The Rejuvenative Power of Fasting:
A Complete Guide to Juice and Water Fasting For Better Health


water-fasting-cleansing-the-body-girl-oceanundertaking a short to medium length juice or water fast is one of the fastest and most powerful ways to heal the body of illness, lay a foundation for lifelong health and literally regenerate the body from the inside out.

A great many amazing things happen in the body during fasting. The body, as I have said, has its own wisdom—and it knows a lot about fasting. We are evolutionarily designed to fast, and the body knows how to do it very well.

Fasting allows the body to rest, to detoxify, and to heal. During this time, the body moves into the same kind of detoxification cycle that it normally enters during sleep. It uses its energy during a fast not for digesting food but for cleansing the body of accumulated toxins and healing any parts of it that are ill. As a juice or water fast progresses, the body consumes everything it can that is not essential to bodily functioning. This includes bacteria, viruses, fibroid tumors, waste products in the blood, any buildup around the joints, and stored fat. The result is that the body eliminates its toxin accumulation, just as during a fast the emotional and spiritual bodies eliminate theirs. And although water fasting has always been concerned with both spiritual and emotional healing, it has, as well, been recognized for millennia as one of the most powerful forms of healing for the body.

The physical dynamics that occur during juice and water fasting are complex, and to understand them it helps to understand the process that your body goes through while fasting. The information on physiological changes that are discussed in this article, however, primarily pertains to water fasts. Juice fasting initiates similar but milder changes; the movement into ketosis, for example, is only partial during a juice fast.

Detoxification of the Body

All of us are historically unique in that most of us have developed in a constant bath of synthetic chemicals. This is a unique evolutionary event—we are, in fact, guinea pigs in a vast uncontrolled experiment. This puts unusual strains on us and our bodies that are unique in evolutionary history. All of our bodies must somehow find a way to detoxify not only the toxins that humans have encountered throughout their evolutionary development but also these historically unique synthetic chemicals. In general, juice and water fasting enhances the body’s ability to detoxify toxins—even these unique synthetic compounds—and regenerate any tissues that have been damaged.

There are four primary sources of toxins that people are usually exposed to:

1. Airborne pollution that we breathe in or absorb through our skin
2. Pollutants we ingest on or in our foods
3. Pharmaceuticals
4. Toxins from bacteria and viruses, including those normally in our intestinal tract.

Pollutants that are in or on our foods include such things as synthetic fertilizers, pesticides, growth hormones, and so on that are sprayed on, planted with, injected into, or fed to our plant and animal foods—all of which can be removed from the body with fasting.

Pharmaceuticals are a major source of toxins that people ingest, sometimes daily for many years. These substances are not evolutionarily natural to the human body. That is, the human species has not encountered these particular chemical structures during its long evolutionary history and has no experience in how to deal with them. They must then be excreted, deactivated, destructured, or stored—the most efficient way to do so being water fasting.

All these toxins affect health by disturbing healthy cell function. Detoxification processes such as water or juice fasting allow the body to focus not only on restoring healthy organ function but also on attending to the needs of individual cells. Fasting rests the immune system, the detoxification systems of the body, and the entire digestive system. Instead of these systems analyzing, breaking down, and transporting the thousands of chemicals coming into us from our diets or dealing with the chemicals that come into us from our daily immersion in a technological culture, fasting allows them to rest, retreat, recuperate. Refraining from eating allows the body, just as it allows the spiritual and emotional body, to step back from its constant immersion in life and readjust its relationship with itself, the substances it has taken inside itself over the years, and the environment in which it lives. Deep juice and water fasting puts the body into a state that is normally only experienced during sleep, one in which the liver and other detoxification systems can focus exclusively on detoxification, repair, and regeneration.


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The liver’s cytochrome P450 enzyme system is a unique system that is highly stimulated by fasting; its focus is the removal, deactivation, or reuse of toxic substances within the body. This system of liver enzymes is specifically designed to make unwanted molecules easier to handle, each specializing in a different kind of toxin.

A number of studies have been conducted on what the body does during the deep cleansing that happens while fasting; the results are highly intriguing.

The Physiological Changes of the Body

Many of the most dramatic changes that occur in the body during juice and water fasting take place on the first three days of the fast. These occur as the body switches from one fuel source to another. Normally, the primary form of energy that the body uses is glucose, a type of sugar. Most of this is extracted or converted from the food we eat. Throughout the day, the liver stores excess sugar in a special form called glycogen that it can call on as energy levels fall between meals. There is enough of this sugar source for 8 to 12 hours of energy, and usually it is completely exhausted within the first 24 hours of fasting. Once the liver’s stores of glycogen are gone, the body begins to shift over to what is called ketosis, or ketone production—the use of fatty acids as fuel instead of glucose. This shift generally begins on the second day of water and juice fasting and is completed by the third.

By the third day, ketone production is sufficient to provide nearly all the energy the body needs, and the body’s protein begins to be strongly conserved. Over a 30-day water fast, a person generally loses a maximum of 1 to 2 pounds of muscle mass. This conservation of the body’s protein is an evolutionary development that exists to protect muscle tissue and vital organs from damage during periods of insufficient food availability.

The 7-day period after the body has completely shifted over to ketosis, is where the maximum breakdown of fat tissue occurs. As part of protein conservation, the body also begins seeking out all non-body protein sources of fuel: nonessential cellular masses such as fibroid tumors and degenerative tissues, bacteria, viruses, or any other compounds in the body that can be used for fuel. This is part of the reason that juice and particularly water fasting produces the kind of health effects it does. In addition, during this period of heightened ketosis the body is in a state similar to that of sleep—a rest and detoxification cycle. It begins to focus on the removal of toxins and the healing and regeneration of damaged tissues and organs.

As these fat stores are broken down over the course of the fast, the chemical toxins within the fats are released. Each of these different toxins will have different effects on how you feel. (In addition, the associated emotions or reasons you accumulated that particular fat will also be released.)

Effects on the Brain and Mind

On the third day, when the body has shifted over to ketosis as a primary source of fuel, the brain begins to have enough fuel but it is a different fuel. How you feel and how your brain works on that fuel are markedly different. This is not because the fuel is inferior to glucose—the body can use either fuel with great efficiency. The difference is felt because it has been so long since you and your brain have used this fuel to function. It is more an outgrowth of habituation to glucose than anything else. When in full ketosis, the mind simply works somewhat differently. Thinking can be just as acute, but it tends to be slower, more reflective, more studied and deeper, and—aside from thoughts of food or ending the fast—less inclined to dwell on future plans.

Some researchers’ findings indicate that ketone bodies may actually be the body’s preferred fuel. Studies have shown that they stimulate the heart, adrenal cortex, skeletal musculature, and the brain to better functioning than glucose. The brain’s periodic utilization of this alternative fuel during periods of food shortages also seems to have long-term beneficial effects on brain and central nervous system function. Electroencephalograph (EEG) data and endocrine testing generally show significant improvements after both juice fasting and water fasting.

The body is evolutionarily designed to protect its muscle tissue (of which many major organs, most notably the heart, are composed) from deterioration during long fasts by having an equal ability to utilize ketones for fuel during long periods of reduced food availability.

People Who Should Not Fast

Although most people can fast, there are a few who, because of special conditions, should not.

+ People who are extremely emaciated or in a state of starvation
+ Those who are anorexic or bulemic
+ Pregnant, diabetic women
+ Nursing mothers
+ Those who have severe anemia
+ Those with an extreme fear of fasting
+ Those with porphyria.
+ People with a rare, genetic, fatty acid deficiency that prevents proper ketosis from occurring.

How to Choose Your Type of Fast

When you decide you are ready to fast, think about what kind of fast you want to do. Know also that the older you are, the more intense a fast can be, especially if you have been living a toxic lifestyle for a very long time. If you have never fasted before or if it has been a very long time since you have fasted, you should consider a juice fast. While a juice fast will, like a water fast, bring many benefits and will evoke many deep emotional, spiritual, and physical insights, it is much easier. A juice fast is the best way to first experience fasting.

If you have fasted before or if you are working with an experienced fasting coach or health practitioner, then perhaps you will want to do a deep water fast. A water fast will be much more demanding; the degree of emotional, physical, and spiritual intensity is much higher. The benefits are correspondingly greater, but only if you are ready for it, and are not forcing yourself into it too quickly. Neither fast is better or worse than the other, they just do different things. Each type of fast will make different demands on you; both are of great benefit.

Timing and Length Guidelines

Recommended Schedule for Water Fasting Diet

Phase 0: Regular Diet

Phase 1: 2 weeks (minimum) low-fat cleansing diet

Phase 2: 3 days fresh juices and herbal teas only

Phase 3: 4–10 days water only

Phase 4: 1–3 days fresh fruit juices; miso soup; mild, heavily steamed vegetables

Phase 5: 4–14 days low-fat cleansing diet

Return to Normal: Regular diet

The length of time spent on each of these sections preparing and recovering from water fasting depends on a person’s physical, emotional, and spiritual condition and needs. Important Note: For every day of a water fast, there should be one day of recovery. If you spend 10 days on a water fast, you should spend at least 10 days recovering before engaging in intensive activity.

Recommended Schedule for Juice Fasting Diet

Phase 0: Regular Diet

Phase 1: 2 weeks (minimum) low-fat cleansing diet

Phase 2: 4–30 days fresh juices and herbal teas only

Phase 3: 1 day miso soup and mild, heavily steamed vegetables

Phase 4: 4–14 days low-fat cleansing diet

Return to Normal: Regular diet

As mentioned, the length of time spent on each of these sections depends on a person’s physical, emotional, and spiritual condition and needs.

What to Drink During Your Juice Or Water Fast

Important: If you are conducting your own fast, it is extremely important to obtain good water and/or good foods to juice and drink during your fast.

Make sure you use only healthy spring water for your fast. Do not use distilled water. Distilled water has been technologically altered, and many if not most of the minerals and nutrients have been removed. Do not use tap water. Use the healthiest, wildest, most natural water you can during your cleanse for maximum benefits.

Again, if you are juicing on this fast, obtain only organic vegetables and fruits. Pick them out yourself from a market that feels good and nurturing to you, and choose the ones that seem most alive and healthy to you to consumer during the cleanse.

Returning to Normal After Your Deep Cleanse

Make sure that your reintegration is slow, thoughtful, and cognizant of your increased sensitivities. If your juice or water fast has been a long one, make sure that you have at least 4 days, preferably a week, to reintegrate. Remember, you will need one day for each day you fasted to recover.

If you have deep fasted at home, make sure that you will not be disturbed as you begin breaking the fast. If you have done a deep fast of 7 days or less, make sure that nothing needs your attention for at least 2 days—at least 4 days if the fast was longer.

Reintegrate into food by reversing the eating patterns/phases you used in preparing for the fast. Concentrate on juices and miso soups for at least 3 days. Slowly work back into a low-fat diet. Do not eat meat for at least 1 week.

When you are finished with the period of time you set aside for fasting and are ready to take food into your body again, it is most important to do so with great awareness. Make sure the foods you begin eating—spiritual, emotional, physical—are nurturing foods, and take them in slowly so that you can get used to them once again.

Remember: your entire digestive system has stopped its normal functioning during a water or juice fast. It is in a state of hibernation; it is turned off. It needs mild foods at first so that it can slowly come back on-line again. As you take in miso soup or freshly squeezed orange juice, the body and the digestive system begin to wake up again. Digestive enzymes once again start to be produced, and the whole physiology of the body begins to shift from ketosis back to glucose metabolism. Your brain begins to use a different food once more. All your body systems begin to shift in their orientation and performance. Allow them, and you, to take all the time necessary to make this change. Break the fast with very good food. Slowly.

The more you allow your body to set the pace, the more healthy it will be and the more healthy your daily relationship with food will be. At this time you will notice an extreme sensitivity to food. Your vomeronasal organ will be exquisitely sensitive to the chemicals it encounters. You will be extremely sensitive to its messages. Your cells and organs will want particular food, unique to you, and if you listen carefully you will be able to determine just what you do want and what you do not. Let the wisdom of your body begin to guide you; trust it. In any event, you should not eat heavy foods on finishing a juice or water fast. Your digestive system, your entire body, is not ready to process that kind of food. The body needs at least 3 days to shift over to regular food intake, and even then the amounts desired and needed are usually tiny in comparison to your former meal intake.

This article on juice and water fasting is excerpted with permission from The Transformational Power of Fasting: The Way to Spiritual, Physical, and Emotional Rejuvenation by Stephen Harrod Buhner.

About The Author

Stephen Harrod Buhner is an Earth poet and the award-winning author of twenty books on nature, indigenous cultures, the environment, and herbal medicine. Stephen’s work has appeared or been profiled in publications throughout North America and Europe including Common Boundary, Apotheosis, Shaman’s Drum, The New York Times, CNN, and Good Morning America. Stephen lectures yearly throughout the United States on herbal medicine, the sacredness of plants, the intelligence of Nature, and the states of mind necessary for successful habitation of Earth. Visit his website at