Can You Drink Water While Fasting?

Intermittent fasting is alternating between eating and fasting during specific hours of the day. You can drink water while fasting, but you should be under medical supervision if you'd like to fast for more than one to three days.

Recent research has demonstrated the benefits of intermittent fasting. Unfortunately, understanding what you can eat or drink during a fast can get confusing. One of the most common questions is: “Can you drink water while fasting?” 

The answer to this isn’t straightforward and depends on factors such as the purpose and the type of your fast. This article will explore whether you can drink water during certain fasts and what other factors you should be aware of.

A widespread weight-loss practice includes intermittent fasting, in which you alternate between eating and fasting during specific hours of the day. While regular diets focus on what you eat, the goal of intermittent fasting is to monitor when you eat.  Research has found this an effective method for managing weight.

A 2015 study found that eating frequently is linked to obesity or being overweight. According to the study, people who ate more than four times a day were 50% more likely to be overweight or obese than those who ate a maximum of three times a day. The study involved more than 18,000 American adults over 20.

One of the most common intermittent fasting practices is eating during an eight-hour period of your choice — typically from 10 am to 6 pm — and fasting for the remaining 16 hours. This intermittent fasting leads to a period of zero calorie intake after your body has burned the calories you ate during your last meal, causing your body to break down stored fat — a process called metabolic switching.

Research shows intermittent fasting reduces the risk of several chronic conditions, such as age-related neurodegenerative diseases, inflammatory bowel disease, and cancers. Intermittent fasting also enhances brain functions, especially verbal memory, and burns body fat without sacrificing muscle mass. Since intermittent fasting focuses mainly on limiting your calorie intake, though, there’s no restriction on drinking water.

Water fasting involves drinking only water while abstaining from solid food for a period of time generally lasting one to three days (or longer, if you are under direct medical supervision). There are many reasons to go on a water fast. A primary reason to start is to reduce caloric intake to lose weight.

Research suggests there are some benefits of water fasting. A 2021 study involving 45 healthy participants found that water-only fasting reduces the risks of metabolic disorders and inflammation-related conditions. According to the study, fasting slows down your aging process and causes a noticeable reduction in body weight, waist circumference, and body mass index (BMI). Water-only fasting also has other health benefits.

Lowers your blood pressure

A 2014 study involving 174 participants with hypertension found that water fasting helps lower blood pressure. According to the study, medically supervised water-only fasting reduced the participants’ blood pressure considerably. At the end of the study, the participants did not feel the need to take any other medication for their hypertension.

Could improve heart health

According to research, water-only fasting lowers the risk of cardiovascular diseases. One such study involving 30 healthy participants found that water-only fasting increases the red blood cell count, human growth hormone, and hemoglobin. The study also recommends frequent short-term fasting as a method to counter the risks of metabolic diseases. Still, more research is needed to understand the long-term effects of water-only fasting on heart health.

Improves kidney function

A 2018 study found that water-only fasting improves kidney function, reduces oxidative stress, and lowers bad cholesterol (LDL cholesterol) levels. Unchecked oxidative stress causes a spike in the number of reactive molecules in your body that can lead to cell and tissue damage.

Some medical procedures require you to be on a water-only diet for roughly eight to 12 hours before the procedure. This ensures that you’re on an empty stomach to minimize the risk of any complications during surgery.

You should also fast before some medical procedures to prevent lung damage. Under normal circumstances, your body prevents the contents of your stomach from entering the lungs, but anesthesia limits your body’s ability to do this. When food or stomach acids enter your lungs, that can lead to infections and lung damage.”

While most health experts suggest you can drink water while fasting, that depends on your purpose. Those who fast for religious purposes may forgo water as well, even if that is not the healthiest decision.

Others may fast for their health. Fasting burns calories and helps keep your weight in check. A lot of research indicates fasting is good for health, whether that involves intermittent fasting, water-only fasting, or both. However, the long-term effects of such fasts are still to be understood. Your body does not get enough calories when you fast, and this could cause: 

• Dehydration
• Inadequate electrolyte levels in your body
• Heart arrhythmias
• Lower metabolism
• Constipation
• Erratic blood sugar levels
• Lightheadedness

If you think a water-only fast is not for you, there are other options you can explore. In addition to water, you can add other clear liquids to your diet. These include:

• Fruit juices without pulp
• Sports drinks
• Carbonated drinks
• Tea and coffee
• Clear broths

On the other hand, you may wish to avoid items such as milk and orange juice, as they contain more nutrients and may take more work for your metabolic system to break down.

If you want to lose weight, check with your doctor whether fasting is safe and what you can eat or drink during such fasts.

In addition to children and teens under 18, the following people should avoid fasting:

• Pregnant women
• Women who are breastfeeding
• Individuals with diabetes
• People with a history of eating disorders