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Fast One Week Diet

By Linda Tarr Kent ; Updated July 18, 2017

Some diets are based solely on fasting, while others incorporate it into a larger plan. One plan recommends that you fast for one week twice each year. There are safety concerns associated with this diet, especially if you have a health condition. Always consult a health-care provider before trying a new diet plan or before fasting.


The theory behind fasting is that it detoxifies your body. That means it gets rid of toxins from the environment such as pesticides or cigarette smoke as well as things you may have ingested, such as antibiotics or other drugs. Some people say the process also leads to spiritual enlightenment and improved motivation to stay on a healthy eating and exercise plan.

Time Frame

There are three phases you’ll follow for your one-week fast. During the pre-fast phase you eat an abundance of fiber-rich foods, cut out protein and fat and drink large quantities of juice and water. This lasts three days. The second phase is five days. You consume vegetable juice and limited fruit juices. During the final phase you slowly re-introduce foods, starting with non-starchy vegetables. You then can add grains and starchy veggies followed by legumes, nuts and fats, according to the Diets In Review website. Organic foods are required for this diet plan.


This diet has several disadvantages. For example, it requires a daily enema, according to the Diet Spotlight website. It also causes you to have a very low caloric intake and may lead to nutritional deficiencies. Following it may also cause constipation, note the experts at Diets In Review. You may suffer side effects from fasting, as well. These include muscle aches, nausea, dizziness and headaches, according to Vanderbilt University in Tennessee. Less common side effects can include emotional distress, a drop in blood pressure and a persistent cold.


The creators of the fasting diet do promote exercising while on your fast. While you are advised to follow your regular routine, it may be difficult to perform strenuous exercise due to the low caloric intake, according to Diet Spotlight. You also may lack energy for other daily activities, according to Diets In Review.

Expert Insight

According to the Mayo Clinic, there's little evidence that detox diets actually work. Most of the toxins you ingest are effectively removed by your liver and kidneys anyway, then excreted in stool and urine. Side effects from fasting can include dizziness, nausea, fatigue and dehydration, according to the Mayo Clinic.


You need to avoid fasting if you are already suffering from fatigue or a fever because you need nourishment rather than food deprivation, according to Vanderbilt University. If you have a life-threatening condition such as cancer, you also need to avoid fasting, especially if you already are emaciated. If you have diabetes, fasting is not recommended, and you must do so under a doctor’s supervision if you decide to try it. If you have kidney failure, liver problems, anemia, are pregnant or take prescription medicine, you should not fast.

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