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How Often Should You Fast? A Guide To Fasting Frequency

Once you start an intermittent fasting diet or try your first 24-hour water fast, the next logical questions are: “How often should I do intermittent fasting, or how often should I be fasting?”

Knowing the best fasting frequency will help you achieve your health and weight loss goals by fasting.

So, how often should you be intermittent fasting? How often should you fast for 24 hours? How often should you do a 48 hour fast? What factors affect how often you should fast?

In this guide, we will discuss factors that affect the question, how often should you fast, guidelines and recommendations for how often you can safely practice intermittent fasting, and other recommendations for optimal fasting frequency.

We will look at: 

  • How Often Should You Fast? 3 Factors to Consider
  • How Often Should You Fast?

Let’s get started!

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How Often Should You Fast? 3 Factors to Consider

Ultimately, there isn’t a single best answer as to how often you should fast because there are numerous factors that affect fasting routines, both in terms of how long you should be fasting and how often you should be fasting.

It is very important to consider all of the factors that affect optimal intermittent fasting schedules and frequency, as well as the best fasting protocols and frequencies for longer fasting, such as a 24-hour fast or a 48-hour fast.

Here are some factors to consider when deciding how often you should fast:

#1: Your Fasting Duration 

Above all, the primary factor to consider when trying to answer the question: “How often should you fast?” is how long you are fasting for.

In other words, the best fasting frequency will depend on how long you are fasting when you fast.

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There will be different answers to the following questions:

  • How often should you intermittent fast?
  • How often should you do a 24 hour fast? How often should you do a 48 hour fast? 
  • How often should you do alternate day fasting? 
  • How often should you do a 5 day fast?

As can likely be assumed, the longer you are fasting at a given time, the less frequently you can and should be fasting.

While most medical and nutrition experts say that it is safe to follow an intermittent fasting diet every day, once you get up to 24 hour fasting or more, you will need to fast much less often in order to give your body a break.

With prolonged water fasting, you are not taking in calories, so there is only so often you can be fasting 48 hours or 72 hours while still meeting you are nutrient needs for health.

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#2: Your Weight Loss and Health Goals

People practice intermittent fasting and extended water fasting for different reasons, ranging from weight loss to improved insulin regulation, decreased inflammation, and accelerated autophagy.

Your goal with fasting will not only affect how often you should fast to reach your goals but also how long you should be fasting, which then, in turn, feeds back into how often you should be fasting.

Fasting for weight loss can be achieved with a general time-restricted intermittent fasting diet.

Some other benefits of fasting, such as autophagy, are seen in longer fasting protocols and may take up to 24 to 36 hours to even set in, which then means that you will need to be fasting longer for health.

Another consideration with how often you should fast for weight loss is how much weight you have to lose and your other diet and lifestyle choices that you are implementing to lose weight.

For example, if you are trying to do a 24 hour fast to lose weight but also do intermittent fasting during the week, follow a calorie-restricted diet, and/or exercise alot, you will not need to fast 24 hours as often to achieve your weight loss goals relative to if you are only doing a periodic 24 hour fast to lose the same amount of weight.

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#3: Your Health Status

If you have any chronic or acute medical conditions, you will likely be encouraged to fast less frequently unless you have obesity, diabetes, or a medical condition such as epilepsy in which your healthcare team specifically wants you to practice fasting for weight loss or health.

How Often Should You Fast?

Given the aforementioned factors and the disclaimer about the safety of prolonged fasting, here are some recommendations and guidelines as to how often you can fast:

How Often Should You Intermittent Fast?

As long as you are in good health, most health experts say that you can practice intermittent fasting every day long-term without consequences as long as you meet your nutritional needs and feel OK with your intermittent fasting diet schedule.

This refers to a time-restricted intermittent fasting diet wherein you limit your eating window to a certain number of hours per day and prolong the overnight fast accordingly.

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The most common intermittent fasting diet schedule is the 18/6 intermittent fasting diet.

This is where you fast for 16 hours overnight and into the next morning, and then you have an 8-hour window of time in which you will consume all of your caloric food and beverages for the day.

For example, you might begin your overnight fast at 6 PM by finishing your dinner every night at 6 PM, and then not have your first meal of the day until 10 AM the following day.

Perhaps aside from the one meal a day (OMAD) diet, which can essentially be considered a 23/1 intermittent fasting diet, any intermittent fasting schedule can be practiced every day, and you don’t have to take a break unless you would like to incorporate off days when you feel like it.

Because the OMAD intermittent fasting diet is pretty taxing on the body because you are going nearly 24 hours a day every day without eating, it is a good idea to take at least one day a week wherein you loosen up the fasting window.

You can do this by doing 20/4 intermittent fasting or taking a total break from fasting once or twice a month.

A January calendar.

How Often Can You Fast for 24 Hours?

A 1 day fast, or fasting for a full day, is generally a safe approach to weight loss and health once a week.

People who have more experience fasting and are practicing alternate-day fasting may be able to do a 24-hour fast several times per week.

However, if this is your preferred weight loss diet approach, you should speak with your doctor beforehand to make sure that multiple 24-hour fasts per week are going to be safe and ideal for you.

How Often Can You Fast for 48 Hours?

Most health experts are in agreement that a 48-hour fast can be safely performed up to twice a month, but these 2-day water fasts should be separated by at least one full week of regular eating or some type of moderate intermittent fasting diet schedule.

How Often Can You Fast for 3 Days? 

A 72-hour water fast is an increasingly popular fasting duration, but it is quite physically and mentally challenging.

You should be working with your doctor even if you are in good health if you want to do a 3-day water fast.

This type of fasting routine for weight loss can be potentially performed once every month or two, depending on the aforementioned factors.

A person grabbing for a glass of water.

How Often Can You Fast for 5 Days? 

Fasting for 5 days is not advisable for most people. 

It can lead to acute consequences of prolonged fasting, such as dangerous electrolyte imbalances.

That said, if you are working with an experienced healthcare provider who believes that it is safe for you to do a 5 day water fast, you may be able to fast for five days once a quarter (once every three months).

How Often Can You Fast for a Week?

A 7 day water fast is an extreme fasting protocol that should only ever be taken on while working with a doctor throughout the process.

This type of fasting duration should not be attempted more than twice a year.

Overall, while it is generally safe to stick with your intermittent fasting diet every day, the longer that you fast at a time, the less frequently you should be fasting.

Above all, it is best to speak with a knowledgeable nutritionist or healthcare provider who can make individualized recommendations for the ideal fasting duration and frequency based on your health status, weight loss, and health goals.

For more details on intermittent fasting schedule, click here.

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Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and 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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