Blog Diets Fasting 4 Water Fasting Benefits and What to Expect

4 Water Fasting Benefits and What to Expect

Consuming nothing but water for 24-72 hours sounds daunting, extreme, and downright dangerous. Well, that’s because it is, especially when done without proper guidance and medical supervision.

According to health experts, going through extended periods of water fasting can significantly increase the risk of electrolyte imbalance and dehydration (2).

So, why do people subject themselves to such a regimen? Are there any benefits of undertaking this seemingly harsh practice? There are said to be a few. Proponents argue that water fasting can lead to enhanced physical and mental clarity, improved metabolic health, and even a deeper sense of spiritual awareness.

Here’s what you need to know about the purported benefits of water fasting and what you might realistically expect if you’re considering this practice.

N/B – Proceed with caution, arm yourself with knowledge, and always consult with a healthcare professional before starting any form of fasting.

What Is Water Fasting?

Water fasting is the practice of abstaining from all food and drink except water for a specific period. Some people choose to do it for 24 hours, while others go for several days or even weeks under close medical supervision.

During this time, no calories are consumed, so the body has to rely solely on its energy stores (glycogen and fat) for fuel. In general, the longer the fast, the further into these energy reserves the body will have to delve.

There are many reasons why people undertake water fasts. Some do it for religious or spiritual reasons, others as a way of “detoxing” and “resetting” their bodies, and some to lose weight.

No matter the motivation, it’s essential to understand the potential benefits and risks before embarking on this journey.

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Is Water Fasting Good for The Body?

Water fasting is claimed to have some benefits such as weight loss, enhanced mental clarity, and improved metabolic health. However, its efficacy varies among individuals, and there are surely more sustainable and safer ways to achieve these goals.

See also
Intermittent Fasting Macros – Managing Calories the Smart Way!

Potential Weight Loss

A reduction in your calorie intake, which is inevitable during water fasting, may lead to weight loss. 7 day water fasting may lead to an initial weight loss of a few pounds, but this is usually mostly water weight. As your body is depleted of glycogen stores, the water that was stored with the glycogen will also be released and excreted (15).

The case for 30 day water fasting, or other extreme periods, is more complicated. Since the body needs energy to function properly, it may go into starvation mode and slow down the metabolism in order to conserve energy. This can lead to a decrease in weight loss results over time (14).

You may inevitably lose muscle mass during a long-term water fast, which can in turn slow down your metabolism even further.

Furthermore, any weight lost through such extreme fasting is often quickly regained once normal eating patterns are resumed (14).

Mental Clarity and Focus

When you fast, your body starts to burn fat for energy, producing ketones as a byproduct. One of these ketones, beta-hydroxybutyrate (BHB) (1), can cross the blood-brain barrier and provide an alternative source of energy for brain cells. ALthough glucose is the preferred energy source for the brain, some people feel that, for them, fasting leads to increased mental clarity and focus, as well as a boost in mood (10).

Fasting can stimulate the production of certain neurotransmitters and neuropeptides, which may explain why some people experience mood enhancement (10).

Please note that while these mechanisms are supported by some research, more studies are needed to fully understand the effects of fasting on cognitive function.

See also
Intermittent Fasting and Running: A Winning Combination or a Terrible Mistake? 

water fasting benefits  

Metabolic Health

Water fasting has been linked with improved insulin sensitivity and lower blood sugar levels (11).

Hormones like insulin and cortisol, which regulate metabolism, are affected by prolonged periods of fasting. As a result, some people may see improvements in certain metabolic markers such as cholesterol levels and blood pressure, although other markers are sometimes seen to worsen (11).

However, these benefits are not exclusive to water fasting and can also be achieved through other forms of calorie restriction or a healthy diet and exercise routine.

Promote Autophagy

Autophagy is the process by which cells break down and recycle damaged or dysfunctional cellular components. This is an important process for the maintenance of healthy cells and possibly preventing diseases like cancer, Alzheimer’s, and Parkinson’s (13).

Some studies suggest that fasting can stimulate autophagy, leading to enhanced cellular repair processes and improved overall health (9). However, more research is needed to fully understand the role of water fasting in promoting autophagy.

Read more: Green Tea Intermittent Fasting: Benefits and Side Effects

Is Water Fasting Good for Stomach?

There is little scientific evidence to support that water fasting is beneficial for the stomach. In fact, it can lead to some negative side effects such as acid reflux and gastritis, due to the increased production of stomach acid during periods of prolonged fasting (8).

Furthermore, abruptly ending a water fast with a large meal can cause discomfort and even nausea. It’s important to gradually reintroduce food after a fast and listen to your body’s cues to avoid any digestive issues.

Our guide, Water Fasting for a Week ,provides more information on how to safely break a fast and reintroduce food into your diet.

What to Expect During Water Fasting:

If you do decide to embark on a water fast, here are some things you can expect during the process:

See also
Intermittent Fasting For Women Over 50 For Healthy Aging

Hunger and Fatigue

As you are not consuming any calories, it is normal to feel hungry and fatigued during a water fast. This can be especially difficult in the first few days, as your body adjusts to using its energy stores for fuel.

Unpleasant Symptoms

Some people may experience symptoms such as headaches, nausea, and dizziness during a water fast. This is often due to dehydration, withdrawal from caffeine, and hunger. .

Foggy Brain

While some people report enhanced mental clarity during a fast, others may experience the opposite. This is often referred to as “brain fog,” and it’s likely due to the lower energy levels.

water fasting benefits  


Some people may have trouble sleeping during a water fast, due to increased levels of norepinephrine and adrenaline (10). This can lead to restlessness and difficulty falling or staying asleep.


A significant amount of your daily hydration comes from the foods you eat. During a water fast you may find yourself feeling more dehydrated than usual, even if you are drinking enough water. This is because your body is not receiving any hydration from food sources.

Orthostatic Hypotension

Orthostatic hypotension is a sudden drop in blood pressure when you change positions, such as standing up from sitting. Fasting can lead to this condition due to decreased blood volume and lower levels of electrolytes in the body. This may result in dizziness or lightheadedness when standing up (5).

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How Long Is It Safe To Fast on Water?

Short-term water fasting (up to 72 hours) may be safely undertaken by most healthy adults. A medically supervised fast may be advised for those with underlying health conditions.

See also
Fasting Detox: Foods And Drinks To Detoxify Your Body Safely

Periods longer than 72 hours, such as a 30 day water fast, can pose risks and should only be done under close medical supervision. Prolonged fasting can lead to a number of complications:

Nutritional Deficiencies

Without proper nutrition, your body can become deficient in essential vitamins and minerals. This can lead to a weakened immune system, poor wound healing, and other health problems (12).

Electrolyte Imbalance

Electrolytes are minerals that help regulate the balance of fluids in the body and are essential for proper nerve and muscle function. Prolonged fasting can lead to an electrolyte imbalance, which can cause symptoms such as muscle weakness, irregular heartbeat, and fatigue (6). Severe electrolyte imbalances can be life-threatening.

Refeeding Syndrome

Re-feeding syndrome is a potentially life-threatening condition that can occur when someone who has been fasting for an extended period begins to eat again. Rapid re-introduction of food can lead to dangerous shifts in electrolyte levels and other metabolic imbalances (7).


Those who have a history of gallstone formation may be at increased risk of developing gallstones during a prolonged water fast. This is due to decreased bile flow and the release of stored cholesterol from fat cells (3).

Disordered Eating Patterns

Prolonged fasting can lead to or trigger disordered eating patterns and a preoccupation with food. This can result in unhealthy relationships with food and may lead to long-term issues with eating and body image.

Gastrointestinal Issues

Some people may experience digestive discomfort, such as bloating, constipation, or diarrhea during a water fast. This is due to changes in gut bacteria and the lack of fiber and other nutrients typically found in food (8).

Over time, these complications can pose serious health risks and should be taken into consideration before embarking on a prolonged water fast.

See also
7 Zero Calorie Drinks for Intermittent Fasting (And a Few More to Avoid)

Muscle Loss

During a water fast, your body will turn to its stored fat for energy. However, it may also break down muscle tissue for fuel. This can lead to loss of lean muscle mass and a decrease in metabolic rate (2).

Psychological Effects

Fasting can have psychological effects such as irritability, mood swings, and difficulty concentrating. These effects may be exacerbated by prolonged fasting and can impact overall mental well-being (10).

In our 72-hour fast guide, we discuss how to mitigate some of these risks and safely break a fast without causing harm to your body.

Read more: Intermittent Fasting and Running: A Winning Combination or a Terrible Mistake?

What Are Some Signs To Stop Water Fasting?

Stop water fasting immediately if you experience any of the following symptoms:

  • Severe dizziness or lightheadedness
  • Fainting or feeling faint
  • Chest pain or rapid heart rate
  • Weakness and fatigue that does not improve with rest
  • Difficulty standing or walking

If you are experiencing any concerning symptoms, it is important to seek medical attention right away. It may also be beneficial to consult with a healthcare professional before starting a water fast, especially if you have underlying health conditions.

In a previous blog, The 7 Day Water Fast, we discussed the potential benefits and risks of fasting for an extended period.

water fasting benefits  


  • How Much Weight Will I Lose On a 3 Day Water Fast?

You may lose 1-3 pounds per day during a water fast, but the majority of this weight will be from water and stored glycogen (carbohydrates) (14). Keep in mind that lasting weight loss only occurs gradually over time and is best achieved through a healthy, balanced diet and regular exercise.

  • Can You Go 40 Days With Only Water?

While there are anecdotal reports of people completing 40 day water fasts, it is not recommended due to the potential risks and complications that may arise. 40 days is an extremely long period to go without proper nutrition and can lead to serious health issues (2). Always consult with a healthcare professional before attempting any prolonged fasting.

  • Can I Drink Coffee On Water Fast?

It is generally recommended to avoid caffeine during a water fast, as it can increase feelings of anxiety and interfere with sleep. Some experts suggest that a small amount of black coffee may not disrupt the benefits of a water fast, but it is best to err on the side of caution and stick to only consuming water.

  • Can You Build Muscle While Fasting?

No, it is not possible to build muscle while fasting. Fasting puts your body in a state of catabolism (breakdown) rather than anabolism (building (4).You are also not providing any building blocks for new muscle because you are not consuming any protein. If you are looking to gain muscle mass, it is important to consume adequate protein and follow a structured exercise program.

The Bottom Line

While water fasting may claim to have potential health benefits, it is important to consider the risks and complications that may arise. In the short term, you may experience weight loss and a feeling of improved overall well-being. However, prolonged fasting can lead to serious health issues and should only be undertaken under medical supervision. If you are considering trying a water fast, it is important to consult with a healthcare professional first and listen to your body for any warning signs or concerning symptoms.


This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!


  1. β-Hydroxybutyrate (2019,
  2. Efficacy and safety of prolonged water fasting: a narrative review of human trials (2023,
  3. Effects of fasting on the composition of gallbladder bile. (1980,
  4. Fasting: Molecular Mechanisms and Clinical Applications (2014,
  5. Hypotensive effect of fasting: possible involvement of the sympathetic nervous system and endogenous opiates (1982,
  6. Is Water-Only Fasting Safe? (2021,
  7. Refeeding syndrome: what it is, and how to prevent and treat it (2008,
  8. Stomach Acid Interferes When Fasting? Here’s How to Overcome It (2023,
  9. The Beneficial and Adverse Effects of Autophagic Response to Caloric Restriction and Fasting (2023,
  10. The Effect of Fasting on Human Metabolism and Psychological Health (2022,
  11. The Effects of Prolonged Water-Only Fasting and Refeeding on Markers of Cardiometabolic Risk (2022,
  12. The truth about nutrient deficiencies (2022,
  13. Why is autophagy important in human diseases? (2012,
  14. Water fasts can help you lose weight, but you might gain it back quickly (2023,
  15. What’s Water Weight? (n,d,
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