The health benefits and dangers of water fasting with distilled water

Written by William Fryer - MA Oxon

Water fasting with distilled water basically involves consuming only distilled water. This pushes your body into a state of starvation. It is a controversial therapy. Some people are keen advocates but others regard it as unnecessary or potentially dangerous.

Who should avoid water fasting?


Some people should avoid water fasting under any circumstances, this includes children, pregnant and breast-feeding women and people with certain medical problems for example type 1 diabetes. If you are considering a distilled water fast you should consult your doctor first, especially if you have any concerns.

How does water fasting work?

For the first six hours after your last meal, all the remaining glucose, amino acids and fats are absorbed by your body. Over the next two days, you will start to use glycogen (glucose stored in the liver), this energy generation process is called glycogenolysis - this period lasts for 12-24 hours. After this, your body will start to break down fatty acids into ketones - ketosis. These ketones are then used to fuel your body. People in ketosis have a characteristic ketone breath - it smells like pear drops. NB: During this period your body can also break down muscle for energy leading to muscle wasting.

Benefits of water fasting

Water fasting advocates mainly talk about the “detoxification” of the body. The idea is that by consuming only water you will flush all the toxins out of your body. In reality, you are simply pushing your body into starvation mode. This does have one benefit. When you starve for a short period (eg. 1-3 days) your body does release lots of biochemicals which have an antioxidant/rejuvenating effect. This is scientifically well-documented.

Water fasting is also a good way to lose weight (within reason), when your body is in ketosis you are literally burning fat for energy.

However, there are a lot of downsides to water fasting:

If you starve your body for long periods (greater than 3 days) you will start to use muscle for energy, this leads to muscle wasting, not advised. This muscle breakdown as well as causing weakness can also block up your kidneys causing an acute kidney injury. The main treatment for this is flushing with fluids, so anyone on a water fast should drink more water than they normally would – this will help to keep the kidneys clear.

If you starve yourself for 5 or more days you run the risk of getting what is called refeeding syndrome when restarting food. This is where your body actually gets deficiencies of potassium, magnesium and phosphate and other electrolytes potentially leading to seizures, nausea, vomiting, abdominal pain and heart arrhythmias. Refeeding is a medical emergency requiring hospital treatment. The easy way to avoid it is to not starve for more than five days. You can also avoid it by introducing foods slowly, eg start with raw veg and gradually build up the calorific density.

In summary

Water fasting is not for everyone. If you want to try it. Make sure you consult a doctor if you have any reservations, then only do a maximum of five days. 

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