Diet Tips

Benefits And Dangers Of Water Fasting

Reviewed by Merlin Annie Raj, Registered Dietitian
ISSA Certified Specialist in Fitness & Nutrition
Benefits And Dangers Of Water Fasting Hyderabd040-395603080 October 22, 2019

Fasting is a great way to reset your metabolism (1). Water fasting, in particular, is a great way to detox, lose weight, and reduce blood pressure (2). But there’s a fine line that separates the benefits of water fasting from its dangers.

Read on to know the 7 benefits of water fasting, how to do it, who should avoid it, and the dangers if you push it too far. Swipe up!

What Is Water Fasting?

Water fasting is a type of fasting in which you only drink water. It typically lasts for 24 hours to 72 hours.

Dr. Alan Goldhamer, founder and education director of TrueNorth Health Center, has helped many patients become healthier through his Clinical Fasting program. He says, “Fasting, by definition, is the complete absence of all substances except water in an environment of complete rest.” So, water fasting and fasting are essentially the same (3).


Water fasting is not the same as clinical fasting. Clinical fasting is supervised by doctors and experts. It is of much longer duration and does not come under the scope of this post.

Here’s how a day or two of water fasting can benefit you. Scroll down.

7 Benefits Of Water Fasting

1. Lowers Blood Pressure

Lowers Blood Pressure Pinit


Consuming too much of junk food, which generally contains high amounts of salt, may raise your blood pressure. Water fasting is an effective way to reduce blood pressure (4).

American scientists found that out of 68 people with borderline hypertension, 82% had reduced blood pressure after they underwent clinical water fasting under medical supervision (5).

Another study led by Dr. Goldhamer studied 174 people with hypertension. By the end of the water fasting duration, 90% of the people were successfully able to stop taking medicines for hypertension (6).

2. Helps Protect The Heart

When you fast for a day or two in a week, you consume fewer calories. As a result, you will lose weight. This, in turn, helps reduce the risk of various types of heart diseases.

Scientists have found that intermittent fasting helps reduce waist circumference and lowers LDL cholesterol, tumor necrosis factor, leptin, and insulin-like growth factor levels (7).

3. Helps Lower Oxidative Stress

Helps Lower Oxidative Stress Pinit


Unhealthy lifestyle and bad food habits cause ROS accumulation. ROS or reactive oxygen species affect cell structure, DNA, proteins, and cell functions. Accumulation of too many reactive oxygen species (ROS) increases oxidative stress and inflammation in the body. Water fasting helps reduce oxidative stress by flushing out ROS (8).

4. Promote Autophagy

Autophagy is your cells’ natural process of eliminating the wastes produced via cell degradation or components that are either dysfunctional or not required by the body. It is basically a cleanup process for your body. If your body fails to do that, it increases the levels of toxins, resulting in diseases like cancer.

Fasting once or twice a week helps your body aid autophagy and reduce the risk of toxin build-up in the body (9).

5. Boosts Immunity

Boosts Immunity Pinit


Water fasting also helps boost immunity. Water helps flush out the excess amounts of toxins. Your cells start functioning normally, and as a result, your immune system also starts functioning better.

6. Improves Insulin and Leptin Sensitivity

Insulin and leptin are hormones that help regulate blood glucose levels and hunger respectively. Fasting makes your body more sensitive to insulin, thereby reducing the risk of diabetes and obesity. Leptin is a satiety hormone that signals the brain when to stop eating. Leptin sensitivity can also help prevent you from overeating, thereby preventing weight gain (10), (11).

7. Lowers the Risk of Several Chronic Diseases

Lowers the Risk of Several Chronic Diseases Pinit


Fasting is a great way to keep most chronic diseases at bay. Scientists report that apart from cancer, diabetes, and heart disease, fasting can help prevent chronic inflammation and rheumatoid arthritis, decrease aging signals, and reduce mitochondrial oxidative stress and triglyceride levels (12), (13).

These are the benefits that you can reap if you water fast for one or two days per week. The question is, should everyone fast? No. Find out if you can fast in the next section.

Who Should Water Fast?

You should fast if:

  • your doctor asked you to.
  • you want to boost your immunity.
  • you are overweight.
  • you are on a supervised fasting program.
  • you want to detox.

Who should avoid fasting? Find out next.

Who Should NOT Water Fast?

You should not fast (or fast according to your doctor’s instructions) if:

  • your doctor does NOT recommend fasting for you.
  • you have hypoglycemia.
  • you have diabetes.
  • you are on any medication.
  • you had recent surgery.
  • you are pregnant.
  • you have just given birth.

Let’s now get down to another business – how to fast. If you do not do it correctly, you can harm your body. Scroll down to find out how to fast safely.

How To Fast

Here are a few helpful pointers:

  • If you are new to fasting, try going without food for 4 hours. Have a heavy breakfast at 8 a.m. in the morning and then break your “fast” at 12 in the noon.
  • Increase the fasting duration gradually to 8 hours. Here’s an easy guide to 8-hour fasting.
  • Try the Ramadan fasting. Load up on proteins, dietary fiber, and healthy fats before sunrise. Eat again after sunset.
  • If you can, increase the fasting duration to 24 hours. Do this once or twice a week.
  • DO NOT gobble up food while breaking the fast. Start with a small portion of food.
  • Keep drinking water.
  • On the non-fasting days, eat the right amounts of food.
  • Stop fasting if you start to feel sick.

While water fasting is good for a limited number of days in a week, doing it for a long duration can cause harm. Here’s what can happen.

Dangers Of Water Fasting

Dangers Of Water Fasting Pinit


  • Causes eating disorders.
  • Causes heartburn and GERD and deteriorates kidney function.
  • You might feel sick and nauseated.
  • Hunger can trigger mood fluctuations.
  • May cause brain fog if you push it too far.

Water fasting can be immensely helpful if done correctly. Just don’t get too enthusiastic! Be patient, and the best results are guaranteed. Also, consult your doctor before you decide to go on a water fast that lasts for more than 8 hours. Cheers!


  1. Fasting boosts stem cells’ regenerative capacity” MIT News.
  2. Effects of complete water fasting and regeneration diet on kidney function, oxidative stress and antioxidants.” Bratislavské lekárske listy, US Library of Medicine.
  3. Alan Goldhamer, dc: Water Fasting—The Clinical Effectiveness of Rebooting Your Body” Integrative medicine, US Library of Medicine.
  4. [The effects of three-week fasting diet on blood pressure, lipid profile and glucoregulation in extremely obese patients].” Srpski arhiv za celokupno lekarstvo, US Library of Medicine.
  5. Medically supervised water-only fasting in the treatment of borderline hypertension.” The journal of alternative and complementary medicine : research on paradigm, practice, and policy, US Library of Medicine.
  6. Medically supervised water-only fasting in the treatment of hypertension.” Journal of manipulative and physiological therapeutics, US Library of Medicine.
  7. Improvement in coronary heart disease risk factors during an intermittent fasting/calorie restriction regimen: Relationship to adipokine modulations” Nutrition & metabolism, US Library of Medicine.
  8. Oxidative Stress and Antioxidant Defense” The World Allergy Organization journal, US Library of Medicine.
  9. Autophagy and intermittent fasting: the connection for cancer therapy?” Clinics, US Library of Medicine.
  10. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes.” Cell metabolism, US Library of Medicine.
  11. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review.” Obesity reviews : an official journal of the International Association for the Study of Obesity, US Library of Medicine.
  12. Fasting therapy for treating and preventing disease – current state of evidence.” Forschende Komplementärmedizin = Research in complementary medicine, US Library of Medicine.
  13. Role of Intermittent Fasting on Improving Health and Reducing Diseases” International journal of health sciences, US Library of Medicine.
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Charushila Biswas

Charushila Biswas is a Senior Content Writer and an ISSA Certified Fitness Nutritionist. She is an alumni of VIT University, Vellore and has worked on transgenic wheat as a part of her Masters dissertation from NRCPB (IARI), New Delhi. After completing her Masters, she developed a passion for nutrition and fitness, which are closely related to human psychology. And that prompted her to author a review article in 2015. She has written over 200 articles on Fitness and Nutrition. In her leisure time, Charushila loves to cook and enjoys mobile photography.