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Dry Fasting: The Latest Trend in Fasting Is Taking the Health World by Storm—But Is It Safe?

By Fitoru | 26 November 2019
wooden bowl of mixed dried fruits

The practice of abstaining from food or drink for religious or health purposes has featured prominently in various cultures for thousands of years. Even the legendary Greek physician Hippocrates recommended fasting to patients with certain medical conditions. However, while there’s indeed evidence to suggest that some forms of fasting can be healthy, when taken to extremes, the potential health benefits are lost and serious side effects can result. In this article, we’re going to dig into the ins and outs of dry fasting and find out everything you need to know about the potential benefits and risks of this hottest new trend in fasting.

What Is Dry Fasting?

Unlike juice or water fasting, which involves subsisting on liquids for a set period of time, dry fasting, as the name suggests, requires the elimination of both food and liquids. Restricting the diet to, well, nothing makes dry fasting the most restrictive form of fasting there is.

Like regular fasting, dry fasting has been a part of religious observances for centuries. For example, Muslims are required to abstain from all food and drink between sunrise and sunset for the entire month of Ramadan.

The practice of Ramadan originated in countries where the hours of daylight average around 12 hours (granted, Muslims in far northern countries have a much harder time of it, with days averaging 20 hours or more), making this type of intermittent fasting relatively safe for the average person.

However, some advocates of dry fasting for health take its use to extremes and may fast for two or more days at a time.

That said, there are several much safer forms dry fasting may take.

Types of Dry Fasting

When it comes to dry fasting, there are several fasting methods to choose from, but the most common are:

  • 16/8 dry fast: With this type of intermittent fasting, you follow a regular diet for 8 hours and abstain from food and water for the other 16.
  • 20/4 dry fast: With the 20/4 fasting method, eating food and drinking water is allowed for 4 hours, followed by dry fasting the other 20.

The 16/8 and 20/4 dry fasts can also be either soft or hard.

  • Soft dry fast: During this type of dry fast, even though you’re not allowed to drink water, you can still come into physical contact with it, which means brushing your teeth, swimming, and taking a shower are all on the menu.
  • Hard dry fast: With this type of fast, which is also called an absolute fast, all forms of contact with water are off limits—so that means no showers and no dental hygiene.

Potential Health Benefits of Dry Fasting

As mentioned, intermittent fasting is associated with a number of health benefits, from lower blood pressure, cholesterol, and blood sugar levels to weight loss, decreased levels of inflammatory markers, and improved heart and brain health.

So why do dry fasting? 

When you talk to proponents of dry fasting, they’ll tell you that as powerful as regular fasting is, dry fasting is even more powerful. 

But what does the science have to say?

Unfortunately, when it comes to dry fasting, very little, as its widespread use is a relatively new phenomenon.

However, some studies have been performed—mostly on groups who engage in dry fasting for religious reasons—so let’s take a look at those now.

Potential Health Benefits of Dry Fasting

Weight Loss

While it would seem to make sense that engaging in the type of calorie restriction that goes along with dry fasting (or any type of fasting, for that matter) would lead to at least some weight loss, decreased calories aren’t the only weight-loss factor of a dry fasting diet.

There’s also water weight. In fact, approximately 60% of the human body is made up of water, so much of the weight loss seen during a dry fast is due to water loss.

What’s more, every time you take in calories, insulin is released. The purpose of insulin is to help the sugar (glucose) from the calories you ingest get into the body’s cells, where it can be used for energy. However, once the body’s immediate energy needs are met, any remaining glucose is converted into fatty acids, which are then stored for later use as fat.

Anyone who’s ever tried losing weight knows how hard it can be. And one of the reasons for this is that even normal levels of insulin can make it difficult for fat cells to release their lipids so they can be burned for energy.

This is why intermittent fasting can be so helpful for weight loss. By restricting calories, insulin levels are reduced, which increases the amount of fat released for energy.

Although the benefits of calorie restriction have been documented in numerous animal studies, proponents assert that dry fasting is even more powerful than regular fasting.


Because putting the body in a state of near dehydration causes it to search for water in other places. And one of these places is fat. 

To back up this claim, dry fasting advocates point to the fact that every 100 grams of fat can produce approximately 110 grams of what’s known as metabolic water. Though this assertion is true, it also tends to ignore the fact that metabolic water can be produced using both carbohydrates and protein—the building blocks of muscle tissue.

Does this mean that dry fasting destroys muscle tissue?

According to a study published in the International Journal of Endocrinology and Metabolism, no. 

In this study, researchers looked at 43 Ramadan participants to compare caloric intake, body mass index, weight, body composition—including protein, minerals, water, and body fat—and waist-to-hip ratio. All measurements were taken on the 1st and 28th days of Ramadan as well as 4 to 5 weeks after the fasting period was over.

At the end of Ramadan, researchers found that even though total caloric intake remained unchanged, participants still experienced significant decreases in body fat, body weight, body mass index, and mineral and water content. However, there was no associated loss of muscle mass.

Granted, this is only one study, and it involved Indonesian participants, who experience about 12 hours of daylight during Ramadan and so would be dry fasting for half a day every single day of their holy month.

You can also compare these findings with studies that have suggested that the greatest drop in insulin—and therefore greatest increase in ketosis, or fat burning—occurs 18 to 24 hours after the start of a fast.

Brain Health

Numerous studies have found a link between intermittent fasting, calorie restriction, and improvements in brain health.

For example, a study published in the journal Brain Research Reviews found that ketone bodies—compounds released during fat metabolism—formed during periods of calorie restriction have a neuroprotective effect.

The calorie restriction that occurs with fasting also results in a beneficial byproduct called autophagy. During this process, the body responds to stress or what it perceives as starvation by eating itself.

We know that sounds absolutely awful, but in the case of autophagy, it’s actually a good thing. And that’s because, during autophagy, the body begins to digest and recycle all the things it doesn’t need, like damaged cells, pathogens, and deformed proteins, and turn them into newer, healthier cells.

As you can imagine, autophagy has benefits for the entire body, including the brain. In fact, it’s been found to help stave off neurodegenerative diseases like Parkinson’s and Alzheimer’s disease.

In addition, a study published in the journal Neurology International involving Ramadan participants found that dry fasting leads to significant increases in levels of brain-derived neurotrophic factor (BDNF), serotonin, and nerve growth factor (NGF).

This is an especially important finding, as all three of these compounds play an important role in brain health.

BDNF not only helps modulate neurotransmitters and maintain the health and growth of neurons, but it also plays a role in learning and memory. Likewise, NGF helps prevent neurodegeneration. And the neurotransmitter serotonin helps maintain normal mood, appetite, digestion, sleep, and memory as well as sexual function and desire.

Diabetes and Heart Health

One of the most important predictors of chronic disease is inflammation. Although acute inflammation is an important part of a healthy immune system response, studies have found that inflammation that persists past the acute phase is associated with the development of a number of diseases common in the West, including heart disease.

However, the intermittent dry fasting practiced as part of Ramadan has been found to reduce levels of inflammation. In fact, a study published in the journal Nutrition Research found that dry fasting during Ramadan leads to significant decreases in both inflammatory markers and blood pressure, body weight, and body fat percentage, elevated levels of which are associated with a higher risk of heart disease.

Similarly, a study in the journal PLoS One demonstrated that dry fasting during Ramadan leads to significant reductions in blood pressure, body weight, waist circumference, triglycerides, and LDL, the so-called bad cholesterol. What’s more, the cholesterol benefits were found to continue for up to 4 weeks after the end of Ramadan.

The effects of dry fasting during Ramadan have also been investigated for their potential benefits for diabetes. 

For example, a study published in the Journal of the Egyptian Public Health Association found significant decreases in a number of parameters associated with both diabetes and heart disease, including blood glucose, glycosylated hemoglobin (a measure of blood sugar averaged over 2 to 3 months), cholesterol, triglycerides, bilirubin (high levels of which are associated with liver disease), uric acid (high levels of which are associated with both gout and kidney stones), and blood pressure.

Bone Health

Interestingly, it seems that dry fasting may also have benefits for your bones. In fact, a study published in the journal Therapeutic Advances in Endocrinology and Metabolism found that intermittent dry fasting during Ramadan modulates the release of parathyroid hormone (PTH). 

This finding has potential implications for the prevention and treatment of osteoporosis, as PTH not only promotes the absorption of calcium but also stimulates bone formation and resorption.

Performing a Dry Fast

Dry fasting is the most extreme form of fasting there is, and it can be dangerous if it’s not done properly. So anyone interested in dry fasting should first acquaint themselves with less strenuous types of fasts.

If you’ve never done any kind of fast before, a good way of working up to a dry fast is to start with a 1-day juice fast. If you can get through 1 day of nothing but fruit and vegetable juices without feeling anything much more unpleasant than hunger pains, then you can try your hand at a 3-day juice fast. 

If you discover that you actually like this fasting thing, then it’s time to move on to a water fast. Because water fasting is second only to dry fasting, it shouldn’t be done for more than a couple of days. After that, the complete lack of nutrition can cause electrolyte disturbances, which may lead to low blood pressure, abnormal heart rhythm, or even sudden cardiac death. 

But if you experience no side effects with the water fast, then you can begin a dry fast. 

However, it’s important to remember that there’s a right way and a wrong way to approach all forms of fasting. So whether you’re just starting with a juice fast or have moved on to dry fasting, prepare your body by following these simple guidelines:

  • Decrease the amount of calories you consume each day for the week preceding the start of your fast.
  • Reduce carbohydrates and load up on healthy fats.
  • Try to eliminate caffeine to reduce the chance of experiencing caffeine withdrawal headaches during your fast.

And once you’ve started your fast, be sure to take it easy. If you’re used to engaging in strenuous exercise, let it go for the duration. Performing anything more arduous than a leisurely walk will only increase your chances of becoming dangerously dehydrated.

What Happens After the Fast?

So you’ve completed your fast, congratulations!

Now you’re ready to go back to eating your old diet, right?

No, you’re not!

Doing so will not only negate whatever health benefits you may have gained by fasting but could also result in nasty side effects, including nausea and blood sugar spikes, which may lead to palpitations or anxiety.

Instead, break your fast by slowing drinking a glass of water, and continue drinking water like this every hour for the first few hours after your fast, or until you begin to feel rehydrated. Then you can begin introducing food, but be sure to start with lighter fare, like fruit, broth, or nuts. And keep your portions small for at least 24 hours after completing your fast.

Side Effects to Watch out for When Dry Fasting

With all the dos, don’ts, and warnings peppered throughout this article, you may be asking yourself, is dry fasting safe?

Honestly, the answer is, it depends.

While dry fasting is safe for healthy individuals when following the 16/8 or 20/4 schedules mentioned above, anything longer than that could lead to severe consequences. 

After all, the human body can go weeks without food, but it can die after 3 days without water. What’s more, the electrolyte abnormalities caused by prolonged fasting can lead to sudden cardiac death and strokes.

In addition, dry fasting should be avoided by certain groups, including:

  • Those taking medications
  • Women who are pregnant 
  • Those not used to other forms of fasting

However, it’s important to keep in mind that even healthy people can react badly to fasting—especially dry fasting. So listen to your body. And if you begin to feel excessively weak, dizzy, or dehydrated, stop the fast and try again at a later date.


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