Can a water fast help you reset your body?

Can a water fast help you reset your body?

People have used water fasting as a meditative practice. But only recently have we begun to appreciate the ways – backed by science – in which water fasting boosts our health. Researchers have seen water fasting help slow aging, maintain digestion in your gut, and reduce the risk of heart and metabolic disease. When done over a longer period, a water fast becomes a useful option for helping your body continue to work smoothly.


What is intermittent fasting?

During a water fast, you restrict all manner of eating and drinking except for water. While water fasts can be conducted within an intermittent fast (learn more about it here), they are typically done in intervals of 24 to 72 hours in length. More recently, water fasting is increasingly promoted as a viable lifestyle option by health and wellness experts.


What are the benefits of water fasts?

The scientific community has identified a series of health benefits from water fasting.

  • Improved cardiometabolic health: A 2022 study recruited 48 overweight/obese non-diabetic patients, 26 of whom completed the full study [2]. Participants who undertook a water fast of at least 10 days had reduced blood pressure, smaller waist circumference, and lowered low-density lipoprotein (LDL) concentrations. All of which are positive markers of blood cholesterol levels.

  • Reduced hypertension: A 2001 study recruited 68 patients with borderline hypertension and had them fast for 10 days under medical supervision. The study showed that water fasts can alleviate hypertension by reducing blood pressure [3].

  • Enhanced body maintenance: Water fasts - 24 hours after initiation - also induce a process called autophagy [4]. Autophagy is a process where broken-down components in your body’s cells are sent for breakdown and recycling [5]. Broken cellular components can disrupt normal cell function, and toxin accumulation can even cause cells to poison themselves [6];putting you at increased risk of cardiovascular diseases [7], neurodegenerative diseases [8], and cancer [9]. For this reason, inducing autophagy can help maintain your body and even slow down the process of aging.

  • Reduced Type 2 Diabetes risk: A 2020 study of healthy young men showed that those who participated in a 36-hour fast saw reduced insulin production and increased insulin sensitivity [10], both positive markers of a improving metabolism. A 2018 study also showed that restricted feeding with a water fast for 12 weeks induced weight loss [11].


How does a water fast help your gut microbiome?

A growing body of literature shows that water fasts can also provide a host of benefits for your microbiome:

  • Water fasts can be more helpful for your gut than juice fasts. A 2019 study of 16 individuals showed that those who participated in a water fast saw larger changes to their gut microbes than those who did a juice fast [12]. The study also observed that participants with high Fusobacterium levels, a marker of colorectal cancer risk [13], saw lower levels of the microbe after a water fast.

  • Increased abundance of beneficial microbes: A 2018 study conducted on mouse models showed that the mice who underwent alternate-day, water fasting saw increased abundances of bacterial groups associated with probiotics, such as Lactobacillaceae, Bacteroidaceae, and Prevotellaceae [14]. These changes also coincided with fewer cells producing IL-17, an immune system molecule that participates in inflammation, and alongside increased insulin sensitivity and reduced levels of leptin, a hormone produced in response to high-fat levels.

  • Altering the gut-brain axis: A 2020 study showed that diabetic mice with behavioral impairments who underwent a water fast saw improved brain function [15]. These benefits were mediated through the gut-brain axis, a system that links your gut microbiome with your brain.


What should I consider before I begin a water fast?

With all the benefits that come with a water fast, you may feel eager to start one right away. Before jumping in, consider the following: 

  • The length of your water fast: How long you do a water fast will affect your chances of getting side effects. In most cases, adopting a water fast intermittently (read an article about intermittent fasting) will not cause too many issues. On the other hand, fasts longer than 72 hours can reduce kidney function [16]. This can cause side effects such as dehydration, excess uric acid levels that contribute to kidney stone formation, and aberrant ion concentrations in your blood [17].

  • Side effects: Although an intermittent water fast is safe to do on your own, minor side effects can take place [18]. Nausea, back pain, insomnia, dyspepsia, and fatigue (often mild) are the most common side effects. So you should adjust your fasts or speak with your doctor if they make you feel uncomfortable.

  • Some people should not be doing a water fast: If you have a pre-existing medical condition, speak with your doctor before starting a water fast. Here are some other considerations to make:

  • Although Type 1 and 2 diabetics can benefit from a water fast [2], they face a risk of excess glucose in their blood and dehydration.

  • People who are pregnant should not do a water fast in order to maintain the nutrients the growing child needs and to minimize the risk of adverse events.

  • The elderly should also speak with a doctor before starting a water fast. For one, there is a lack of research into the effects of water fasting to the elderly [19]. More importantly, the elderly have distinct needs and comorbidities that may impact their eligibility.


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All the considerations you need to make before and during a water fast may feel overwhelming. The Injoy app gives you a platform to track your symptoms and energy levels so you can adapt and react to any changes in your well being. Take control of your health with Injoy today!


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  2. Scharf E, Zeiler E, Ncube M, et al. The Effects of Prolonged Water-Only Fasting and Refeeding on Markers of Cardiometabolic Risk. Nutrients. 2022;14(6):1183. doi:10.3390/nu14061183

  3. Goldhamer A, Lisle D, Parpia B, Anderson SV, Campbell TC. Medically supervised water-only fasting in the treatment of hypertension. J Manipulative Physiol Ther. 2001;24(5):335-339. doi:10.1067/mmt.2001.115263

  4. Moresi V, Carrer M, Grueter CE, et al. Histone deacetylases 1 and 2 regulate autophagy flux and skeletal muscle homeostasis in mice. Proceedings of the National Academy of Sciences. 2012;109(5):1649-1654. doi:10.1073/pnas.1121159109

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  6. Wong SQ, Kumar AV, Mills J, Lapierre LR. Autophagy in aging and longevity. Hum Genet. 2020;139(3):277-290. doi:10.1007/s00439-019-02031-7

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  8. Nixon RA. The role of autophagy in neurodegenerative disease. Nat Med. 2013;19(8):983-997. doi:10.1038/nm.3232

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  10. Jørgensen SW, Hjort L, Gillberg L, et al. Impact of prolonged fasting on insulin secretion, insulin action, and hepatic versus whole body insulin secretion disposition indices in healthy young males. Am J Physiol Endocrinol Metab. 2021;320(2):E281-E290. doi:10.1152/ajpendo.00433.2020

  11. Gabel K, Hoddy KK, Haggerty N, et al. Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. Nutrition and Healthy Aging. 2018;4(4):345-353. doi:10.3233/NHA-170036

  12. He Y, Yin J, Lei J, et al. Fasting challenges human gut microbiome resilience and reduces Fusobacterium. Medicine in Microecology. 2019;1-2:100003. doi:10.1016/j.medmic.2019.100003

  13. Zhou Z, Chen J, Yao H, Hu H. Fusobacterium and Colorectal Cancer. Frontiers in Oncology. 2018;8. Accessed April 6, 2023.

  14. Cignarella F, Cantoni C, Ghezzi L, et al. Intermittent Fasting Confers Protection in CNS Autoimmunity by Altering the Gut Microbiota. Cell Metabolism. 2018;27(6):1222-1235.e6. doi:10.1016/j.cmet.2018.05.006

  15. Liu Z, Dai X, Zhang H, et al. Gut microbiota mediates intermittent-fasting alleviation of diabetes-induced cognitive impairment. Nat Commun. 2020;11(1):855. doi:10.1038/s41467-020-14676-4

  16. Mojto V, Gvozdjakova A, Kucharska J, Rausova Z, Vancova O, Valuch J. Effects of complete water fasting and regeneration diet on kidney function, oxidative stress and antioxidants. Bratisl Lek Listy. 2018;119(2):107-111. doi:10.4149/BLL_2018_020

  17. Ogłodek E, Pilis, Prof. W. Is Water-Only Fasting Safe? Glob Adv Health Med. 2021;10:21649561211031176. doi:10.1177/21649561211031178

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  19. Gramont B, Killian M, Bernard E, et al. Therapeutic Fasting: Are Patients Aged 65 and Over Ready? Nutrients. 2022;14(10):2001. doi:10.3390/nu14102001

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