A 3-day water fast, also called a 72 hour fast, is an extreme version of water fasting that involves consuming only water for 72 hours or 3 full days.
Some people who practice water fasting permit non-caloric beverages like green tea, herbal tea, club soda, or very low-calorie beverages such as black coffee.
It is also common to supplement water with unsweetened electrolyte powders, tablets, or capsules during a 3 day water fast, although strict protocols only allow you to lick pure pink Himalayan salt to attain necessary sodium.
Water fasting for three days can sound overwhelming, if not impossible, if you have never done it before. However, proponents of 3 day water fasts attest that with a little preparation and mental grit, it’s not only worth it but not that hard to do once you try.
In this guide, we will discuss the benefits and risks of a 3 day water fast, what to expect while fasting, and if a 3 day water fast is safe.
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Is 3 Day Water Fasting Safe?
A 24 hour water fast, or water fasting for a day or two, is not particularly uncommon, but longer fasts, such as a 72 hour fast, is fairly extreme and should only be done under medical supervision.
Although studies suggest that prolonged fasting can be safe, water fasting for three days is often not recommended nor safe for some people, and there are usually healthier, less severe alternatives for body weight management and potential benefits for your health and well-being.1Finnell, J. S., Saul, B. C., Goldhamer, A. C., & Myers, T. R. (2018). Is fasting safe? A chart review of adverse events during medically supervised, water-only fasting.BMC Complementary and Alternative Medicine,18(1). https://doi.org/10.1186/s12906-018-2136-6
These may include a shorter fast, an intermittent fasting diet, a well-balanced program of diet and workouts, etc.
It’s highly recommended that you speak with a healthcare professional before embarking on a 3 day fast or any fasting period for that matter, and discuss potential safer alternatives to achieve health and wellness.2Wilhelmi 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 Medicine,20(6), 434–443. https://doi.org/10.1159/000357602
What Are The Potential Risks Of A 3 day Water Fast?
Three days of fasting may result in adverse health and metabolic changes 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.3Ogłodek, E., & Pilis, Prof., W. (2021). Is Water-Only Fasting Safe?Global Advances in Health and Medicine,10, 216495612110311. https://doi.org/10.1177/21649561211031178
Additionally, a 72 hour fast can lead to symptoms such as headaches, nausea, vomiting, constipation, the inability to regulate body temperature, muscle loss, lightheadedness, shakiness, poor healing, blurry vision, difficulty sleeping, mood instability, and adverse nutritional deficiencies.
How To Do A 3 Day Water Fast
If you’ve never tried water fasting before and this is your first time, you’re probably wondering, “How do you do a 3 day water fast?”
This question seems simple enough, but it can actually be trying to pinpoint the answer to two distinct questions:
- How do you do a 3 day water fast from a practical perspective? (i.e., what does water fasting entail, what can you eat, what do you have to do to prepare, etc.); and
- How do you fast for 72 hours from a mental/hunger/discipline standpoint?
Let’s address both of these valid questions.
After you get the go-ahead from your healthcare provider, the next steps are to physically prepare your body and mentally and emotionally prepare your mind to fast for 72 hours.
To physically prepare yourself for a 3 day water fast, it is advisable that you practice with shorter fasting intervals before you take on a full 72 hour fast.
Although this isn’t required, it can help your body get used to the physical sensations of not receiving any type of energy intake for an extended period of time.
For example, you might try a one day fast one week before your 72 hour water fast.
Or, you might try several days of 18/6 intermittent fasting (extending your overnight fast for a full 18 hours and then only allowing the consumption of food during a 6-hour window during the day) or a 20/4 intermittent fasting diet for a week.
If your body is not accustomed to any type of fasting or intermittent caloric restriction, it can be quite jarring to suddenly have a complete absence of calories coming in.
Engaging in “mini” fasts will improve your ability to burn fat and use ketones for energy (ketosis), such as on the keto diet (which will occur after prolonged fasting), making your longer water fast more comfortable.
Whether or not you decide to try shorter fasts to prepare your body, it’s a good idea to be deliberate in your food and beverage choices in the 48 to 72 hours before you begin your water fast.
Eliminate alcohol, soda, excessive caffeine, and processed foods high in sugar, salt, hydrogenated oils, and artificial sweeteners, as these can trigger appetite.
Instead, focus on eating nourishing, unprocessed foods such as vegetables, fruits, complex carbs like whole grains, lean proteins, nuts, seeds, eggs, and fermented foods like yogurt, kefir, sauerkraut, kimchi, and tempeh.
It’s also wise to resist the urge to “stock up“ or overeat with a big meal heading into a 72 hour water fast.
Binging can throw your insulin and blood sugar levels haywire and can also compromise some of the potential weight loss and health benefits of water fasting that you’re ultimately aiming for.
From the very first day of your 3 day water fast begins, you will only drink water (and potentially herbal tea or black coffee if you choose) for a full 72 hours.
You cannot eat any caloric food or beverages, and most people avoid all artificial sweeteners as well.
In terms of the second question about how to mentally do a 3 day water fast, control your cravings, and manage your hunger, it helps to come up with a few strategies you can employ when things get tough.
There’s no “secret” or magic solution that will make fasting for 72 hours feel easy.
However, some people find things like mindfulness meditation, journaling, praying, taking walks, playing golf, listening to audiobooks and podcasts, or doing needle crafts can be a good way to ground themselves when they feel overwhelmed with cravings.
It’s important to state that if you experience any type of concerning symptoms or side effects, you should consult your doctor immediately.
What to Expect With a 3 Day Water Fast
There are a variety of different benefits that can potentially be enjoyed by occasionally doing prolonged fasts or engaging in intermittent fasting with more regularity.
Some of the reported benefits of fasting include the following:
- Supporting weight loss and a reduction in body fat percentage because you are creating a caloric deficit.4Tinsley, G. M., & La Bounty, P. M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans.Nutrition Reviews,73(10), 661–674. https://doi.org/10.1093/nutrit/nuv041
- Reducing oxidative stress and inflammation.5Johnson, 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 Medicine,42(5), 665–674. https://doi.org/10.1016/j.freeradbiomed.2006.12.005
- Reducing insulin levels, which can reduce the risk of insulin resistance while also supporting body fat loss.6Hoddy, 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 Nutrition,35(6), 1380–1385. https://doi.org/10.1016/j.clnu.2016.03.011
- Reducing LDL (“bad”) cholesterol and triglycerides.7Bhutani, 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.Obesity,18(11), 2152–2159. https://doi.org/10.1038/oby.2010.54
- Promoting autophagy and improving cellular health.8Bagherniya, 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 Reviews,47, 183–197. https://doi.org/10.1016/j.arr.2018.08.004
- Reducing the risk of heart failure by as much as 70%.
- Increasing the secretion of human growth hormone (HGH).9Home Page: The American Journal of Clinical Nutrition. (n.d.). Ajcn.nutrition.org. https://ajcn.nutrition.org/
- Reducing the risk of various medical conditions, including cancer and neurodegenerative diseases.
While this list of benefits of fasting is impressive, many of these benefits are achievable with more conservative approaches to fasting as opposed to long-term fasting, such as intermittent fasting diets and periodic 24-hour water fasts.
You might not need to do a full 3 day water fast to achieve the results you are looking for, so it often makes sense to review your options and get professional medical advice from your healthcare provider.
Along with the benefits of a 3 day water fast, there are some downsides as we mentioned above. Not fueling your body can result in feeling tired and make you feel weak, dizzy or even nauseous.
With that said, some people who do occasional 3 day water fasting find that it’s a powerful physical and mental reset that helps them feel much more vibrant, focused, and healthy.
The response to prolonged fasting is quite individual, so work with a healthcare provider and a dietitian you trust, and be open to experimenting to find what works best for you.
It’s important to consider any existing health conditions, such as an eating disorder, when considering a fast.
If you are cleared to try fasting, start with a short-term 24-hour water fast. Check out our guide here.
References
- 1
Finnell, J. S., Saul, B. C., Goldhamer, A. C., & Myers, T. R. (2018). Is fasting safe? A chart review of adverse events during medically supervised, water-only fasting.BMC Complementary and Alternative Medicine,18(1). https://doi.org/10.1186/s12906-018-2136-6
- 2
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 Medicine,20(6), 434–443. https://doi.org/10.1159/000357602
- 3
Ogłodek, E., & Pilis, Prof., W. (2021). Is Water-Only Fasting Safe?Global Advances in Health and Medicine,10, 216495612110311. https://doi.org/10.1177/21649561211031178
- 4
Tinsley, G. M., & La Bounty, P. M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans.Nutrition Reviews,73(10), 661–674. https://doi.org/10.1093/nutrit/nuv041
- 5
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 Medicine,42(5), 665–674. https://doi.org/10.1016/j.freeradbiomed.2006.12.005
- 6
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 Nutrition,35(6), 1380–1385. https://doi.org/10.1016/j.clnu.2016.03.011
- 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.Obesity,18(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 Reviews,47, 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. https://ajcn.nutrition.org/
