Here Are The Benefits Of A 72 Hour Fast

Everything you need to know!

When you first start water fasting, you may begin with an intermittent fasting diet and then work up to a full 24-hour water fasting protocol.

After that, if your body seems to do well with fasting and you experience tangible benefits of fasting with limited side effects or difficulties, you may progress up to a 48 or 72 hour fast.

But, why would you want to do a 72 hour fast? A 72 hour fast can potentially help with your weight loss goals and reduce the risk of certain medical conditions and diseases.

In this article, we will discuss how to do a 72 hour fast, the benefits of a 72 hour fast, possible weight loss results, and tips for 72 hour fasting.

A glass of water.

What Is a 72 Hour Fast? 

Before we go into the specific health benefits of fasting, or discuss potential 72 hour fast weight loss results or potential to burn fat, let’s cover the basics of what a 72 hour fast entails.

A 72 hour fast, also sometimes called a 72 hour water fast, involves abstaining from all food and caloric beverages for a full 72 hours (3 days).

Intermittent fasting diets can be thought of as a mini water fast, and some people then take on longer fasts once a week or once a month, such as a 24-hour water fast, 36-hour water fast, or even multi-day water fast eventually.

As a disclaimer, it’s crucial to establish that water fasting for an extended period of time may not be safe or advisable for certain individuals. It is important to speak with a healthcare professional before attempting a prolonged water fast.1Wilhelmi de Toledo, F., Buchinger, A., Burggrabe, H., Hölz, G., Kuhn, C., Lischka, E., Lischka, N., Lützner, H., May, W., Ritzmann-Widderich, M., Stange, R., Wessel, A., Boschmann, M., Peper, E., & Michalsen, A. (2013). Fasting Therapy – an Expert Panel Update of the 2002 Consensus Guidelines. Forschende Komplementärmedizin / Research in Complementary Medicine20(6), 434–443. https://doi.org/10.1159/000357602

A person meeting with their doctor.

What Are The Potential Side Effects Of Fasting?

Fasting for 72 hours may result in adverse health and metabolic changes2Ogłodek, E., & Pilis, Prof., W. (2021). Is Water-Only Fasting Safe? Global Advances in Health and Medicine10, 216495612110311. https://doi.org/10.1177/21649561211031178 such as dehydration, a loss of lean muscle mass, hyperuricemia, hyponatremia, protein-sparing, sodium and potassium-sparing, decreased serum calcium and magnesium levels, and acidic urine.

It is also helpful to work up to extended water fasting protocols with shorter water fasts. You might begin with an intermittent fasting diet schedule that has you reduce your eating window to eight hours. 

Then, you can gradually increase the duration of the fasting window until you are up to a full 24-hour water fast once a week.

You should not jump into a water fasting challenge longer than 24 hours if you have not tried fasting before or are not working under medical supervision.

Is 72 Hour Water Fasting Good for Weight Loss?

Most people who are not doing a 72 hour water fast for spiritual reasons are primarily interested in this prolonged fasting period for weight loss benefits.

If your healthcare provider determines that it is safe for you to fast for 72 hours, it is certainly possible to lose weight with periodic 3 day fasting.

Depending on your body size and activity level (which together determine your daily caloric needs) and whether you engage in compensatory overeating after fasting 72 hours, you can definitely experience fat loss fasting 72 hours every couple of weeks. 

A person stepping on a scale.

The standard daily recommendations for weight maintenance for average adults set forth in the 2020-2025 Dietary Guidelines for Americans are that adult women should consume 1,600 to 2,400 calories per day, and men should eat 2,000 to 3,000 calories per day.3United States Department of Agriculture. (2020). Dietary Guidelines for Americans 2020 -2025 . USDA. https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf

So, let’s say the average adult needs 2,300 calories per day to maintain their body weight, given their activity level and BMR.

Water fasting for three days would thus put you in about a 7,000-calorie deficit.

Because a caloric deficit of 3,500 calories results in one pound of fat loss, you would experience about 2 pounds of true fat burning loss for every 3-day water fasting protocol you completed.

While a caloric deficit is necessary to lose weight, a prolonged and significant caloric deficit can affect your metabolic health by reducing your metabolic rate through a process known as adaptive thermogenesis.4Martínez-Gómez, M. G., & Roberts, B. M. (2021). Metabolic Adaptations to Weight Loss. Journal of Strength and Conditioning ResearchPublish Ahead of Print. https://doi.org/10.1519/jsc.0000000000003991

‌Over time, this can result in a weight loss plateau and eventual weight gain because your metabolic rate has dropped so significantly that you need very few calories to sustain your daily activities. 

Therefore, because water fasting is metabolically taxing for your body and you don’t want to compromise your metabolic rate, your body needs some time to recover after fasting 3 days, and you should not do a full 72 hour water fast more than twice a month. 

Even with this limited frequency, water fasting 72 hours twice a month could result in about 4 pounds of fat loss per month without any other changes to your diet or exercise routine, and studies have found that fasting can improve body composition.5Tinsley, G. M., & La Bounty, P. M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews73(10), 661–674. https://doi.org/10.1093/nutrit/nuv041

A person drinking a bottle of water.

Additional Benefits Of A 72 Hour Fast

Aside from weight loss, additional 72 hour fast benefits include:

How to Do a 72 Hour Water Fast

After getting medical clearance from your doctor, you will plan when you want to do your 72 hour water fast and will get any supplies necessary for your water fasting protocol.

In terms of “supplies,” this entails electrolyte tablets or unsweetened electrolyte powders as supplements for hydration. It is highly recommended to take in electrolytes during a 3 day water fast in order to prevent dangerous electrolyte imbalances. 

Doing a 72 hour water fast is as simple as it sounds: you abstain from eating anything and drinking any caloric beverages for a full 72 hours.

You can drink non-caloric beverages, including water, seltzer, club soda, herbal tea, unsweetened caffeinated tea, and black coffee.

As mentioned, you should add electrolytes to your water when you are doing 72 hour water fasting or any extended fasting protocols.

A cup of herbal tea.

Is a 72 Hour Fast Worth It?

It’s undeniable that doing a 72 hour fast is physically, emotionally, mentally, and potentially even spiritually draining. 

In general, before trying a 72 hour water fast, it’s important to compare the benefits of fasting 72 vs 24 or even 48 hours.

For many people, a shorter fasting protocol can still provide many of the same benefits of fasting 72 hours but in a much more manageable—and likely safer—way.

For some people, extending the duration of a water fast by doing a 72 vs 48 hour fast gets exponentially harder in that the additional 24 hours. It can feel like it stretches for days effecting your well-being and wellness in general.

For other people, once you are doing prolonged fasting, your body and mind adjust to the discomfort of hunger and the lack of taking in calories, and it actually doesn’t feel appreciably more difficult to do a 3 vs 2 day fasting protocol.

A runner on a track bend over tired.

It’s not entirely clear why there are discrepancies in how our bodies respond to extended fasting in terms of appetite, but some people may either experience less of an increase in ghrelin (the appetite hormone) or may be better at disassociating from the physiological and psychological discomfort of being hungry and not being able to eat.

Water fasting 72 hours can cause general low energy, irritability, hunger, hormonal disruptions, difficulty sleeping, etc. 

Moreover, abstaining from all caloric intake-–especially carbohydrates—while fasting for 3 days makes it difficult (if not unsafe) to perform vigorous exercise. 

This can also compromise 72 hour fasting weight loss results because if you are less active, both through structured workouts as well as daily physical activity, you will burn fewer calories.

If your caloric expenditure drops, the caloric expenditure you create by fasting 72 hours will also decrease, so fat loss results will be reduced.

A person sitting on a bench at the gym, tired.

Furthermore, if you are an endurance athlete, such as a runner, cyclist, or triathlete, or you want to perform high-intensity workouts such as heavy weightlifting, plyometrics, or HIIT workouts, your muscles likely will not have the fuel (glycogen) necessary to support the vigorous nature of your workouts due to lack of food intake. 

This will compromise your athletic performance. For this reason, water fasting 72 hours is not recommended for athletes hoping to support exercise performance or who are training for a competition.

Overall, unless your healthcare team is recommending fasting 72 hours, you may be best served by taking a more moderate approach to fasting with an intermittent fasting diet, or shorter, more frequent water fasting, such as water fasting 24 hours once a week.

Prolonged fasting may not be appropriate for people with a history of eating disorders, or women who are pregnant or breastfeeding.11Darmaun, D. (2021). Maternal intermittent fasting during pregnancy: a translational research challenge for an important clinical scenario. Clinical Science135(17), 2099–2102. https://doi.org/10.1042/cs20210578

For a look into more manageable intermittent fasting, check out this next guide:

References

  • 1
    Wilhelmi de Toledo, F., Buchinger, A., Burggrabe, H., Hölz, G., Kuhn, C., Lischka, E., Lischka, N., Lützner, H., May, W., Ritzmann-Widderich, M., Stange, R., Wessel, A., Boschmann, M., Peper, E., & Michalsen, A. (2013). Fasting Therapy – an Expert Panel Update of the 2002 Consensus Guidelines. Forschende Komplementärmedizin / Research in Complementary Medicine20(6), 434–443. https://doi.org/10.1159/000357602
  • 2
    Ogłodek, E., & Pilis, Prof., W. (2021). Is Water-Only Fasting Safe? Global Advances in Health and Medicine10, 216495612110311. https://doi.org/10.1177/21649561211031178
  • 3
    United States Department of Agriculture. (2020). Dietary Guidelines for Americans 2020 -2025 . USDA. https://www.dietaryguidelines.gov/sites/default/files/2020-12/Dietary_Guidelines_for_Americans_2020-2025.pdf
  • 4
    Martínez-Gómez, M. G., & Roberts, B. M. (2021). Metabolic Adaptations to Weight Loss. Journal of Strength and Conditioning ResearchPublish Ahead of Print. https://doi.org/10.1519/jsc.0000000000003991
  • 5
    Tinsley, G. M., & La Bounty, P. M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews73(10), 661–674. https://doi.org/10.1093/nutrit/nuv041
  • 6
    Johnson, J. B., Summer, W., Cutler, R. G., Martin, B., Hyun, D.-H., Dixit, V. D., Pearson, M., Nassar, M., Tellejohan, R., Maudsley, S., Carlson, O., John, S., Laub, D. R., & Mattson, M. P. (2007). Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Radical Biology and Medicine42(5), 665–674. https://doi.org/10.1016/j.freeradbiomed.2006.12.005
  • 7
    Bhutani, S., Klempel, M. C., Berger, R. A., & Varady, K. A. (2010). Improvements in Coronary Heart Disease Risk Indicators by Alternate-Day Fasting Involve Adipose Tissue Modulations. Obesity18(11), 2152–2159. https://doi.org/10.1038/oby.2010.54
  • 8
    Bagherniya, M., Butler, A. E., Barreto, G. E., & Sahebkar, A. (2018). The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Ageing Research Reviews47, 183–197. https://doi.org/10.1016/j.arr.2018.08.004
  • 9
    Home Page: The American Journal of Clinical Nutrition. (n.d.). Ajcn.nutrition.org.
  • 10
    Hoddy, K. K., Gibbons, C., Kroeger, C. M., Trepanowski, J. F., Barnosky, A., Bhutani, S., Gabel, K., Finlayson, G., & Varady, K. A. (2016). Changes in hunger and fullness in relation to gut peptides before and after 8 weeks of alternate day fasting. Clinical Nutrition35(6), 1380–1385. https://doi.org/10.1016/j.clnu.2016.03.011
  • 11
    Darmaun, D. (2021). Maternal intermittent fasting during pregnancy: a translational research challenge for an important clinical scenario. Clinical Science135(17), 2099–2102. https://doi.org/10.1042/cs20210578
Photo of author
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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