Many cultures around the world practice what they call water fasting. Nowadays, water fasting has become the ultimate weight loss and detox trend. We constantly see people and doctors talking about it and their experience with this growing trend. But the question is – Is water fasting beneficial for our health? If so, what benefits can we expect? And what about potential health issues – Are there any to be expected? You will find the answers to these and many other questions in the following article.  

What is Water Fasting?

Water fasting, as the term implies, is a fast that restricts the intake of all food and drinks except water. It may sound difficult and that is because it is. Water fasting is not for everyone. 

A fast of this kind typically lasts anywhere between 24-72 hours. It can be done at home as well as in a medical institution. Because of the negative effects that it can have, water fasting is not recommended to last longer than 72 hours when done at home. On the other hand, is a medical institution, this fast can take up to 40 days under medical supervision. Water fasting is also not recommended to be done more than twice a month (1).

Now, you may wonder why would one restrict themselves from all foods and drinks other than water. Over the years, there have been many different reasons as to why one would water fast. Up to this day, the main reason remains to be improving one’s health. We will, of course, discuss the potential health benefits that water fasting has to offer. 

Other reasons include weight loss, detox, religious reasons, and as a way to prepare for a medical procedure. Water fasting is a popular method in the wellness movement. Many pair up regular water fasting along with meditation and yoga to take better care of their bodies. Whatever your reason may be, we want to remind you to do it safely and take good care of your overall health.

How to Water Fast Properly?

If this is your first-time water fasting, it is a good idea to start preparing your body for what is to come. We recommend taking as much as 3-4 days preparing. Focus on eating 3-4 smaller meals throughout the day. 

Another great way to prepare is by fasting for a few hours a day. You can practice the 16:8 fast which is when you eat for 8 hours a day and fast the remaining 16 hours. During this fast, although all foods are restricted, you can enjoy some calorie-free drinks such as unsweetened tea, coffee, and water. 

Once you start your water fasting, focus on drinking as much as two to three liters of water per day. As we mentioned earlier, do not extend your water fasting beyond the recommended 72 hours to avoid any health risks. Do ask for medical help in case of any health concern. Some speak of experiencing dizziness and weakness during the fast (2). If this happens to you, avoid operating any heavy machinery and driving to avoid any accidents. 

Understandably, as soon as your fast ends, you will feel an urge to eat a large meal. This, however, is something that you would want to avoid. Similarly, as to how you take a few days preparing before your fast starts, you will also need to spend a few days getting used to getting back on track with your normal eating habits. 

The duration of the post-fast phase depends on the duration of the fast itself. The shorter your fast is, the shorter your post-fast phase will be too. Those who have been fasting for up to 3 days would need to take 3 days to get back to eating normal meals. Take it slow in order to prevent the risk of refeeding syndrome, especially after long fasts. The refeeding syndrome is a potentially life-threatening condition that causes rapid changes in the body’s fluid and electrolyte levels (3).

Start your post-fast phase by preparing yourself a nutritional smoothie. From there on, focus on eating a couple of small, nutrient-rich meals throughout the next couple of days. Avoid eating any empty calories, fast food, and drinking alcohol for the time being. After the post-fast phase, you are expected to go back to your normal eating habits. 

What Are the Potential Health Benefits of Water Fasting?

1. Lower Blood Pressure Levels

Water fasting is said to help normalize the blood pressure levels among those with hypertension or high blood pressure. For this effect to occur, however, a longer, medically-supervised water fasting needs to take place. 

A 2002 study showed that water fasting has helped normalize borderline hypertension. A total of 68 patients with borderline hypertension took place as a part of the study. After 14 days of medically-supervised water fasting, up to 82% of the participants experienced their blood pressure levels falling back within normal ranges (4). Another study showed similar results but with a shorter duration of the fast itself (5).

Up to this day, however, there are no studies that investigate the link between short-term water fasting and blood pressure levels. If you are someone who struggles with hypertension, we urge you to ask for medical help before trying out short- or long-term water fasting. 

2. Improved Insulin and Leptin Sensitivity

Diabetes patients may also benefit from medically-supervised water fasting. Insulin and leptin are two very important hormones in our body. Both affect the metabolism in two very different ways. While insulin helps with the nutrients storage, leptin lets our brain know when we are full and done eating. Science shows that water fasting could improve both our insulin and leptin sensitivity, thus making them more effective (6, 7).

Having a higher insulin sensitivity will make it less likely that you experience diabetes since your body will become better at reducing its blood sugar levels. On the other hand, better leptin sensitivity translates to lower obesity risk (8, 9, 10). Other than diabetes, obesity also increases the risk of heart disease, metabolic syndrome, arthritis, and many other chronic conditions (11). So, you see, water fasting could shield you from many problems at once. 

3. Possible Autophagy

For those of you unfamiliar with autophagy, think of this as your cell recycling. What happens is the body breaking down its old cells (12). Over the years, there have been animal studies investigating the potential health benefits of autophagy. And so, research suggests that autophagy may protect us against several types of cancer, heart disease, and even Alzheimer’s disease (13).

While there are no human studies, there are a few animal studies that investigate the link between water fasting and autophagy. The results are quite positive with water fasting efficiently promoting autophagy (14). Besides, some studies speak of a potentially longer life span due to water fasting-induced autophagy in animals. However, because of the lack of human studies on the subject, it is impossible to confirm the health benefits of water fasting-induced autophagy. 

Can You Lose Weight by Water Fasting?

The short answer is yes, it is very likely that water fasting will help you lose weight. Are there other, more effective, and safer weight loss techniques? Yes, there sure are. You see, water fasting, like the other popular fasting methods, can help eliminate those extra body pounds. However, at the same time, you will be paying quite the price in terms of potential health risks and complications. This is why we recommend other weight loss and fasting methods over water fasting for the sole purpose of weight loss.

Is It Safe?

While it is clear that water fasting has certain health benefits, we should not ignore the potential health risks as well. In the following, we will explain the most common health risks that you should keep your eye on while water fasting.

1. Dehydration

This may come as a surprise but water fasting may lead to dehydration. You see, scientists have discovered that up to 20% of our daily water consumption comes from the foods that we are eating (15). That is why you need to increase your water intake during the fast. This is especially important for those of you who do not have the habit to intake enough water during the day. 

2. Nutrient Deficiencies

As healthy as water is, it is still a very poor source of the much-needed vitamins, minerals, electrolytes, amino acids, and the rest of the nutrients that our body needs to function properly. Water fasting exposes you to the potential risk of multiple nutrient deficiencies which is why this method is not recommended for a long period of time. 

3. Hyponatremia

Hyponatremia is more commonly known as water intoxication. This condition takes place once your body is deprived of the salt that it contains through the natural process of sweating. It is then that the salt is replaced by only water. In normal circumstances, you would replace the lost salt through eating food and drinking sports drinks. This, however, is not possible during water fasting. To avoid this, avoid any intense exercise and activities that would cause you to excessively sweat. 

4. Binge Eating

The reason why so many of us struggle with weight loss is due to binge eating. Binge eating is a serious eating disorder that requires professional help. This kind of behavior is usually triggered due to restricting calories and dieting. Unfortunately, fasting, too, can cause binge eating. This is why those that struggle with eating disorders are advised against fasting of any kind, including the popular water fasting. 

5. Blood Pressure Changes

Drinking too little water can lead to dehydration. On the other hand, drinking too much of it may cause hypotension or low blood pressure. Water fasting has led to orthostatic hypotension in the past too. In this case, you experience sudden drops in blood pressure levels upon standing up. 

Orthostatic hypertension may also take place as well which is when a sudden increase in blood pressure levels occurs upon standing. If you experience any blood pressure changes during water fasting it is incredibly important that you consult a doctor. 

Who Should Not Water Fast?

In the beginning, we explained that water fasting is not for everyone and we will explain what we meant by that. For starters, there is the fact that water fasting is not a pleasant experience. Very few of us are used to getting through such long periods of time without any food or drink other than water. Water fasting is not the only way to improve one’s health. If this does not work for you, there are other methods for you to explore. 

There are, however, certain individuals that are strongly advised against water fasting. People in this group should always consult a medical professional before deciding to fast. This list includes:

  • Young adults under the age of 18;
  • Older adults;
  • Pregnant and breastfeeding women;
  • Underweight individuals;
  • Individuals who are using prescription and/or over-the-counter medication;
  • Individuals who are managing an addiction;
  • Individuals with eating disorders;
  • Diabetes patients;
  • Chronic kidney disease patients;
  • GERD (Gastroesophageal reflux disorder) patients;
  • Heart disease patients;
  • Individuals who are experiencing uncontrolled migraines, etc.

What to Expect During the Fast?

Food is what fuels our body with energy daily. Since fasting deprives our body of the fuel that it needs, it is natural that you feel as your energy levels drop, despite getting a good night’s sleep. Food deprivation may also cause the following symptoms and feelings:

  • Weakness;
  • Dizziness;
  • Nausea;
  • Irritability, etc.

If you happen to experience any of these symptoms, it is important that you take the following steps. Make sure that you are getting enough rest and avoid any intense exercise. This will help conserve as much energy as possible. If these symptoms become severe enough, you may need to eat a small meal. Feeling confused and disoriented are signs that you need to ask for medical help. 

Tips on How to Get the Most Out of Your Water Fasting

Now that you have made the ultimate decision regarding water fasting, here are a few useful tips on how to do it right and get the most out of its beneficial effects. Anyone new to the concept of fasting should start small. Start with a one-day water fasting and see how that affects both your physical and mental health. Avoid fasting for longer than three days. 

Take time to prepare for your fast. Start fasting at a convenient time, for example over the weekend. Always avoid fasting if you feel tired or unwell before the fast. Since drinking too much water all at once can be potentially dangerous, make sure that you spread your water intake throughout the day. Stay on track with your daily water intake and refrain from drinking too little or too much water. And last but not least important is keeping an eye on your food intake after your fast has finished. Eating too much can cause some serious aches and issues. To avoid that, carefully plan and spread your meals for the next few days.


Although water fasting sure does offer its share of science-supported health benefits, it may not be the best weight-loss method out there. For health improvement, water fasting is best done under medical supervision over 10-14 days. This, however, may cause some negative effects in the form of weakness, irritability, and tiredness. Other alternatives may be a better fit. 

















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