Last Updated on November 9, 2023 by Fasting Planet
Through the information on this blog, you’ve learned a lot about water fasting, but admittedly, you still have some questions. Researching each of those questions individually is time-consuming, though. You wish you had a single, reliable resource you could use to find the answers to everything you’re curious about regarding water fasting.
This is the article for you! In it, we’ve compiled the most frequently asked questions about water fasting, presenting answers to each. Whether you’re curious if you can drink water when fasting for blood work, how much weight you might lose on a water fast, or how much to drink on a water fast, we’re here with all the answers.
Let’s get started!
Your Most Burning Questions about Water Fasting Answered
What Is Water Fasting?
Water fasting is considered a type of intermittent fast. While on a water fast, you eschew the consumption of food, drinking water until the fast ends.
Other forms of intermittent fasting may allow you to consume apple cider vinegar, tea, bone broth, or black coffee, but not on a water fast. Water is the only beverage you can consume.
How Long to Water Fast?
The duration of a water fast is at your discretion, but you should not stay on the fast for longer than 72 consecutive hours. Most fasters will water fast for 24 or 48 hours. Others can go for weeks, sometimes months at a time by starting and stopping water fasting.
In 1971, a man went on what is still considered the longest water fast of all time. He was 27 at the time and weighed 456 pounds. Through consuming supplements and drinking nothing but water, he fasted for over 382 days. As you may imagine, his results were quite drastic, as he lost 276 pounds. By the time all was said and done, the man weighed 180 pounds.
How Does Water Fasting Work?
How can one achieve such great results on a water fast? While we’ll talk about water fasting benefits later in this question and answer session, let’s use one of the most common reasons people go on a fast–to lose weight–to explain how water fasting works.
If you’re on the quest to drop some extra pounds, you have to consume fewer calories than you burn. While other forms of intermittent fasting let you do this, water fasting delivers quick results since there’s no food involved.
Each time you eat, you add more glucose to the body. Glucose is a type of sugar. Certain foods are more glucose-heavy than others, with carbohydrates a major culprit. When you consume potatoes, pasta, rice, and bread then, the entirety of the carbs becomes glucose. The same is true of milk, yogurt, sugar, fruits, and vegetables, even if these aren’t so carb-heavy.
Another source of glucose is glycogen. This adipose tissue triglyceride come from the skeletal muscle and the liver. If your body needs it, glycogen can be converted into glucose.
What is glucose used for, anyway? It’s our primary source of energy. If you experience a mid-afternoon slump in the middle of a workday and feel perked up after food, your glucose levels have gone up.
Through intermittent fasting, the goal is to take your glucose reserves and bring them down to zero. That’s because once your body has no more glucose to use for energy, it begins burning fat as an alternate energy source. Muscle proteins may also be used.
When you deprive yourself of food such as on a water fast, you’re not contributing to the glucose reserves within your body. Then, it’s just a matter of time before the glucose depletes. When burning fat and eating few if any calories, you can lose weight quickly on a water fast.
How Long Does It Take to Go into Ketosis on a Water Fast?
Another way you can trigger your body into burning fat over glucose is through ketosis. This metabolic state kickstarts the production of ketone bodies when you cut carbs out of your diet. Ketone bodies are a type of chemical that triggers fat to be used as a main energy source.
There are three types of ketone bodies. These are beta-hydroxybutyrate, acetoacetate, and acetone. You begin making ketone bodies when you lack insulin. As you already know, carbs become a source of sugar, glucose. When you have enough glucose in your system, your blood sugar increases. That tells your pancreas to make insulin, which causes blood sugar absorption for later energy use.
Thus, when insulin levels are lower, this absorption doesn’t happen. Fat becomes the main energy source once again.
How long you may wait to enter ketosis on a water fast depends on your glucose stores. If you have a lot of glycogen in reserve, then you may have to be patient for two to four days before ketosis happens. For experienced fasters with less glucose, you may wait up to a day, sometimes even less.
You can read more here about this topic. How to Stay in Ketosis after a Water Fast?
What Are the Benefits of Water Fasting?
We just wrote a detailed post about water fasting benefits, so we’ll recap them here.
- Cancer patients undergoing chemotherapy may notice the treatment is more effective. There’s also a possibility that water fasting can prevent the development of more tumors, although this has only been proven in animals.
- Your sensitivity to both leptin and insulin can increase. With a greater leptin sensitivity, you can ward off obesity since your hunger signals are sharper. Insulin sensitivity can control blood sugar better, keeping you healthy.
- Water fasting for as little as 24 hours at a time could reduce triglycerides and LDL cholesterol. This has the potential to prevent heart disease.
- Multiple studies done on patients with high blood pressure found that long-term water fasting can reduce blood pressure levels. These fasts must be at least 10 days though, and many are medically supervised.
- Autophagy is encouraged. This process occurs when our body eats damaged or old cell parts, sometimes even in full, so our cells are healthier overall. You could possibly avoid getting cancer through regular autophagy and enjoy a longer, healthier life.
- Like we talked about in the last sections, water fasting makes it easy to get into ketosis and lose weight.
Can You Drink Water When Fasting?
Obviously, consuming water is the basis of a water fast. Even on other types of intermittent fasts, water is an acceptable beverage to consume. These include alternate-day fasts, 16:8 fasts or other variations on this, the 5:2 diet, and the like.
The only exception is a dry fast, in which you must restrict the consumption of both water and food. On a soft dry fast, you can use water for bathing, hand-washing, brushing your teeth, and other related hygienic activities. You’re still not permitted to drink any. Hard dry water fasts don’t even let you use water for the above reasons until the fast is over.
When Fasting for Blood Work, Can You Drink Water?
If you have a blood work appointment scheduled with your doctor, he or she might ask you to fast for upwards of 12 hours ahead of the testing. Sometimes these requested fasts are shorter, only eight hours.
While you should always confirm as much with your doctor, you’re generally not allowed to eat any food when fasting for blood work. Beverages are also not allowed, but water should be.
You can plan for your blood work fast by going to bed early so you sleep through most of it. By eating a nutritious and filling meal before the fasting period begins, you may not feel super hungry. If you do, sipping water can fight off those uncomfortable pangs.
How Much Water Should I Drink While Fasting?
Whether you’re water fasting by choice or for a medical test, how much water should you drink every day? It’s recommended you consume between two and three liters a day. For women, that’s about nine glasses of water and for men, it’s 13.
It’s important to stick within those guidelines during your water fast. Drinking too much water can lead to hyponatremia, also known as water intoxication. Although water is usually good for you, when you overdo it, your bloodstream’s sodium levels plummet and your cells can flood. It’s possible to fall into a coma, have seizures, and even die from hyponatremia.
To make each of your glasses of water last, sip them rather than swallow them all down at once.
How to Prepare for a Water Fast?
Water fasting is not just a decision one makes that same day. You need to wind down your food consumption to ready your body for what’s to come. That’s true whether you’re water fasting for 24 hours or even less.
To do that, begin your preparations a week before the fast. You want to slowly reduce your food consumption, cutting down on both portion sizes and even how many meals you eat a day. As you get to three days before the water fast, begin incorporating more liquid-based foods into your diet. These include smoothies, fruit juices, and vegetable juices.
When your fast comes to an end, reintegrate the above liquids into your diet. It may be a day or two before you feel ready for a regular meal. When you do eat solid foods again, start with small quantities, just as before.
Going slow and steady like this helps you avoid refeeding syndrome post-fast, which can be deadly.
Can You Drink Water When Fasting for a Glucose Test?
If you’re getting your blood glucose tested by a medical professional, this can happen one of two ways: through fasting or randomly. Assuming you’re told about the test, your doctor will instruct you to begin an eight-hour fast.
You may have to cease taking some medications for that period, as those can interrupt results. So too can eating, as carbs and other food sources deliver glucose to our bodies. Thus, no food is permitted, and the same goes for caloric beverages. You can have water though, so drink up!
Like we recommended when fasting for blood work, adjust your sleep schedule so you’re not awake for most of the fasting period to get through it easier.
What to Expect When Water Fasting?
Water fasting is admittedly more difficult than other kinds of intermittent fasts because no food is allowed. We would advise you to try a simpler fast first before a water fast, and even then, to keep your water fasting short the first few times.
While fasting, here’s what you may experience.
- Hunger: Naturally, when foregoing food like on a water fast, you will get hungry. This may start off as manageable at the beginning of the fast but get distracting and even overwhelming later.
- Mental fog: As glucose stores disappear in your system, your energy goes with it. You may find it hard to concentrate or do any meaningful work on a water fast. It might be best to schedule the fast for a weekend or another period when you have downtime.
- Physical exhaustion: Again, without energy, you’ll have little motivation to get up and do much of anything. You should try to exercise if you can, but don’t push yourself if it truly feels like too much.
- Difficulty sleeping: Although you’re very tired, your rumbling belly keeps you awake. This is normal for new fasters, but it may not last. The Sleep Doctor, Michael J. Breus, Ph.D cites data that mention how short-term intermittent fasts could make it easier to sleep. We may even be able to sync with our circadian rhythms more effectively through fasting.
How to Deal with Hunger When Water Fasting?
You’re super-duper hungry. Not only could you eat a horse right now, but you’re beginning to find even non-edible items appetizing. If you’re on a longer water fast, how do you get through the next day or two when you’re already ultra ravenous?
Here are some tips.
- Drink water: Seriously, you have plenty of it to go around, so you might as well use it. While water cannot replace the satiety that food brings, enough of it does make your belly feel full, at least for a little while.
- Go to sleep: If you’re not awake, you won’t feel as hungry. Like we said above, sleeping on an intermittent fast isn’t necessarily easy, but it can improve your sleep quality with time.
- Do some exercise: As you move your body through yoga, walking, or even some light cardio, you stop thinking so much about your hunger.
- Try another immersive activity: Besides exercise, any activity that requires your full attention is a good one to try. Watching movies and listening to music can work for some, but for others, they may find they get distracted by their hunger quickly. Whether you sew, play video games, or do something in that same vein, you’re busying your mind and your body. You could even forget about your hunger for a while.
Is It Okay to Drink Water When Fasting for a Cholesterol Test?
We’ve talked about whether you can consume water before taking a blood test and a glucose test. What if you’re due in for a cholesterol test? Can you drink water then?
The fasting period is generally a little longer for cholesterol tests, roughly nine hours at the shortest and up to 12 hours at most. Well, that is, if your doctor asks you to fast at all, as it’s not always necessary.
Like with the other tests we’ve discussed, both caloric beverages and food are barred, but water is not.
How Much Weight Can You Lose in a Week When Water Fasting?
We talked about how water fasting works earlier concerning weight loss, but we didn’t touch on how many pounds you can expect to shed. If your fast lasts 24 to 72 consecutive hours, then you could lose two pounds per day. That can lead to as many as six-ten and more pounds lost in a week.
Where does this weight loss come from? Your body burns fat during a water fast, and when you restrict calories, that promotes even greater weight loss. Your body will take from your muscle mass, carbohydrates, and even water weight to give you a lower number on the scale.
Can I Drink Water When Fasting for an Ultrasound?
Expectant mothers receive ultrasounds, but this medical testing can be useful for other abdominal conditions as well. For example, ultrasounds can diagnose appendicitis, liver cancer, kidney stones, pancreatitis, hernias, gallstones, and blood clots.
Consuming food up to six hours before an ultrasound can alter the appearance of your gallbladder, skewing results. The same can happen with sugary beverages or those with a lot of fat. That’s why it’s best to stick to water.
You can even enjoy tea or black coffee ahead of your test, giving you plenty of versatility with your beverages.
How to Keep Muscle While Water Fasting?
Weight loss from a water fast can look like victory on the scale, but it’s often at the expense of your muscle mass. Can you preserve your muscle mass while water fasting or doing any other intermittent fasts? Yes, you can, through exercising.
Here’s how it works. The mammalian target of rapamycin or mTOR, a kinase, helps our muscles get bigger through a process known as protein synthesis. This is when your body takes the proteins in your system and makes them into muscle tissue.
According to Peter Attia, MD, our bodies produce less mTOR on an intermittent fast. However, resistance training and other physical activity can boost mTOR and mTORCI1 even without amino acids or growth factors.
The mTORCI1 can hold onto some amino acids, saving them for our muscles so they don’t lose as much mass.
You can read more about this subject here: Exercising While Fasting: A Good Idea or Not?
What Are the Warning Signs of Water Fasting?
Water fasting can be exponentially beneficial for the body, but it does carry with it some risks. These include the following:
- Affecting preexisting conditions: If you have an eating disorder, diabetes, or gout, it’s recommended you do not go on a water fast without your doctor’s permission and supervision. It’s believed water fasting can worsen eating disorders, boost your chances of diabetes-related side effects, and boost uric acid that causes a gout attack.
- Could cause orthostatic hypotension: If you stand up on your water fast and feel woozy and even like you could faint, this is orthostatic hypertension. Your blood pressure decreases at such a fast rate the above symptoms manifest. This can make getting through a water fast difficult.
- Dehydration: One of the riskiest side effects of water fasting is dehydration. You get about 30 percent of your regular water needs through food, so it is possible to become dehydrated even when drinking water. If you feel especially unproductive, your blood pressure drops, and you have constipation, headaches, nausea, and dizziness, you may be dehydrated. At its most serious, dehydration can be fatal.
Conclusion
Water fasting is a great way to lose weight, trigger autophagy, enter ketosis, and cleanse your system. This question and answer guide should have hopefully addressed some of your most burning questions about water fasting. You can now make a smart, safe decision for your health with a water fast. Good luck!