How Much Weight Will You Lose on a 28 Day Water Fast? (Is It Safe?)


If you’re considering a 28 day water fast, you may be wondering how much weight you can expect to lose.

While results will vary depending on a number of factors, it is possible to lose a significant amount of weight in 28 days, but is it safe?

A 28 day water fast is not recommended for safe weight loss.

Let’s take a look at what you can expect and why you should avoid this length of time fasting.

What is Water Fasting?

Water fasting is a type of fasting in which you consume only water for a period of time.

Water fasting is usually done for religious or spiritual purposes, but it can also be done for health reasons.

Some people believe that water fasting helps to cleanse the body and mind, and can even lead to spiritual enlightenment.

One example of this is Jainism. Fasting is widely popular among Jains and as a part of festivals that they take part in.

Jains will fast at special times such as birthdays, special anniversaries, during their festivals, and on holy days.

Jains maintain a strict water based fast for 8 to 10 days. This is done during the days of Paryushan.

Water fasting is not for everyone, and it is important to speak with a doctor before beginning a fast.

Water fasting can actually be deadly, especially with individuals with congestive heart failure and valvular problems within the heart, diabetes, and other health conditions.

However, if done correctly for the correct amount of time, water fasting can be a safe and effective way to improve your health.

Again, I will stress, always speak with your doctor before starting any type of water fast.

Benefits of Water Fasting

People with risk factors for certain diseases could benefit from short-term fasting. These benefits can include:

  • Preventing heart disease
  • Preventing or decreasing high blood pressure (Hypertension)
  • Lowering cholesterol levels
  • Preventing or helping to control diabetes
  • Weight loss (if done correctly)

Risks of Water Fasting

One of the most serious risks is imbalance of electrolytes.

Because water fasting involves drinking only water, it can cause the body to lose electrolytes, which can lead to dizziness, weakness, and even seizures.

When we are consuming copious amounts of water, we dilute many electrolytes which can lead to things such as hyponatremia.

Hyponatremia can be very dangerous! It can even lead to brain swelling and death in extreme cases.

Another potential danger of water fasting is that it can put stress on the kidneys and other organs. This can cause acute kidney injury (kidney failure).

Without solid food to digest, the organs must work harder to filter out toxins and waste products. This can lead to fatigue, headaches, and other symptoms.

Finally, water fasting can also lead to an imbalance of gut bacteria, which can suppress the immune system and make a person more susceptible to infection.

Have you ever heard of the woman who died by drinking extreme amounts of water?

This woman died of water intoxication by taking part in the “Hold Your Wee for a Wii” contest.

She tried to drink as much water as she could in a short amount of time to win this Wii gaming system.

While this is a very extreme case, it does show you the effects that drinking insane amounts of water can have on our bodies.

risks of water fasting- hospitalized person

For the above reasons and risks of excessive fluid intake, it is important to consult with a doctor before embarking on a water fast.

Why Would Someone want to Water Fast to Lose Weight?

People often do water fasting to lose weight quickly, as it is a definite way to reduce calorie intake.

Water fasting also can cause you lose weight by making you feel fuller and reducing your appetite as well.

When we fill our stomach with volume, it sends a signal to our brain which tells us we are full.

Water also has the ability to reduce our hunger hormone, ghrelin.

Ghrelin signals to our brain that we are hungry and need to eat. So, by reducing the levels of ghrelin in our body, we can effectively decrease our appetite.

It is important to remember however, that trying to lose weight very quickly is not going to work long term.

You need to learn how to lose weight in a calorie deficit in a healthy way by building a healthy relationship with food. This way you will have long term success that could last for the rest of your life.

How Much Weight Can you Lose on a 28 Day Water Fast?

You might be surprised when water fasting that your weight may actually increase.

This is because you are gaining weight from fluid.

Of course, over time, you will be in a caloric deficit and you will start to burn fat, which will cause you to lose weight.

You can expect to lose a significant amount of weight on a 28 day water fast. You can expect to lose anywhere between 10-20 pounds depending on your physical activity.

However is this safe?

Water Fasting for 28 Days is Unsafe for Losing Weight

28 days is a long time to go without food, and there are potential risks associated with water fasting for this amount of time.

Going without food for this extreme of a length of time can actually cause nutritional and dietary imbalances.

Fasting for 28 days actually has the ability to cause malnutrition.

Water fasting for 28 days can cause malnutrition because the body is deprived of essential nutrients.

Without a regular intake of calories and nutrients, the body will start to break down its own muscle tissue for energy. You do not want this.

This can lead to weakness, fatigue, and a decrease in immune function.

In addition, water fasting can cause dehydration, which can further contribute to malnutrition.

When the body is deprived of water, it begins to recycles its own fluids, leading to a build-up of toxins in the blood.

This can cause serious health problems, including organ damage. For these reasons, it is important to consult a doctor before undertaking any type of fasting regimen.

Fasting may be harmful to your health if not done correctly.

The additional risks can include electrolyte imbalance, kidney damage, and an suppressed immune system as we discussed. You do not want to subject yourself to any of these risks.

For these reasons, it is not recommended to water fast for 28 days to lose weight. If you are looking to lose weight, there are other, safer methods that you can try.

You can read this helpful article below about losing weight with a healthy calorie deficit. This way you can lose weight more effectively over a longer period of time, which will give you results that last.

You can also eat foods you love!

Related post: Eat Whatever You Want in a Calorie Deficit

If you do have your mind made up and have chosen you would like to water fast to lose weight, consider a 72 hour water fast.

Alternative: 72 Hour Fast for Weight Loss Results

A 72 hour fast is a safer alternative to water fasting for 28 days to lose weight.

Fasting for 72 hours may help you to lose weight by “resetting” your metabolism.

This is particularly helpful if you are in a weight loss plateau and you need a slight boost.

When you fast, your body is forced to break down stored glycogen for energy, which can lead to weight loss.

In addition, fasting can help to increase levels of human growth hormone, which can help to promote muscle growth.

Fasting for 72 hours can also help to reduce inflammation, which can lead to weight loss by reducing water retention.

Finally, fasting for 72 hours can help to increase levels of norepinephrine, a hormone that helps to burn fat.

As a result, fasting for 72 hours may be an effective way to lose weight and improve your overall health.

If you are keen on water fasting, you can opt for the 72 hour method, rather then the dangerous 28 day water fast.

I am going to add in my own 2 cents here. I personally do not feel this method is going to help you in a significant enough way to give you the results you are after.

The only way to get long term results is by utilizing a calorie deficit.

I have said it before and I will say it again, a calorie deficit is the only way to lose weight. It works every single time.

Creating a healthy calorie deficit is going to give you the results you are after, and you are going to learn how to lose weight and not build unsafe relationships with eating.

Losing weight does not have to be hard. It is all based on our mindset.

Intermittent Fasting for Weight Loss

Intermittent fasting is also a helpful way of losing weight.

This is not a specific type of “diet” but is rather a pattern of eating.

The most common example of intermittent fasting is one that I have experience utilizing. I do feel comfortable recommending this method, because in addition to helping you better utilize calories, it also has other benefits.

Simply put, you will stop eating around 8 or 9PM, and start eating again 16 hours later.

This would mean you would have your first meal or snack around 12-1PM the following day.

For most people, this is doable. You may even be surprised to know you already do a form of this already in your schedule, you just may need to extend the timeframe of the fasting period.

This type of intermittent fasting can help you to lose weight by decreasing your calorie intake for the day in an easier way.

You will be able to eat more foods later in the day too which can help you to feel less deprived.

Intermittent fasting has other great benefits such as improving insulin sensitivity, lower cholesterol levels, and reducing inflammation.

It has also been shown to boost brain health by increasing levels of BDNF, a protein that promotes the growth of new nerve cells.

Intermittent fasting is also thought to increase lifespan by protecting cells from damage and reducing the risk of age-related diseases.


While more research is needed in this area, the potential benefits of intermittent fasting are significant.

Also, by cycling on and off of intermittent fasting, you are going to keep your body and metabolism guessing. Your body will not become stagnant and accustomed to the same old routine day in and day out.

As a result, it is likely to become an increasingly popular weight loss strategy in the years ahead.

Related post: Does it Matter When You Eat on a Calorie Deficit?


Here is a list of common questions related to water fasting and weight loss.

1. Will I lose weight on a 28 day water fast?

Yes, but it is not recommended to water fast for 28 days to lose weight. This can be dangerous and lead to health complications. There are other, safer methods of losing weight that you can try instead.

2. What are the risks of a 28 day water fast?

The risks of a 28 day water fast include electrolyte imbalance, kidney damage, and an suppressed immune system amongst other dangers. This can lead to health complications.

3. What are the benefits of fasting for 72 hours?

Some potential benefits of fasting for 72 hours include resetting your metabolism, and increasing levels of human growth hormone

4. How much weight can I lose on a 72 hour or 3 day water fast?

You can expect to lose up to 2 pounds each day of a 72-hour water fast. Although, you must keep in mind that the majority of the weight you lose during the 72 hours will likely not be pure fat loss.

You will still reap the benefits as it relates to your metabolism.

In Summary

While 28 day water fast may help you to lose weight in the short term, they are not safe and can lead to many health problems. I do not recommend this method.

If you are looking to lose weight, there are other, safer methods that you can try, such as a trusted staple, a healthy calorie deficit for long term success.

Intermittent fasting is another helpful way of losing weight that has many other great benefits such as improving insulin sensitivity, lowering cholesterol levels, and reducing inflammation.

Intermittent fasting can also help you to maintain your goals while in a healthy calorie deficit.

Remember, you want to lose weight in a way that is healthy, sustainable, and enjoyable.