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Home arrow Nutrition arrow Intermittent Fasting arrow Water Fasting: What Is It, and How Does It Work?

Water Fasting: What Is It, and How Does It Work?

Written by Edibel Quintero, RD
Fact checked by Rosmy Barrios, MD
Last update: October 17, 2023
8 min read 1473 Views 0 Comments
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Losing weight can be challenging, especially if you have stubborn fat. Water fasting is one of those methods that can speed up results, but is this healthy? How does it support weight loss? We detail everything to do with water fasting and how it works.

water fasting

Consuming enough water is always important for a healthy diet.

You need to stay hydrated when losing weight and keeping the fat off. Intermittent fasting is a dietary method that encourages more water intake. This fluid aims to keep you full during non-eating periods, which is great for reducing hunger spikes throughout the day. 

Water fasting is a common option for people to only drink water during the fasting periods. You can avoid food for 24 hours and onwards, but is this healthy for you? It’s perfectly normal to think about the risks of fasting and whether it’s right for your fitness goals.

In this article, you’ll learn more about water fasting and how it works.

What Is Water Fasting?

Water fasting is a type of fast that requires you to only drink water for 24–72 hours. You should not exceed this time period since it may cause future health problems. 

Most people desire weight loss plans that encourage fast but safe results. Intermittent fasting is a popular option that restricts your eating pattern. The 12-hour fast is a common method among beginners, but water fasting is a challenge even for advanced fasters.

On some intermittent fasting methods, you can drink unsweetened tea, coffee, or even bone broth. However, this is not suitable for water fasting. Pure water is the one thing you can consume during fasting windows. Any other products containing calories may disrupt your fasting progress. 

How Long Can You Water Fast?

The water fast should only last between 1–3 days. Never fast for more than 3 days, as this may trigger starvation mode – a dangerous muscle-burning state. 

Everyone has different weight loss goals that may affect intermittent fasting. If you want to lose 20 pounds, you might choose to water fast for 3 days. Other people may only try this fasting method as a mental challenge to see if their body feels better after drinking just water. 

You can repeat this water fast once a month or every other week. Don’t starve your body of vitamins and minerals, as this can damage your kidney function. Eating windows should contain foods that are high in nutrients and help protect the digestive system. 

How Much Weight Can You Lose Fasting?

You can lose up to 2 pounds a week when trying fasting methods. This figure depends on your body weight, fasting type, calorie consumption, and physical activity. 

During any intermittent fasting plan, you should aim to lose 1–2 pounds a week. This is a healthy amount to lose when restricting calories. It’s better not to exhaust yourself if you’re exercising regularly too. Weight loss takes plenty of time and dedication, so never rush it. 

A water fast can help you see noticeable changes in a few weeks. Since you’re limiting calories in 1–3 days, your metabolism removes body fat. Just remember that this is a short-term fasting method that shouldn’t be repeated in the same week of finishing it. 

How Do You Water Fast?

You need to choose a day to start water fasting. Many people cut out food and drinks on a Monday morning and then finish the fast on Wednesday. However, you should prepare to do this fast, as it can be challenging to not eat for over 24 hours.

Preparation is the first step, as it can help you feel ready not to eat. Consider eating full meals the night before to fuel your body with energy. These meals should be healthy and packed with nutrition. To lose weight, you need to monitor your calorie intake throughout the week.

Now it’s time to start the water fast for your desired duration. If you’re new to fasting, try drinking water for just 24 hours. This will help your body adjust to the new lifestyle change. More advanced fasters can complete the water fast in 72 hours to see more physical results.

Once those hours are up, you need to break the fast safely. Eat a small meal that is easily digestible. You don’t want stodgy foods that could trigger constipation. Fish, smoothies, soups, fresh fruit, and organic vegetables are great products to have. 

After completing any type of fast, start eating smaller meals and slowly return to your regular diet. It might be tempting to eat loads of food, but you don’t want to harm your digestive system.

Benefits of Water Fasting

There are plenty of health benefits that derive from water fasting and limiting food intake. People might try this method to prevent medical conditions or strengthen their overall body.

Here are four health benefits of water fasting: 

#1 Autophagy

Water fasting can trigger autophagy – a regeneration process that encourages your body to eliminate potentially dangerous cells. This transformation can keep existing cells healthy and maintain neurons in the brain and cardiomyocytes for the heart muscles.

#2 May help improve insulin sensitivity

Any type of fasting can reduce insulin resistance and prevent your blood sugar levels from getting too high. This is due to the lack of carbs and sugar being fed to the body. If you go above the healthy blood sugar range, you might be at risk of diabetes. 

Constantly eating means your insulin levels will continue to rise and fall throughout the day. Water fasting can stabilize glucose storage and give your pancreas a rest. Decreasing insulin sensitivity also slims down your waist, as the glucose is being burned and not stored away.

#3 May lower the risk of some chronic diseases

Water fasting can lower high blood pressure in those who have abnormal cholesterol levels. 

This can reduce health risks like heart disease, cardiomyopathy, heart failure, strokes, and cardiovascular disease – all of which damage your heart permanently. 

You can choose to drink water during alternate-day fasting. Drinking enough fluids encourages the heart to pump blood through the body more effectively. Hydration is important for preventing strain on the heart muscle and other risk factors associated with water depletion. 

#4 Weight loss 

Many people choose water fasting to lose weight and regulate their fluid and electrolyte levels. If these levels aren’t balanced, your body can’t sustain good weight loss. A lack of strong electrolytes will also lead to health conditions like coma, seizures, and cardiac arrest.

You need water to increase muscle mass after burning fat on several parts of your body. This can help you feel stronger after fasting for extended periods. Water boosts your metabolism, suppresses your appetite, and strengthens your performance during workouts.

You can use a fasting app to follow fasting programs that have the most health benefits. It will test your willpower limits and encourage you to reduce food intake safely.

Side Effects of Water Fasting

Any type of dietary plan can have side effects that trigger certain health complications, like high systolic blood pressure, eating disorders, low blood sugar levels, and chronic diseases. 

It’s important to mention that you should seek medical supervision if you’ve never tried water fasting when losing weight.

Let’s take a look at 3 potential side effects of water fasting: 

#1 May cause dehydration

Even though you might be drinking water, you can still get dehydration by not consuming enough during the day. 

The human body gets about 20% of water from food, so cutting out food completely for 24–72 hours can deprive your body of healthy fluids.

To check that you’re not dehydrated, examine the color of your urine to make sure it’s not a dark yellow. A musty color means you’re not consuming enough water to fuel your organs. A dry mouth, headaches, tiredness, and severe thirst are further signs of dehydration. 

#2 Can worsen medical conditions

Water fasting can trigger blood pressure changes, especially if you’re already taking medication to maintain blood pressure levels in your body. You should speak to a medical professional before trying this intermittent fasting method, as you don’t want to damage your overall health. 

If you suffer from gout, water fasting might not be the right type of fast. Trying this lifestyle change could increase uric acid production and lead to gout attacks. Consider looking at other fasting options or weight loss methods that don’t pose many health risks.

Those prone to eating disorders are also recommended not to try water fasting. Cutting out food completely can encourage bulimia in younger adults. You should seek medical supervision from someone who is aware of your eating disorder and can help you through fasting.

#3 Nutritional deficiencies

Since you’re cutting out food for 1 to 3 days, you’re not fueling your body with the right nutrition.

Water fasting once or twice a month is safe, but exceeding this amount can lead to nutritional deficiencies. This is due to your body not getting enough vitamins, minerals, and protein. 

How to Safely Fast

You need to follow safe methods when trying water fasting. This prevents your body from becoming weak. Consider talking to your doctor about water fasting and how you can maintain a strong immune system when losing weight.

Preparation is also key before starting any fast. You can try other beginner fasting methods, like the 16:8 eating pattern that requires you to eat in an 8-hour window. 

The lemon detox cleanse is another method that involves mixing lemon juice, maple syrup, cayenne pepper, and water to remove toxins from your body. This is a good liquid-based diet to try for 24 hours before moving on to water fasting.

Remember that you shouldn’t break the fast with junk food. This will only increase your chances of gaining weight. Stick to soft foods like soup, smoothies, dried fruits, bone broth, and eggs when breaking a fast. You can eat normal meals again once you’ve eaten easily digestible foods for 24 hours.

The main thing is to stop fasting if you don’t feel well. Constant headaches, vomiting, constipation, and dizziness are signs you should return to a normal diet

Weight loss shouldn’t damage your health, so drink plenty of water and don’t go without food for over 3 days. 

A Word From Our Nutritionist

Water fasting is great for people who want to lose weight.

Cutting out food for 1–3 days might seem intimidating, but it can help cleanse your body of stubborn fat. Drinking only water during medically supervised intervals may encourage smooth weight loss over a few weeks. However, there are bound to be health risks with a water fast.

Those who have high blood pressure should seek professional medical advice before trying this fasting method. You need to understand the health concerns associated with blood pressure changes and how your body might react to isolated water consumption.

Pregnant women, people with type 1 and 2 diabetes, and older adults suffering from heart disease should not try this diet without consulting a doctor first. It’s essential to learn your nutritional needs, especially if water fasting deprives you of compulsory foods.

Even though there might be risks, a water fast is believed to provide many health benefits. It can help you lose weight, prevent blood sugar levels from rising, improve insulin resistance, and remove dangerous cells – all of which strengthen your overall body.


You can try water fasting to lose weight, but always check with your doctor that it’s suitable for your fitness journey.

This non-eating period can produce health benefits like lower blood pressure, reduced risk of heart disease, stronger muscles, and improved joints.

Written by Edibel Quintero, RD
Edibel Quintero is a medical doctor who graduated in 2013 from the University of Zulia and has been working in her profession since then. She specializes in obesity and nutrition, physical rehabilitation, sports massage and post-operative rehabilitation. Edibel’s goal is to help people live healthier lives by educating them about food, exercise, mental wellness and other lifestyle choices that can improve their quality of life.
The article was fact checked by Rosmy Barrios, MD
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Written by Edibel Quintero, RD
Fact checked by Rosmy Barrios, MD
Last update: October 17, 2023
8 min read 1473 Views 0 Comments

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