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Uncategorized » Fasting For 3 Days: Will It Get Your Metabolism Cranking At Full Speed?

Fasting For 3 Days: Will It Get Your Metabolism Cranking At Full Speed?

fasting for 3 days results

What is a Short-Term Fasting?

Have you ever considered fasting for 3 days as a means to better your health or lose weight? Fasting has been done for years by many people for multiple reasons but does it really work, or is it another fad diet? What are the benefits of fasting for 3 days? Will water fasting for 3 days help you lose weight? What are the fasting for 3 days results? Let’s get into the specifics!

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Why Do People Fast?

Fasting is nothing new. It has been around for hundreds of years, even before it became popular for fitness and health reasons. Some of the reasons why people fast include:

  1. For religious or spiritual reasons.
  2. As a way to lose weight.
  3. As a form of a detox plan/diet. Popular detox diets include juice or smoothie diet i.e, the celery juice diet, liver cleanse, the lemon water detox, and colon cleanse (3).
  4. For its perceived health benefits.
  5. While preparing for a medical procedure.

What Is Water Fasting for 3 Days?

This is the practice whereby you do not eat or drink anything for three days. A water fast usually lasts for 24 hours to 72 hours; however, in some cases, water fasting can last up to 30 to 40 days. While a 3-day water fast  is relatively safe, longer fasts must be done under close medical supervision (27).

fasting for 3 days results

What Is the Difference Between Intermittent Fasting and Fasting for 3 Days?

Intermittent fasting is the eating practice that revolves around periods of fasting and eating. Under intermittent fasting (IF), people go through extended periods of fasting, and they have a few short hours (aka the feeding window) where they can eat (19). The most popular forms of IF include (24):

  • Fasting for 16 hours with an 8-hour eating window. This one ranks first on the list of the most popular IF methods.
  • Fasting for 12 hours with a 12-hour feeding window.
  • The 5:2 diet. This is slightly different from all the other IF eating patterns. You consume food normally for 5 days a week and reduce your caloric intake to 600 calories (men) or 500 calories (women) for two days a week.
  • The 24 hours fast, aka the eat-stop-eat diet, which means fasting completely for 1 or 2 days a week.

On the other hand, a fasting for 3 days diet means that you do not eat anything for three days and not just a couple of hours.

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fasting diet for 3 days

Fasting for 3 Days: Top Tips on How to Do It Safely

Water fasting can be brutal for anyone who has never done it before. Here are some things that you can do to make the process easier for you:

1. Start small

If you have never fasted before, do not jump straight into a 3-day fast. Try intermittent fasting and see how you feel about it. After getting used to going without food for a few hours a day, switch to an alternate day fasting (5:2 diet), and finally a 24-hour fast. These practices will help you prepare you for water fasting for 3 days.

2. Try not to exercise

The subject of working out while fasted is one that always brings up a very heated debate. Some suggest that if you choose to work out while fasted you should only do cardio but not weight lifting (28), while others suggest that this practice could lead to loss of muscle mass and a slower metabolism (17). We suggest that you skip your workouts during this time. Fasting for 3 days means no food, which means that your body does not have enough energy to function properly. Stick to light exercise, such as house chores and walking.

3. Do not attempt water fasting for 3 days if you are unwell

This is pretty much self-explanatory. Under no circumstance should you risk your health for a water fast. Wait until your health has been cleared by a doctor to attempt this.

fasting for 3 days results

4. Consume high-energy foods before fasting for 3 days

They may help keep your energy levels up, especially on the first day. Some of these foods include bananas, fatty fish, brown rice, eggs, goji berries, quinoa, oatmeal, lentils, avocados, and more (2).

5. Timing is everything

Since this diet can make you feel very weak and tired, it is better if you chose to do it on days that are not as busy or demanding. Try the fasting diet for 3 days on Friday, Saturday, and Sunday, instead of during or at the beginning of the week.

6. Drink a lot of water

This keeps you from getting dehydrated.

7. If you feel unwell, stop fasting.

benefits of fasting for 3 days

What to Eat Before Fasting for 3 Days?

There are no specific rules that state what to eat before fasting for 3 days. However, it is advisable for you to eat foods that are healthy and well-balanced. A balanced diet is one that supplies your body with the nutrients that it needs to work effectively.

A healthy diet is one that (14):

  1. Includes lean meats, poultry, fish, beans, eggs, and nuts.
  2. Is low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars.
  3. Emphasizes fruits, vegetables, whole grains, and fat-free or low-fat milk and milk products.
  4. Stays within your daily recommended caloric intake.

Some people also suggest that you should slowly and steadily reduce your caloric intake for about a week or two before the start date of your 3-day water fast. This helps your stomach and body get ready for not having enough energy.

What Can You Eat While Water Fasting for 3 Days?

This diet is very true to its name. While fasting for 3 days, you cannot consume any food and coffee, tea, alcohol, bone broth, and zero-calorie sports drinks are also not allowed (27). You should try to drink 2 to 3 liters (or more) of water a day for the duration.

fasting for 3 days

What to Eat After Fasting for 3 Days?

It is quite tempting to attempt breaking a water fast by eating a huge meal; however, this is not recommended. It is advisable to break your fasting diet for 3 days by having some fruit, a smoothie, or a small meal. Consuming a large meal or huge amounts of food may lead to stomach ache, discomfort, and nausea.

In some rare cases, consuming large amounts of food may lead to refeeding syndrome. Refeeding is the process of reintroducing food after a period of malnourishment or starvation. On the other hand, refeeding syndrome (which occurs during refeeding) is a potentially fatal condition caused by fatal shifts in fluids and electrolytes in malnutrition patients.

These shifts result from hormonal and metabolic changes and may cause serious clinical complications (23). People who are at a high risk of refeeding syndrome include:

  1. Any patient with negligible food intake for more than five days.
  2. Patients who are malnourished due to dysphagia, anorexia nervosa, depression, or alcoholism.
  3. Anyone with reduced absorption of nutrition due to inflammatory bowel disease or coeliac disease.
  4. Oncology/cancer and post-surgery patients.
  5. Patients with dysphagia.
  6. Patients with uncontrolled diabetes mellitus.
heart problems

Who Should NOT Try a Fasting Diet for 3 Days?

While fasting for 3 days is relatively safe for most people, it can be quite dangerous for some people. These exceptions include (9):

  • Patients with diabetes, as it can lead to dangerous dips and spikes in blood sugar.
  • Pregnant women, new moms, or breastfeeding women.
  • Anyone who is ill, under medication, or suffers from uncontrollable migraines.
  • Older adults, children, or teenagers.
  • People with heart problems.
  • People with eating disorders. Fasting has been linked to an increased risk of binge eating and bulimic pathology (11). The risk of triggering such disorders gets worse with anyone with an existing eating disorder.

Are There Any Benefits of Fasting for 3 Days?

Yes, there may be. However, it should be noted that most of the research available on these benefits of water fasting has been done on animals and not human beings. These benefits of a fasting diet for 3 days include:

  • May cause autophagy

A review posted in 2018 suggested that both fasting and calorie restriction may promote autophagy (25).

The term ‘autophagy’ derives from the Ancient Greek for ‘self-eating.’. The human body has about 30 trillion cells (15), and overtime, waste and damaged material can build up in the cells, thus damaging them. Autophagy is the body’s way of cleaning out damaged cells in order to regenerate newer, healthier cells (5).

This process may help stall the development of cancer cells and may help protect liver cells from drug- and alcohol-induced liver injury. Autophagy may also prevent the progression of several liver conditions such as Wilson’s disease, acute liver injury, nonalcoholic fatty liver disease, and chronic alcohol-related liver disease.

In 2015, research also showed that this process controls inflammation, and thus it may improve the outlook for people with infectious and neurodegenerative diseases (26). It should also be noted that excessive autophagy may kill cells in the heart, which may lead to heart problems.

weight loss
  • May lead to weight loss

Some people who try the fasting diet for 3 days do it as a way to lose weight. While people do lose weight, it is important to note that the weight loss is water weight and not fat loss. Research has shown a positive correlation between increased water consumption and weight loss. The reasons that water may lead to weight loss during fasting for 3 days include (6):

  • It is a natural appetite suppressant, so it will help keep your cravings in check during this time.
  • Increases calories burning while you are at rest.
  • Helps burn off fat from food and drinks, carbohydrates, and stored fat.
  • May improve insulin and leptin sensitivity

Leptin is your body’s satiety hormone. This hormone reduces your appetite and makes you feel full. On the other hand, insulin helps regulate blood sugar levels and excess glucose for energy to be used by the body. A water fasting diet for 3 days may lead to your body becoming more sensitive to these two hormones. Increased sensitivity means that both leptin and insulin work better in their respective functions in the body.

  • May lower the risk of chronic diseases

Some research posted in 2014 revealed that intermittent or periodic fasting in rodents helps to protect them against diabetes, several types of cancer, heart disease, and neurodegeneration. In human beings, this process helps reduce the risk of obesity, hypertension, asthma, and rheumatoid arthritis (12).

good cholesterol
  • May increase the levels of ‘good’ cholesterol and reduce triglycerides

A randomized controlled trial done on 30 healthy individuals revealed that one-day fasting increased high-density lipoprotein (HDL) cholesterol levels and decreased triglycerides and weight. This one-day-water fast also increased the levels of the human growth hormone, hemoglobin, and red blood cell count (22).

  • May help lower blood pressure

Clinically supervised water fasts lasting up to 2 weeks have been linked to lower blood pressure (4). This has been further associated with the fact that you are drinking more water and not consuming salt. However, please note that fasting for 3 days is not likely to help lower blood pressure. This is only possible on longer medically supervised fasts.

  • Fasting and cancer

Prolonged fasting may increase cancer treatment efficacy, prevent resistance acquisition and reduce the side effects of chemotherapy (10).

What Are the Side Effects of Fasting for 3 Days?

Despite the above-mentioned benefits of fasting for 3 days, this diet has some dangers and risks that anyone considering trying it should be aware of:

  • Malnutrition

This is also known as nutritional deficiencies. Malnutrition occurs when your body does not absorb nutrients or get enough nutrients from food for it to function properly. Some signs of malnutrition include unexplained fatigue, dry and brittle hair, damaged nails, an unusually pale or swollen tongue, chronic diarrhea, mood swings, and a lack of appetite (1). These nutrient deficiencies can lead to multiple health problems such as digestion problems, skin disorders, stunted or defective bone growth, and even dementia (20).

side effects of fasting for 3 days
  • It will not lead to fat loss

While some people do this diet for the potential health benefits, many are attracted to the fasting for 3 days diet as a way to lose weight. However, as mentioned above most of the weight loss is water weight and not fat loss. Longer fasts (more than a week to almost a month) could lead to an average of 0.9 kgs weight loss per day in the beginning and about 0.3 kgs by the third week (13). But again, this weight loss is most likely due to loss of water weight and loss of muscle mass.

  • May lead to dehydration

Many of us would assume that water fasting means that you will be hydrated throughout. However, many people tend to forget that 20% to 30% of our daily water intake comes from food (7). Thus if you do not increase the amount of water you drink during the fasting period, you will end up being dehydrated.

  • May lead to dizziness on standing up

This is also known as orthostatic hypotension, and it is the result of an unsafe and sudden fall in blood pressure that occurs when you stand up quickly. Other than dehydration, this condition is caused by anemia, heart conditions, long-term bed rest, blood pressure medications, nervous system disorders, and more (21).

water fasting for 3 days
  • Hyponatremia

Also known as water intoxication, it is a condition that occurs when the level of sodium in the blood is too low. This salt is lost through sweat, and that is why working out is discouraged during this time.

  • Binge-eating disorder

This is a serious eating disorder that causes one to frequently consume unusually large amounts of food and feel unable to stop eating. Binge-eating disorder can affect people who are fasting or have undergone a very-low-calorie diet plan.

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How Much Weight Can You Lose Fasting for 3 Days?

Depending on how much you weigh, you may lose 0.9 kgs to 1.4 kilograms (16). In another case, a 205-pound lost 4 kilograms on a 5-day water fast (18). Please remember that irrespective of how much weight you lose, it will not be as a result of fat loss but most probably due to loss of water weight, or muscle loss, or both.

What to Expect When Fasting for 3 Days?

Fasting can result in vitamin and mineral deficiencies, muscle breakdown, and diarrhea. Other Side effects of fasting include dizziness, headaches, low blood sugar, muscle aches, weakness, and fatigue. Anyone who does this for longer may experience  anemia, a weakened immune system, liver and kidney problems, and irregular heartbeat.

Do People Have Stomach Pain When Fasting for 3 Days?

Yes, they do. It is suggested that once you start experiencing abdominal pain during a fast, then you should stop immediately. Some other symptoms that signify that you need to quickly put a stop to your fasting diet for 3 days include dizziness, nausea, loss of consciousness, vomiting, chest pain, and diarrhea (8).

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The Bottom Line: Is Fasting for 3 Days Worth It?

No, it is not. Whether you are looking for potential health benefits or as a way to jumpstart your weight loss, water fasting for 3 days is truly not the way to go about it. This is a very unhealthy and potentially fatal way to try living a healthier life.

Instead of trying fasting or 3 days, try a healthy, well-balanced diet with a caloric deficit of 500 to 1000 calories a day. You should also consult your doctor or dietitian before attempting a calorie deficit diet. A caloric deficit diet and working out for 30 minutes a day is a better way to help you lose weight. If you are still insistent on trying this fast, please be sure to do it under direct medical supervision.

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This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. A licensed physician should be consulted for diagnosis and treatment of any medical conditions. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!


  1. 7 Signs of Inadequate Nutrition (2012, webmd.com)
  2. 27 Foods That Can Give You More Energy (2020, healthline.com)
  3. A Caution Against Detoxes: Breaking Down the 4 Most Popular Types (2019, healthline.com)
  4. Alan Goldhamer, dc: Water Fasting—The Clinical Effectiveness of Rebooting Your Body (2014, ncbi.nlm.nih.gov)
  5. Autophagy: Everything you need to know (2020, medicalnewstoday.com)
  6. Can water help you lose weight? (2018, medicalnewstoday.com)
  7. Contribution of Water from Food and Fluids to Total Water Intake: Analysis of a French and UK Population Surveys (2016, ncbi.nlm.nih.gov)
  8. Diarrhea During Fasting and Other Side Effects (2019, healthline.com)
  9. Do Fasting Diets Work? (2020, webmd.com)
  10. Fasting and cancer: molecular mechanisms and clinical application (2018, ncbi.nlm.nih.gov)
  11. Fasting Increases Risk for Onset of Binge Eating and Bulimic Pathology: A 5-Year Prospective Study (2010, ncbi.nlm.nih.gov)
  12. Fasting: Molecular Mechanisms and Clinical Applications (2014, ncbi.nlm.nih.gov)
  13. Fasting: the history, pathophysiology and complications (1982, pubmed.ncbi.nlm.nih.gov)
  14. Healthy Eating for a Healthy Weight (2020, cdc.gov)
  15. How Many Cells Are in the Human Body? Fast Facts (2018, healthline.com)
  16. How Much Weight Can I Lose in 3 Days? (n.d, livestrong.com)
  17. How to Exercise Safely During Intermittent Fasting (2020, healthline.com)
  18. I Used the COVID-19 Pandemic to Try a 5-Day Fast. This Is What I Learned. (n.d, mensjournal.com)
  19. Intermittent Fasting 101 — The Ultimate Beginner’s Guide (2020, healthline.com)
  20. Nutritional Deficiencies (Malnutrition) (2019, healthline.com)
  21. Orthostatic hypotension (postural hypotension) (2020, mayoclinic.org)
  22. Randomized cross-over trial of short-term water-only fasting: metabolic and cardiovascular consequences (2013, pubmed.ncbi.nlm.nih.gov)
  23. Refeeding syndrome: what it is, and how to prevent and treat it (2008, ncbi.nlm.nih.gov)
  24. Seven Ways to do Intermittent Fasting (2020, medicalnewstoday.com)
  25. The effect of fasting or calorie restriction on autophagy induction: A review of the literature (2018, pubmed.ncbi.nlm.nih.gov)
  26. Therapeutic targeting of autophagy in neurodegenerative and infectious diseases (2015, ncbi.nlm.nih.gov)
  27. Water Fasting: Benefits, Dangers, and Protocols (2020, verywellfit.com)
  28. What to Know About Intermittent Fasting and Your Workouts (2019, menshealth.com)
Clare Kamau

Clare Kamau

Clare is an excellent and experienced writer who has a great interest in nutrition, weight loss, and working out. She believes that everyone should take an interest in health and fitness, as not only do they improve your way of life, but they can also have a significant impact on your health.
As a writer, her goal is to educate her readers about the ways they can reprogram themselves to enjoy exercise, as well as break free from bad eating habits. In her articles, Clare tries to give advice which is backed by scientific research and is also easy to follow on a day-to-day basis. She believes that everyone, no matter their age, gender, or fitness level, can always learn something new that can benefit their health.

Kristen Fleming

Kristen Fleming

I am a U.S. educated and trained Registered Dietitian (MS, RD, CNSC) with clinical and international development experience. I have experience conducting systematic reviews and evaluating the scientific literature both as a graduate student and later to inform my own evidence-based practice as an RD. I am currently based in Lusaka, Zambia after my Peace Corps service was cut short due to the COVID-19 pandemic and looking for some meaningful work to do as I figure out next steps. This would be my first freelance project, but I am a diligent worker and quite used to independent and self-motivated work.

Kristen Fleming, MS, RD, CNSC

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