Just as there are different reasons for fasting, there are several definitions. Fasting is often used as a means of weight loss, detoxification of the body for medical reasons, or as a spiritual practice. Done as a spiritual practice, fasting is defined as abstention from food for the purification of one’s motivation.
Some people balk at juice fasting because it does not include the abstention from food. While this much may be true, juice fasting can have real benefits is practiced correctly.
As the name suggests, juice fasting is the consumption of only juice for a specified amount of time, usually one to 14 days. Juice fasts are sometimes marketed together with supplies, supplements, and support groups. Many of these groups have strict rules as to how the juice fast should be administered. For example, proponents of a raw food diet insist that a juice fast must only contain fresh, juice obtained from organic fruits and vegetables processed through a juicer or juice extractor, and that prepackaged juices cannot be used because they have been pasteurized. Furthermore, the fresh juice must be consumed within a half hour of extraction and cannot be refrigerated. This alone can make juice fasting an arduous task.
Advocates of juice fasting believe that it causes the body to expel the normal byproducts and toxins of metabolism. Some adherents believe that the human body is incapable of processing or excreting these byproducts under normal circumstances and that juice fasting causes this elimination. On this issue, some experts suggest that water-only fasting is superior to juice fasting because it allows the body to rest in a manner than juice fasting does not. According to Naomi Neufeld, an endocrinologist at UCLA, water-only fasting does the following whereas juice fasting does not, “Eventually the body burns up stored sugars, or glycogen, so less insulin is needed to help the body digest food. That gives the pancreas a rest. On juice diets recommended by some spas, you may lose weight, but your digestive system doesn’t get that rest.”
Juice fasting is done at facilities and retreats all over the world. The well-known Buchinger clinics in Germany have conducted supervised juice fasts for 90 years. Although the Buchinger clinics call their method “therapeutic fasting,” this is a misuse of the term since research refers to therapeutic fasting as water-only fasting.
There are few peer-reviewed studies supporting the efficacy of juice fasting. One study of five men found that those who juice fasted had a small improvement in their blood cholesterol levels. Even with this limited evidence, some experts believe it can be useful for some populations. However, others caution that juice fasting can be more harmful than helpful, particularly for people with certain conditions. It is important to note that the same thing can be said about water-only fasting. In fact, juice fasting is contraindicated in the same populations as is water-only fasting, such as young children, pregnant or lactating mothers, and those with liver and kidney problems.
People with a low body weight need to be monitored for protein-calorie malnutrition and other complication. In certain conditions, such as cancer, autoimmune diseases, or other chronic illnesses, the body needs more nutrients than usual and juice fasting could exacerbate illness. People who have diabetes or suffer from glucose problems should not attempt an unsupervised juice fast because the low-calorie intake along with the high intake of sugar found in juice can cause a number of problems.
Another problem that frequently occurs with juice fasting is diarrhea. If diarrhea persists, dehydration occurs due to excessive loss of fluids and electrolytes. When diarrhea is prolonged or severe, deficiencies occur with sodium and potassium, and abnormalities of chloride and bicarbonate also may develop. During water-only fasting, bowel movements generally stop after the first few days.
As with water-only fasting, it is best to be supervised if you are planning your first juice fast. Even if you are only planning a day or two, you would want to get the support of your primary health care provider.