The 10 Day Water Fast: A Complete Guide [How To + What To Expect]

With the pervasiveness of processed foods in the typical Western diet and a general trend of not doing enough physical activity to counteract such a high caloric intake, many of us are often seeking ways to lose weight or “reset” our metabolism.

There are many approaches to dieting and weight loss that may or may not be particularly effective, from the sensible, balanced diet and well-rounded exercise routine to more extreme fad diets and restrictive diets like the Whole30 diet or juice cleanses and detoxes. 

Another increasingly popular approach to weight loss (and other potential health benefits) is water fasting. 

Although short water fasts, like a 24-hour fast, can often be beneficial and not too challenging or extreme to take on, a full 10 day water fast is typically reserved for only special circumstances under guided medical supervision where indicated.

If you are interested in doing a 10 day water fast, keep reading to learn what to expect, the pros and cons of water fasting for 10 days, and tips and potential alternatives that might be safer and more effective.

We will cover: 

  • What Is a 10 Day Water Fast?
  • Potential Benefits of a 10 Day Water Fast
  • Is a 10 Day Water Fast Safe?
  • How to Do a 10 Day Water Fast Weight Loss Diet

Let’s get started!

A clock and a glass of water.

What Is a 10 Day Water Fast?

As the name suggests, water fasting involves abstaining from all caloric food and beverage intake and only consuming water. 

A 10 day water fast extends the duration of this fast for a full 10 days, meaning that nothing but water is consumed for 10 days. 

Although people do 10 day water fasting for different reasons, the primary motivators are usually to aid weight loss, perceived health benefits, or for spiritual or religious reasons.

Water fasting is far from a new practice, as different cultures around the world have practiced versions of fasting in different iterations for hundreds, if not thousands, of years.

With that said, as a mainstream approach to dieting and weight loss, water fasting has become increasingly popular in the past several years, largely in part due to the rise in popularity and success that people have had on intermittent fasting diets.

Water fasting can be seen as an extension of intermittent fasting diets. For example, one type of intermittent fasting diet is the alternate-day eating format in which you alternate between following your normal eating pattern one day and fasting for 24 hours the next.

A person drinking a bottle of water.

Potential Benefits of a 10 Day Water Fast

Studies have shown that extended fasting, such as water fasting for a week or more, can result in positive effects like weight loss, body fat loss, reduced levels of perceived stress, increased ketogenesis, and decreased blood sugar levels. 

Water fasting has also been shown to decrease blood pressure, reduce oxidative stress and inflammation, promote autophagy, and support weight loss.

Some doctors report that water fasting is a good way to “reboot the body.” In some ways, this makes sense, particularly if your usual diet is high in processed foods, sugar, salt, alcohol, and caffeine.

Our brains and taste buds can become accustomed to a certain level of sweetness, saltiness, fattiness, etc. in our foods.

This makes our bodies not only crave more of these foods to produce enough dopamine to set off the “reward centers” in the brain, but also require this same level of flavor intensity to register as something tasty on our palettes.

Pouring a glass of water.

A water fast can essentially reset the “barometer” that our taste buds and brains use to measure the flavor and pleasure derived from foods.

While you might be accustomed to the high sweetness level in fruit juice, soda, sugary cereals, sweets, etc., before water fasting, afterward, something as natural as a carrot might taste intensely sweet.

For this reason, some people do find that water fasting not only results in weight loss during the fast because of the caloric restriction but also helps them adopt and maintain a healthier, more natural diet after the fast is over because cravings for processed foods are reduced.

However, this response can be individualized, and some people find that their urges to binge after fasting are intense, and they struggle with overeating.

Is a 10 Day Water Fast Safe?

Despite some potential benefits of water fasting, there is also evidence to suggest that prolonged fasting may result in adverse health and metabolic changes, and a 10 day water fast is really quite extreme. 

A person drinking a glass of water.

Evidence has demonstrated adverse effects of prolonged fasting, including dehydration, a loss of lean muscle mass, hyperuricemia, hyponatremia, protein sparing, sodium and potassium-sparing, decreased serum calcium and magnesium levels, and acidic urine. 

Moreover, this study only involved fasting for 8 days, so it is even more concerning to consider the potential risks and adverse effects of water fasting for 10 days.

Additionally, extended caloric and nutritional restriction can result in symptoms such as headaches, nausea, vomiting, constipation, the inability to regulate body temperature, muscle loss, lightheadedness, shakiness, poor healing, blurry vision, difficulty sleeping, mood instability, and adverse nutritional deficiencies.

If you have an interest in trying a 10 day water fast for weight loss or health, it is imperative that you work with your healthcare provider and seek medical clearance and guidance before you begin your fast.

Unless you are doing a 10 day water fast for religious or spiritual reasons, there are likely safer and more effective alternatives to weight loss and boosting health.

One of these is moderate time-restricted intermittent fasting diets, such as 18/6 intermittent fasting or a 24-hour or 48-hour water fast.

If you are primarily interested in weight loss, consider working with a registered dietitian and/or certified fitness trainer to create a sustainable, balanced approach to diet and exercise that helps you lose 1-2 pounds per week by creating a modest caloric deficit.

A person drinking a glass of water.

How to Do a 10 Day Water Fast Weight Loss Diet

A 10 day water fast involves drinking only water for 10 days.

Most people ask, “How much water should I drink per day while fasting?“

There isn’t a universal answer to this question, as it depends largely on your body size, as well as the climate in which you live, your sweat rate, and your individual needs.

In general, you should aim to drink a minimum of 1-2 liters of water per day, but more may be necessary, especially if you live in a larger body, sweat a lot, or reside in a hot climate.

It’s important to take in electrolytes as well, especially if you’re drinking more water. 

Without taking in any food during your 10 day water fast, your electrolytes will get very depleted, which, when coupled with water intake, can lead to a potentially fatal condition known as hyponatremia, in which sodium concentration in your body becomes too depleted.

Pouring tea.

It should be noted that some people do permit plain herbal tea during water fasting, but those who follow a strict fasting protocol typically drink only water with added electrolytes and/or supplements such as essential vitamins and minerals.

Black coffee is also technically permitted during an intermittent fasting diet because the caloric content is so small that it is not thought to induce metabolic changes that take you out of the fasting state

One cup (240 ml) of black coffee only contains about 3 calories, along with just trace amounts of protein, fat, and minerals.

Black tea, white tea, green tea, and other caffeinated teas may also be consumed by some fasters, although water fasting protocols usually recommend eliminating all sources of caffeine during the fasting protocol.

As much as the focus on water fasting is on not eating during the fast, it should also be what to eat after the 10 day water fast is over.

Refeeding syndrome, a dangerous condition caused by rapid changes in electrolytes and fluid balance after prolonged fasting, can occur if you eat too much too soon after fasting for so long.

A nutritionist working with a patient.

To prevent refeeding syndrome after a 10 day water fast, you need to gradually ease back into eating and choose foods to break your fast that are lower in carbohydrates and gentle on the stomach, such as bone broth, steamed vegetables, fermented foods, and soups.

Make sure you get individualized guidance from your healthcare team about what you should eat to break your fast.

Water fasting can potentially be a route to achieve numerous physical and mental health benefits and support significant weight loss. 

However, water fasting for 10 days is an extreme scenario that should only be conducted under the supervision of a trained healthcare professional.

Consider other alternatives to dieting and health that might better suit your needs while sidestepping some of the risks of a 10 day water fast, such as intermittent fasting. For a guide to intermittent fasting schedules, click here.

Intermittent fasting written on a notebook.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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