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The Science Behind Water Fasting: Understanding its Effects

- Written By

Sana Farhan, MS Healthcare

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This article is based on scientific evidence, written by experts and fact checked by experts. Our team of experts strive to be objective, unbiased, honest and to present both sides of the argument. This article contains scientific references. Read more about our process.

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Water Fasting for Weight Loss: Does It Work?

In water fasting, which has become more famous recently, you don’t eat for a particular time; you consume water. Individuals have been fasting for hundreds of years for various causes, including religious or spiritual practices and possible health advantages.

How your body works changes a lot when you only drink water. As a result, the body enters a condition of ketosis when it burns stored fat for energy. This method promotes enhanced cognitive focus, cell regeneration, and weight loss, among other advantages.

But if you try water fasting, go cautiously because it might be risky and unfit for everyone. In this article, we’ll explore water fasting, addressing its advantages and disadvantages, helpful application advice, and potential refeeding syndrome symptoms. So, read on to learn everything you need to know if you’re interested in water fasting and want to try it.

How to do water fasting?

Here are some suggestions to follow if you decide to go forward with a water fast:

1) Preparation

 Progressively reduce your calorie consumption for a day or two before beginning a water fast. Consume light, readily absorbed meals to minimize pain as you enter the fast.

2) Choose a time frame.

Choose the length of your water fast. While experienced more quickly could go for several days or even longer, beginners frequently start with shorter fasts, such as 24 to 72 hours. Only use extreme caution and seek medical guidance before attempting long fasts.

3) Relaxation

 During the fast, engage in low-intensity activities because your energy levels may be lower than usual. Get lots of rest, and steer clear of excessive exertion.

4) Observe your body

 Keep a watchful eye on your feelings when you’re fasting. Consider breaking the fast and getting medical help if you develop significant pain, lightheartedness, or other unsettling symptoms.

5) Breaking the fast

 Stay away from eating regular meals when the fasting time is complete. Start with modest servings of meals that are simple to digest, including fruits, vegetables, or soups. Reintroduce solid foods gradually over a few days.

6) Potential hazards

 A water fast can result in electrolyte imbalances and vitamin shortages, both harmful to your health. It is advised to avoid moisture fasting entirely if you have any health issues, are pregnant, are nursing, or are underweight.

7) Monitoring

Keep a tight eye on your health the whole fast. Stop the fast and get medical help if you experience any adverse effects or feel sick.

What are the advantages of water fasting?

Here are some other advantages of water-only fasting:

 1) Weight reduction

 Water-only fasting, particularly during prolonged fasts, can cause substantial weight reduction. When you don’t eat, your body uses its fat reserves as energy, which makes you lose weight. It’s important to remember that weight loss during fasting is frequently sporadic and is easily reversible once regular eating resumes.

Related Article: Top 10 High Thermic Effect Foods To Include In Your Weight Loss Diet

2) Autophagy

Fasting may cause the human body to activate a process known as autophagy. A cell’s ability to break down and recycle defective or malfunctioning parts is known as autophagy. This procedure encourages cellular well-being and rejuvenation by removing outdated and potentially toxic substances.

3) Enhancing Insulin Sensitivity

According to certain studies, water fasting may enhance insulin sensitivity.

4) Mental Clarity and attention 

Some people claim that fasting on water improves their ability to think clearly and pay attention. This is believed to result from the body switching from using glucose as its primary energy source to using ketones, which are created from fat breakdown.

5) Eating habits

Water fasting might help you reset your eating habits if you have any unhealthful ones. It offers a chance to rethink and develop more nutritious eating habits and enables people to move away from excess eating or choosing unhealthy eating decisions.

6) Digestive Rest

Fasting gives the digestive system time to recover from breaking down food, which is suitable for people with digestive problems. It might give the gut a time to recover and lessen signs like bloating or discomfort.

7) Decreased Inflammation

According to some research, water fasting could alleviate the body’s natural signs of inflammation. Numerous medical illnesses, such as autoimmune disorders and heart conditions, are associated with persistent inflammation.

8) Potential Effects on Longevity

. Some investigators hypothesize that fasting’s induction of cellular repair and stress tolerance may benefit lifespan, though further research is needed to confirm this.

What are the drawbacks of Water fasting?

Water fasting has a lot of possible benefits and drawbacks. Before starting or even considering a water fast, you must be aware of these concerns. The following are some of the primary dangers connected with water:

1) Dehydration

When on a water fast, dehydration is a highly probable issue since you only consume water and do not consume anything else from meals. Dehydration can cause a mouthfeel that is dry, weariness, and dizziness. Dehydration poses a particular risk to people with specific medical conditions.

2) Electrolyte imbalance

Essential electrolytes, including sodium, potassium, and magnesium, may experience a shift in their equilibrium due to water-only fasting. These electrolytes are necessary to maintain normal neuronal and muscle activity. Extreme imbalances may manifest as lethal conditions such as racing hearts, contractions of the muscles, or cardiac arrhythmias.

3) Nutritional deficits

Nutritional deficits, such as a lack of minerals and vitamins, may result from protracted water fasting. Insufficient vitamins can affect the body’s immune system, bone health, and general well-being.

4) Diminished energy

Long-term water fasting can cause severely diminished energy, which makes it challenging to finish everyday tasks. This may prove harmful if you have responsibilities requiring mental and physical focus.

5) Orthostatic Hypotension

 During water fasting, blood pressure can decrease, rendering it difficult for one to get up from a seated or laying posture without becoming lightheaded or faint.

6) Muscle loss

The loss of muscles occurs because the human body destroys muscle tissue seeking energy, much like starving on water. This might be difficult for people who want to keep or gain muscle.

7) Gallstones

If an individual loses a substantial amount of pounds quickly during fasting, especially if they possess a history of gallbladder problems, they may be more susceptible to developing gallstones.

8) Weaken immune system

Long-term fasting could compromise the immune system, leaving the human body more vulnerable to diseases and infections.

9) Eating disorders

Eating disorders like orthorexia or binge eating can be made worse by or helped by liquid fasting.

10) Effect on mental well-being

Water Fasting can harm your mental health, mainly if you practice it frequently. These consequences can include mood changes, increased tension, worry, etc.

Refeeding Syndrome

 After an extended fast, there is a chance to experience refeeding syndrome, which is risky since it occurs when the body suddenly increases its metabolic rate in response to the food that has been reintroduced.

Signs of Refeeding Syndrome

Refeeding may cause your face, legs, or other body parts to swell if you retain fluid.

  • Cardiac Arrest

The cardiovascular system may be impacted by refeeding syndrome, which may lead to palpitations, irregular heartbeats, and, in severe cases, cardiac arrest.

  • Chest Pain

Refeeding syndrome patients may develop chest pain or breathing problems.

Related Article: A Surprising Discussion: Can Constipation Cause Chest Pain?
  • Neurological illnesses 

Neurological illnesses such as confusion, agitation, epileptic fits, and other neurological symptoms can be brought on by electrolyte changes affecting brain function.

  • Digestive issues

Refeeding may cause digestive issues such as gas, diarrhea, vomiting, and nausea.

  • Muscle Soreness & weakness

 Low-calorie intake and electrolyte imbalances can lead to severe muscle soreness and weakness.

  • Oedema:

When the body retains fluid, it can cause swelling, notably in the hands, feet, and ankles.

  • Hyperglycemia

The refeeding syndrome may result in hyperglycemia (high blood sugar) or hypoglycemia (low blood sugar).

  •  Lethargy & exhaustion

People with the refeeding syndrome may feel quite worn out.


Yes, there are other ways to improve health and lose weight, like eating a balanced diet, working out frequently, and getting advice from certified dietitians or other medical professionals.

Breaking the fast and getting medical help immediately is crucial if you experience significant discomfort, lightheadedness, weakness, or other unsettling symptoms while on a water fast.


Water fasting is a severe type of fasting that entails giving up all meals and drinking just water for a set amount of time. It carries a lot of hazards, even if it might have advantages like weight loss, better insulin sensitivity, and autophagy.

Extended water fasting can result in dehydration, electrolyte imbalances, vitamin shortages, weariness, and other health problems. As a result, before beginning water fast, it’s essential to exercise caution and obtain advice from qualified medical personnel or licensed nutritionists.

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Trend Of Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy

All you need to know about Water Fasting
Researches. Benefits, and How to

Five-day water-only fasting decreased metabolic-syndrome risk factors
Increased anti-aging biomarkers without toxicity in a clinical trial of normal-weight individuals



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