter medication is also available. Consult your physician, nutritionally-oriented health care practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.