How to Start a Water Fast + Benefits and Risks

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Woman drinking water

Are you drinking 6 to 8 glasses of water every day? We often hear that this is important for maintaining good health. However, what if you follow that guideline without eating food? That’s what a water fast is all about. People learn how to start a water fast for different reasons. These fasts can provide benefits like weight loss, and body detoxes. It also might help people with health problems like obesity and high blood pressure. Health experts generally recommend doing a short-term fast that’s up to 24 hours. This can provide many benefits like causing your body to go into the state of “ketosis” like the keto diet.

As always, it’s important for the water fast to be effective AND safe. For example, if you have serious health conditions like diabetes and heart disease a long-term fast could cause various health issues. Other people might also have problems with long fasts like seniors and kids/teens. Water fasting could be considered an extreme diet since all you’re consuming is water. So as always you should talk to your doctor before you go on a water-only diet. This is especially true if you have health conditions or are taking certain prescription drugs during the fast.

What Is a Water Fast?

Fasting has existed for a very long time. For example, people in certain religions have been fasting for hundreds of years. This is a time they skip eating and focus on their spiritual life.

People have also been fasting for health reasons for over a century. It started during the early 20th century (the 1900s). The famous liquid diet known as the Master Cleanse was designed during the 1940s. It was created by a man who followed alternative medicine.

Today you can pick from several detox diets. They claim that they rid the body of wastes/toxins, boost weight loss, and provide other benefits that increase overall health. 

That brings us to water fasting. As the name suggests you drink water and only water. Water is a drink but not a beverage. You’re not allowed to consume other drinks like:

  • Juice
  • Tea
  • Smoothie
  • Coffee
  • Sports/Energy drinks
  • Shake
  • Alcohol

You can’t even drink so-called zero-calorie beverages like green tea and black coffee. Besides that, you also can’t eat any solid food while on the fast.

Water fast usually lasts for one to three days. Health experts warn against doing a water fast for more than 3 days. The only exception is if your doctor gives you a thumbs up and supervises your long-term fast.

Besides water fasts, there are also some variants. For example, there are detox diets that feature similar drinks like lemon water.

The main difference is they can last up to a month or more. Another difference is these detox diets also allow you to consume healthy food while on the diet.

Before starting a water fast, you should talk to your doctor. They should know any medical conditions you have, which could be affected by the fast. You should also inform them of all over-the-counter (OTC) and prescription medicines you’re taking. These factors could trigger unwanted side-effects.

How to Start a Water Fast

The basic mechanics of water fasts are basic. However, that doesn’t mean it’s a walk in the park. When you’re on these fasts you can’t eat/drink anything else besides water.

Experts recommend that you drink 2+ liters (0.53 gallons) daily while on this diet. However, it’s even better to drink 3 liters daily. The reason is since you won’t be consuming food you won’t get the H2O from them. For example, apples, tomatoes, and lettuce are high in water.

Is this your first water fast? If so then it’s important to slowly prepare your body for the event. You can do this by dropping calories for a couple of days before you start your fast. This will prevent your body from experiencing shock when you begin.

After you’ve completed the water fast you might feel like you want to eat a huge meal. This is a bad idea. That’s because you could have some negative side-effects like nausea or digestion problems.

You could even experience something related to big changes in your body’s metabolism. You’ll want to avoid that so try to go easy on the comfort foods when breaking your fast.

Here’s a better approach. Just like easing into the fast, you should also go slowly when going off the fast. For example, add some non-zero calorie beverages like juice or milk. Then add some small snacks/meals. It should take about 3 days for you to start eating full-size meals again.

This process can be tough after you haven’t had solid food for 1-3 days. However, it’s critical if you want to avoid possible health issues related to eating super-sized meals right after your water fast.

If you have any questions before, during, or after the fast make sure to contact your doctor. They can provide some advice to help you stay on track.


1. Risk of disease

Water fast can help to lower your risk of serious diseases. They include heart disease and cancer. Studies show that water fasts can lower cholesterol, which is important for disease prevention.

2. Weight loss

Studies show that a low-calorie diet that lasts for 24+ hours can cause weight loss. Yes, these diets are usually for just 1-3 days. However, a water-only diet makes your total calories: zero.

One caveat to keep in mind is the weight will mostly be in the form of water and stored carbs. This is different from burning fat, which is equal to 3,500 calories per pound.

Here’s why. It takes a couple of days for your body to begin burning fat. It first burns all glucose (blood sugar) and stored carbs.

3. Blood pressure

Water fast might help to lower blood pressure. The main reasons are you’ll be drinking water and eating/drinking less salt. This helps to decrease blood pressure.

One X-factor is you’ll probably be fasting for 1-3 days. So, the drop in blood pressure will be lower than long-term fasts that can produce larger blood pressure drops.


1. Dehydration

How is this possible when you’re only drinking water? Fun Fact: people usually get at least one-fifth of their water from food. So, here’s the thing. When you don’t boost your water consumption during the fast, you’ll be getting less water than usual. Amp up those 6-8 glasses!

2. Fewer Nutrients

You won’t be getting much OR many when you just drink water. When you’re consuming zero calories that means you’re missing out on lots of:

  • Amino Acids
  • Electrolytes
  • Enzymes
  • Fatty acids
  • Minerals
  • Probiotics
  • Vitamins

In other words, an all-water diet is low-nutrient. It’s important to start adding them back to your diet after you learn how to start a water fast.

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