The 2 Day Water Fast: A Complete Guide [How To + What To Expect]

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Although it seems like intermittent fasting diets are a recent health trend and weight loss strategy, fasting has been practiced for thousands of years in one way or another. 

The most common intermittent fasting diets involve time-restricted eating patterns, such as 18/6 intermittent fasting, wherein each day includes an 18-hour fast and a six-hour eating window, or a stricter intermittent fasting 20/4.

But, there are also intermittent fasting diets that use an alternate day protocol, by fasting 24 hours every other day and eating regularly on the off days.

This type of approach to eating, health, and weight management can be extended to a 2 day water fast, a more extreme version of fasting where you do a 48 hour water fast occasionally or periodically.

In this article, we will discuss how to do a 2 day water fast, tips for fasting for 48 hours, and how to prepare for water fasting for 2 days.

We will cover: 

  • What Is a 2 Day Water Fast?
  • Is a 48 Hour Water Fast Safe?
  • How to Prepare For a 2 Day Water Fast
  • How to Do a 2 Day Water Fast

Let’s dive in! 

A glass of water and an alarm clock.

What Is a 2 Day Water Fast?

A water fast involves abstaining from all food and caloric beverages and only drinking water for the duration of the fast.

Intermittent fasting is a mini version of water fasting that might involve extending your overnight fast through the next afternoon and eating your first meal mid-day.

Some people do 24-hour water fasts or even 36-hour water fasts as an ongoing diet plan to help support weight loss rather than restricting calories to a moderate amount every day.

A 2 day water fast is an even more extreme protocol of water fasting, requiring the complete abstinence of all food and caloric beverages for a full 48 hours. 

A 48 hour water fast is often performed by people who want to work up to 5-day water fasting or fasting for a week.

Three empty plates with the word fasting written above them.

Is a 48 Hour Water Fast Safe?

Although any type of fasting can potentially support weight loss and may improve other markers of health, most medical providers say that it is not necessary to do prolonged fasting to achieve many of the reported and perceived benefits of fasting.

With that said, 2 day water fasting teeters right on the edge of what most people can safely attempt on their own to maximize the benefits of fasting and an overly aggressive and potentially unsafe fasting routine that requires medical guidance and supervision.

However, it is still highly recommended that you speak with your healthcare team to discuss the potential risks and important safety considerations before doing a 48 hour water fast.

Medical supervision will help ensure that water fasting for 2 days does not put your health in danger, and your doctor may have specific concerns or recommendations for safer diet and weight loss practices.

Long-term fasting can result in dangerous electrolyte and blood sugar imbalances or deficiencies that can potentially affect your cognition, decision-making ability, focus, nerve conduction, fluid balance, muscle contraction, and even heart rate and rhythm.

Pouring a glass of water.

How to Prepare for a 2 Day Water Fast

When people first take interest in 2-day water fasting, they often ask, “Can I water fast for 2 days?”

This question can actually entail two underlying sub-questions: How do you do a 48-hour water fast from a physical or practical standpoint (what can you eat, etc.), and can I water fast for 2 days from a mental standpoint (will I be able to control my appetite, cravings, hunger, etc.)?

Both aspects are important for success during your 2 day water fast, so it’s helpful to begin physically and mentally preparing yourself before the actual water fast begins.

To physically prepare for a 48 hour water fast, it’s often helpful to try shorter water fasting protocols, such as time-restricted intermittent fasting with reduced eating windows.

For example, you might try 20/4 intermittent fasting for a week or two leading up to your 2 day water fast. This is a time-restricted eating approach that involves prolonging the overnight fast for a full 20 hours every day and then only eating during a four-hour window.

Or, you might try doing a 24 hour water fast the week before your 48-hour water fast.

These “mini“ fasts can help your body rehearse some of the physical sensations that you will experience during a 2 day water fast so that it won’t be a complete shock to the system once you cease all energy intake for a full two days.

An empty place setting symbolizing the 2 day water fast.

When we fast, the body has to become metabolically flexible in the sense that we have to start burning alternative fuels for energy. 

When you are taking in calories from a well-rounded diet on a consistent basis to meet your energy needs, your body can readily use carbohydrates and fats to create energy and maintain proper blood glucose levels. 

Certain cells in the body, such as the brain cells and the cells in the medulla of the kidneys, require glucose (sugar) to survive and cannot use alternative sources of energy. 

This glucose can be easily obtained by breaking down dietary carbohydrates or stored glycogen in your muscles and liver. However, if you are on a low-carbohydrate diet or are fasting, your glycogen stores will become depleted, leaving no ready access to glucose. 

In these situations, the liver can create glucose, in a process termed gluconeogenesis, through other substrates. However, this process is energy intensive. 

Practicing shorter fasting protocols can help your body become more efficient at this gluconeogenesis, as well as burning ketones for energy, which is the other metabolic “consequence“ of prolonged fasting. 

Ketosis is associated with many physical benefits, but it can be a shock to the body if you are suddenly having to function largely on ketones for energy when you are accustomed to carbohydrates.

Intermittent fasting is written on a clipboard, an empty plate, a clock, and utensils.

Even if you decide that you do not want to try any sort of shorter fasting protocols to practice for your full 2 day water fasting diet, it is still a good idea to be deliberate in your food choices in the several days leading up to your water fast. 

Focus on eating nourishing, easily digestible foods such as fresh vegetables and fruits, lean proteins, eggs, soups, and fermented foods. 

Avoid alcohol, excessive caffeine, and processed foods high in sugar, salt, and industrial oils. It is also usually helpful to avoid particularly fatty meats and rich, heavy foods, as these can slow digestion and ultimately are probably not supportive of the health and weight loss goals you are striving for by taking on a 48 hour water fast in the first place.

Mentally preparing for a 2 day water fast is highly individualized and depends on your experience with fasting, your comfort level being hungry, and methods that work well for you to help you through difficult situations— your best “self-care tool kit, “ if you will.

It is a good idea to preemptively brainstorm a few strategies that tend to help you through uncomfortable physical and emotional sensations and be prepared to rely on them when things get tough.

Examples include journaling, mindfulness meditation, walking, arts and crafts, Reiki, prayer, singing, or relaxing by watching your favorite TV shows.

Ultimately there’s no way around it: fasting for 48 hours is likely going to be physically and emotionally difficult, and you will experience hunger pangs, dips in energy, and moods that you might not be accustomed to.

However, if you are motivated by the potential benefit of a 2 day water fast, these discomforts might be worth it and are all part of the journey; furthermore, it is partially the very challenge of overcoming the discomfort that drives many people to do prolonged fasting.

The one thing to be mindful of is that if you start to experience adverse symptoms or concerning physical sensations, it is important to let go of your ego and your motivational drive to accomplish what you have set out to achieve and seek medical support or resume eating as soon as possible.

Electrolyte powder being poured into a glass.

How to Do a 2 Day Water Fast

Once the 2 day water fast begins, all you have to do is drink plain water, or water with unsweetened electrolyte powders, for a full 48 hours.

Aim to drink a minimum of 1-2 liters of water per day, and more if you have a larger body, sweat a lot, or live in a hot climate.

Electrolyte tablets will help prevent electrolyte imbalances, or hyponatremia, a potentially fatal condition in which sodium concentration in your body becomes too depleted.

A 48 hour water fast is a challenging but potentially doable approach to boosting health and reducing body fat. However, it is advisable to speak with your healthcare team before embarking on a 2 day water fast to make sure it’s the best choice for you.

To start out with a 24-hour water fast first, check out our guide to 24-hour water fasting here.

A clock with utensils as hands.
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Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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