Dry Fasting: Safety, Risks, Dangers & Side Effects

Is dry fasting safe? Won’t you get dehydrated? Can you get a heart attack? Don’t worry; these hard questions have easy answers if you enjoy a good dose of science. 

Just to be clear, the dry fasting we’re talking about means complete abstinence from food and water. (Not the celebrity dry fast where you only get liquid from fruit and vegetables, although that isn’t a bad idea.) 

Dry fasting means absolute fasting: nothing enters your mouth for a set amount of time. A dry fast can range anywhere from 10 hours to 11 days, with the longest recorded dry fast being 18 days. 

Shocked that people don’t drink water not just for hours, but for days? Turns out dry fasting has been around for thousands of years; in the times before fire or light, people stopped eating when the sun went down and ate when the sun came back up. Every major faith has some practice of extended hours of dry fasting, although they also warn against dry fasting if you’re unwell or unfit. 

Is dry fasting safe?

Dry fasting for extended periods should only be done by advanced fasters or under medical supervision. Dry fasting without the proper preparation or protocol, or if you’re in a high-risk category, can also be dangerous. For most people, however, dry fasting for short periods is safe and encouraged for increased wellbeing. 

Every year over 1.5 billion Muslims dry fast for a month during the daylight hours of Ramadan, which, depending on the region, can be anywhere between 11–22 hours. Countless studies have been done on the many health benefits of those who dry fast during Ramadan, proving that it’s far from dangerous.

Of course, some people should not dry fast under any circumstance, or only under strict medical supervision, such as:

  • Pregnant women 
  • People with medical conditions (diabetes, kidneys issues)
  • Injured, stressed, or weak people

If you’re one of the above, you’re taking a risk—so don’t even try. Dry fasting is stressful for your body and should be approached with respect. But if you prepare for a dry fastdry fast according to protocol, and break the dry fast properly, dry fasting can be easy and safe. 

In fact, dry fasting is the most natural, safest type of fast there is. You dry fast every day as you sleep because your system can finally focus on healing when you stop eating. That’s the reason you lather on those expensive Korean face creams before bedtime because bedtime is when your body repairs itself.

Most of the world’s health problems today exist because humans never stop munching and guzzling, and when we’re eating, 80% of the body’s energy is directed towards food consumption. Humans stopped eating and drinking for thousands of years when it got dark because we couldn’t see. Today when it gets dark, we get a cheese platter.

The practice of intermittent fasting also follows this idea: to extend your overnight fast and give your body a more extended break to focus on healing. Water fasting also goes along with this same idea. No food to digest equals more time to heal, clean up and repair. No water makes your body even more efficient at self-healing, and the regular practice of dry fasting can help you reverse aging, lose weight, and have many other health benefits.

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What are dry fasting safety concerns?

The biggest safety and health concerns about dry fasting are probably about these subjects:

  • Dehydration 
  • Prolonged dry fasting causes death 
  • Muscle mass and vital organs 
  • Kidney health 

Dry Fasting Causes Dehydration 

Dehydration during dry fasting usually tops the list, a reasonable assumption and one that isn’t far off the mark. Dehydration means your body is losing more fluid than you take in and upsetting the balance of minerals in your body – which is almost exactly what happens in a dry fast. 

So yes, you do get dehydrated in a dry fast and even have some of the symptoms like weakness, tiredness, headaches, and less pee. This mild dehydration is, however, a good thing. This stress in your body forces it to change its metabolism and adapt to its environment. 

Water is vital for all life and makes up over 70% of your body, but you’re not getting exogenous water when you’re dry fasting. So how does your body get water? Your fat cells are 90% water. 100 grams of fat creates 110 grams of metabolic water. Your body can make up to 1 liter of water from breaking down your fat cells. 

This 1989 study carried out in Malaysia during Ramadan, which is intermittent dry fasting of about 12-14 hours, shows that the water content in your body remains the same during the entire period of dry fasting. 

Another pioneering 5-day dry study on dry fasting undertaken in 2013 found that even after 5 days, none of the 10 participants showed any signs of dehydration. The study also could not explain ‘insensible water loss’ during the dry fast as the urine discharge of patients was still high even after 5 days, although they were not drinking water. 

The science behind dry fasting is just catching up. Autophagy which explains much of how your body makes water during a dry fast only became widely known in 2016, when the scientist who researched it won a Nobel prize.

Read more on dehydration during dry fasting and why it could save your life.

Dry Fasting Causes Death 

In other words, the dehydration caused during dry fasting will lead to death after 3 days. There’s a myth that you will die after 3 days of not having water which is simply untrue. When you dry fast, your body is actually making water from combining fatty acids with oxygen to make H20 (and every cell does this!). So unless you’re dry fasting inside a car booth and running out of air, your body can make enough water for you to survive. 

Our bodies are intelligent and highly adaptable with reserve stores (even your skin has water reserves) and hold up to 4 pounds (2 kgs) of water. Your skin also becomes highly porous during dry fasting and can absorb moisture from the environment when necessary.

The human body can survive without water for 12 days in comfortable conditions (in the mountains, near waterfalls, and rivers)… From a physiological point of view, the body doesn’t experience a significant lack of liquid during fasting because up to 1 liter of endogenous (metabolic) liquid is released for every kilogram of broken down adipose mass (or glycogen) daily.

Dr. Sergey Filonov

Dry Fasting Causes Muscle & Vital Organ Degradation 

Another concern you might have on dry fasting is whether you will start to waste away? Does dry fasting cause muscle loss? In the absence of food, will your vital organs be used as food? 

Dry fasting is unlike specific unhealthy calorie or food-type restriction diets, or even water fasting, which mimics the effects of eating into the muscles and vital organs if done for prolonged periods. 

Unlike nutrient deficiency or starvation, the lack of water in dry fasting activates a shift of metabolic pathways in your body and only eats into the unhealthy, unneeded, damaged cells and tissues, sparing essential tissues such as muscles and vital organs. 

The science behind dry fasting shows that metabolic changes autophagy, stem cell regeneration, and human growth hormone secretion cause internal cellular process in your body, which actually strengthens and heals your muscles and organs, not destroys them.

Even when you dry fast for weight loss, you won’t have loose or saggy skin because the process of autophagy consumes the dead skin cells. 

Dry Fasting Damages Your Kidney 

Most of the water we ingest daily is unhealthy, with heavy metals, toxins, pesticides, chlorine, salts, and iron ions, all of which the kidney needs to filter and clean. Even filtered water can be problematic and needs to be changed often to avoid waste and bacterial microflora growths. 

Dry fasting is actually a complete rest for your kidneys, not more work. One study found that the concentration of crystal-forming in urinary secretion actually decrease during dry fasting. Without water that needs to be cleaned and filtered entering the body, the kidneys actually have time to heal. Dry fasting has been seen to actually improve and cure several kidney diseases. Kidneys are quite strongly linked to the liver, so a liver cleanse is always suggested before a dry fast. 

Dry Fasting Dangers, Risks & Side Effects 

The complications of dry fasting increase with the length of time you plan to dry fast and can be accompanied by specific unpleasant side effects. But if you start off knowing ahead of time what to expect, and if and when you should be concerned, then you’re in the safe zone. 

Some basic safety rules of dry fasting: never enter a dry fast dehydrated, binge eat after a dry fast, or attempt a 3 day dry fast as a fasting novice. But even though you’ve taken all the preparation measures, you’re sometimes not aware of your body’s actual health condition. 

Here are some of the dangers and risks of dry fasting so you can spot them if they happen and attend to them if needed. 

Dangers of Dry Fasting

  • Vertigo/dimmed vision 
  • Blackouts
  • Nausea, vomiting, regurgitation 
  • Palpitations 
  • Heart pain
  • Severe dehydration

Vertigo/Dimmed Vision

Vertigo or dimmed vision can happen due to suddenly getting up from a lying or seated position. The imbalance in your lowered blood pressure and blood thickness can result in an uneven redistribution of blood. 

Taller people tend to experience this more, just a measure of gravitational pull. The solution is to simply get up slowly and hold on to walls or the back of a chair for support. However, if you’re an active person generally and spend time outdoors, this is less likely to affect you. 


Fainting or blackouts are also possible from this imbalance of fluids and a symptom of dehydration. If you’ve prepared well for your dry fasting and have taken all precautionary measures, this can generally be avoided.

Nausea, Vomiting, Regurgitation 

Excess toxins in the body can cause you to become nauseous, and the best way is to move around more – specifically to get out in nature. According to Dr. Sergey Filonov, your body needs 3 times more fresh air during dry fasting. This excess air also helps increase healthy circulation in and out of your lungs, which is an effective method of removing toxins, especially if you’re fasting for more extended hours—since your body can’t remove them fast enough during the dry fast. 

Walking, when nauseous, is highly recommended and much better if done for 3 hours. Movement makes the organs work better and improves circulation, which always helps you feel better. If you don’t mind breaking your fast, you can take a teaspoon of ginger lemon juice. If not, try inhaling the scent of lemon oil or peppermint oil. 

If you’re starting to experience sour regurgitation, you likely have digestive issues, and your stomach is poisoning you. Immediately drink water and induce vomiting to do a cleanse of the toxins out of your body. If this persists after doing this up to 3 times, or you have unrelenting heartburn, drink still water with sorbent. 

Green or black vomit means your liver is highly toxic and is being cleansed and healed. It’s not something to worry about, and it’s best to wait till this passes. 


The pulse rate can become erratic during dry fasting, sometimes dropping down to 40, or up to 100, neither of which is cause for concern unless accompanied by weakness or pain. If your pulse rate goes over 120, then stop fasting immediately. 

Heart Pain

If you have persistent arrhythmia or heart pains, try calming yourself down first using meditation, self-hypnosis, palpitation, or acupressure. If these don’t work, you may need to use an electrocardiogram to restore the heart’s rhythm. 

Severe Dehydration

Going into a fast without hydrating properly beforehand can be dangerous. Dehydration during a dry fast could lead to kidney stones, seizures, electrolyte imbalance, low blood pressure and low blood volume. If you went into the fast mildly dehydrated to begin with, had alcohol or over-exerted yourself physically, or started the fast in any way without taking all preventive measures, and experience dizziness or faintness, then break the fast.

Side Effects Of Dry Fasting 

  • Hunger 
  • Weakness
  • Chills/fever
  • Cold 
  • Bad breath 
  • Headaches 
  • Disturbed sleep 
  • Body aches 
  • Toothache 
  • Poor skin 
  • Muscle pain 
  • Anxiety/nervousness 


The hunger that happens during a dry fast is more a result of habit than actual hunger. Most regular dry fasters report not feeling hungry during dry fasting and less starvation than water fasting. (I definitely agree!) Some fasters feel that brushing their teeth will help and with a strong desire to brush their teeth, but this could activate stomach acid, which isn’t beneficial for healing. Better to do oil-pulling if you feel like brushing your teeth. 

Hunger can usually be avoided if you don’t overeat before the fast and have smaller meals with more fat and fewer carbs. Carb cravings is typically the cause of hunger. Cleansing your colon properly before will also help to lessen hunger pangs. 

If you dry fast for 4–5 days, there’ll be no more hunger. Even after 36 hours, the hunger usually dissipates. But you also tend to think about food when dry fasting, so decide you’re not going to eat, and you won’t be tempted. Also, avoid situations where there is food around you—or you might end up with irritation, sleep disturbance, headaches, or heartburn. Best to keep busy and avoid situations that are too stimulating. You can also try breathing exercises to aid hunger. 


Weakness is natural during dry fasting because you lack energy. The first 24 hours is usually easier, but you might experience more weakness on the second day, to the point where you can’t get out of bed. If you’re tired and weak, rest as much as you need. 

Going for walks, however, is much better for weakness. Getting fresh air and moving your body in nature, especially walking barefoot on the ground, will help you rejuvenate and re-energize. Having a massage, sunbathing, and bathing are also other rejuvenating options for weakness. 


The biological changes in your body raise your body temperature and increase your metabolism, and this will usually cause an internal chill, making you feel cold. However, some experience handling hot too, but chilliness is more common.

Sometimes this can turn into a fever; mostly, it’s more internal heat that isn’t detected outside your body. If you’re feeling cold, simply dress up with more layers and keep yourself warm. You can also take baths, do a soft dry fast, or take walks to warm up. 


The release of toxins into your body naturally will weaken your system. Colds don’t usually occur, but if you’re feeling sick, avoid exposure to the cold and try and relax and it will usually go away. An option is also to inhale steam with a few drops of eucalyptus oil. If the cold persists, then cut your fast short. 

Bad Breath

Bad breath results from toxins and chemicals being released by the body, such as compounds that haven’t been fully oxidized. The smell of acetones can also be quite strong from the ketosis process in your body. Saliva consistency and quantity in the mouth and any food debris left in the mouth can also— proper preparation before dry fasting will help to lessen this. 

Usually, by the 2nd or 3rd day, the smell of the breath can become quite bad, especially if you’re new to dry fasting as there are more toxins in the body that need to be released. On these days, your body hits the acidotic crisis, which changes the acidity level of the system and triggers most of the destruction of toxins and damaged cells, which can cause foul smells. 

Most of these toxins will be destroyed internally, but you can assist the lungs in expelling more toxins by increasing your physical activity, anything that gets your metabolism moving. 

Go here for more on the mechanism behind dry fasting bad breath and ways to treat it. 


Headaches are also usually a sign of contaminated blood and often happen if you’re indoors in small places or in vehicles where there isn’t enough space to exhale air and circulate air. If you experience headaches, try purifying and cleansing your liver with a juice fast, food or herbal medicines, or an enema before the next dry fast. 

Headaches happen just before an acidotic crisis occurs, as that’s the highest point for the toxins in your blood. Walking in nature and taking deep, long breaths will help to ease headaches so you can breathe those poisons out. 

Disturbed Sleep 

Dry fasting can cause sleep issues; sometimes you’ll feel very sleepy, other times you won’t be able to sleep at all and can only get 4 hours of sleep a day. If you’re feeling fatigued, do get plenty of sleep as the healing benefits happen when you sleep. If you’re not sleepy, make sure you go for long walks, even up to 4-5 hours, which should help your body feel more tired, and you’ll get an even better sleep afterward. If you can’t sleep even after 3 days, then it’s best to break your fast. 

Body Aches 

Pain is not a reason to worry; in fact, it’s a good thing and usually short-lived. The reason for pain in a specific area is the damaged tissues in that area start to heal. Old injuries can suddenly start up again, but this means they are getting sorted. 

Sometimes pain can come from a disease that has yet to appear and show itself but is being attended to by the healing process – such as a joint pain that was the early signs of arthritis. 

Back pain can result from damaged liver or intestines as toxins can leak out into blood vessels near the spine and might cause your nerves to hurt. In all cases, the pain will subside, so just wait it out. You can also try a bath with Epsom salts or rub some sesame oil on the area to relieve some of the pain. 


You should always treat your teeth before dry fasting, especially if you have gum disease. Get your teeth in good condition and make sure you’ve done your twice-yearly dentist visits. 

If you’re experiencing bleeding, pus, or pain, rinse your mouth with water mixed with lemon juice or dry white wine. Oil pulling can also help to remove some pain. 

Sometimes you might get a compulsive need to brush your teeth, but do be wary as the composition of saliva changes when you’re dry fasting and can become corrosive. There is usually a protective enamel over teeth during a dry fast, so best to let your teeth take care of themselves and not interfere.

Poor Skin 

Ideally, healthy people can get pimples or boils when dry fasting, simply due to the toxins showing up on their face. If it’s a concern, you can use potato skin, grated potatoes, or ice or apply coconut oil overnight to lessen their appearance. Sometimes the skin can get eczema or look pale, dull, or extremely dry. All of these usually go away after you end the dry fast. Do make sure you eat healthy and nutritious food after your fast and hydrate well. I’d also recommend the Fruit Fusion multivitamin and mineral powder to give your body all it needs and keeps you in keto for the healthiest exit out of a fast, and for glowing clean skin (a reflection of your gut and liver health) I like this detox and superfood green juice. 

Muscle Pain 

Old sports injuries can cause pronounced pain during dry fasting. These are being healed, so don’t worry. You can use a small amount of ointment that has snake or bee venom or shilajit— once or twice daily— to help with the pain. You can also rub the area with sesame oil and use a heated pad. Be careful as the body will digest the creams, oils, or anything applied to your skin. 


Toxins can irritate nerves that are damaged and make you edgy. All the cleansing can lead to emotional breakdown and anxiety. Be prepared and do calm or relaxing activities. 

Hopefully, you’re now feeling safe and informed and eager to begin your dry fast! For more on how to maximise the powers of dry fasting to get fitter, healthier and age backwards, check out my new video course, 25 Again! The Dry Fasting Lifestyle For A Younger, Slimmer You

TDFF Course Package e1667423875466



***Disclaimer: I am not a doctor/ physician, and although I have a bachelor’s degree in Biomedical Science, I cannot and do not hold myself to be a medical professional (“Medical Provider”). This article does not contain medical /health advice. The medical/ health information here is for general and educational purposes only. It is my opinion, based on my research and personal experience, and not a substitute for professional advice by your health care provider. Please consult with a professional before acting on the information here, and do not disregard medical advice or delay seeking medical attention because of anything you read in this article. THE USE OR RELIANCE OF ANY OF THE INFORMATION ON THIS WEBSITE IS SOLELY AT YOUR OWN RISK.***


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