Benefits of a 72 Hour Fast: Unlock Cellular Repair, Weight Loss, and Lower Blood Sugar Levels

A lot of people are drawn towards the idea of fasting these days. It has been an integral part of several cultural and spiritual practices for ages and is becoming popular among people wanting to lose weight.

One of the reasons behind the growing popularity of fasting is its benefits (1). A 72 hour prolonged fast is emerging as one of the most effective weight loss diets. It involves drinking nothing but plain water for three days.

As a healthcare provider, I would not advise my readers to begin with this fast straight away. If you are a beginner, a shorter duration would be ideal. Once comfortable, you can gradually increase your fasting hours.

What is a 72-Hour Fast, and Can it Help You Lose Weight?

In a 72-hour fast, you are expected to forgo all food and caloric beverages for three complete days. You can only have plain water during the fast.

Now, to respond to the next part of the question, i.e., whether a 72-hour fast can be effective in your weight loss journey, the answer is yes!

It is not unusual to see people trying different fasting and dieting methods to lose weight. However, some fasting methods, such as the 72-hour fast, have helped many of my clients lose weight.

Since the 72-hour fast is a prolonged fast, I suggest you speak with your healthcare provider before attempting it, especially if you have any pre-existing medical conditions or have never tried fasting before.

Benefits of a 72 Hour Fast

This is how a three-day fast can potentially benefit you:

1. Aid in Weight Loss

So, if you have set a target to lose weight and wish to try a 72-hour fast, here’s how that happens.

Fasting for 24 hours or more pushes your body into ketosis — a metabolic condition in which your body starts burning the reserved glycogen to provide energy to your body for its functioning (2). When your body is in a state of ketosis, it becomes increasingly efficient at burning stored fat for energy, facilitating weight loss. 

Since you are not consuming more calories, you lose weight due to the calorie deficit. An average American consumes around 2,000-2,500 calories in a day. A three-day water fast would mean a deficit of around 6,000-7,500 calories. (3)

2. Reduces Chronic Inflammation and Oxidative Stress

Fasting beyond 24 hours has been associated with a reduction in oxidative stress. High oxidative stress can trigger inflammation in the body, which is often a cause of several chronic diseases. 

Fasting for 72 hours increases antioxidant enzyme activities and reduces LDL cholesterol in your body, thereby reducing oxidative stress and controlling inflammation. (4, 5)

3. Promotes Cellular Repair and Slow Aging

Studies indicate that prolonged fasting induces autophagy. Autophagy is a natural process that recycles damaged cells and discards unwanted matter. It has a therapeutic impact on many metabolic conditions, neurodegenerative diseases, and cancer, among others. It slows aging and improves longevity. (6)

4. Boosts Human Growth Hormone

Obesity is characterized by reduced production of the growth hormone. Studies reveal that fasting boosts human growth hormone (HGH). It aids in weight loss by reducing and redistributing body fat. (7)
 

5. Regulates Blood Sugar

Fasting improves insulin sensitivity and regulates spikes or drops in blood sugar levels (8). Individuals with type 2 diabetes may benefit from fasting as improved insulin sensitivity means lower insulin requirements and normalized glucose levels.

Stages of a 72-Hour Fast

A fast can impact your metabolism, helping you lose weight. Here are the various stages of a 72-hour fast:

1. 0-12 hours: During this period, your body is busy digesting food, which may result in an insulin peak.
2. 12-18 hours: Your body begins to burn fat, and your insulin levels begin to fall.
3. 18 -24 hours: During this stage, your body enters a state of ketosis and may witness a rise in glucagon levels. Glucagon is a peptide hormone secreted by the pancreas. It is also known for its catabolic properties and may raise the glucose and fatty acids in your bloodstream.
4. 24-48 hours: Autophagy begins, and damaged cells start to be repaired and recycled.
5. 48-54 hours: In this phase, you can expect a drop in inflammation and a surge in the Human Growth Hormone.
6. 54-72 hours: The body experiences insulin sensitizing. This stage may also mark the peak of autophagy.

Beyond 72 hours, stem cells may begin to form, creating new immune cells. You might experience lowered oxidative stress, preventing aging and other age-related diseases.

Risks of a 72 Hour Fast

Now that we’ve discussed the benefits of a 72-hour fast, let me explain the possible side effects of this prolonged fasting regime.

If you are practicing a 72-hour fast, you should be careful about the following factors:

Dehydration

Going without water for three days could lead to dehydration. Even though your body is completely dependent on water throughout the fasting hours, it is still deprived of the water from your food.

Drinking water regularly throughout the fast and adding non-caloric electrolyte supplements can replenish your body and help maintain the electrolyte balance.

Nutritional Deficiencies

Although fasting just once for 72 hours may not lead to deficiencies, repeating such fasts frequently may cause nutritional deficiencies. Lack of food for a prolonged period can deprive the body of macro and micronutrients — minerals and vitamins such as potassium, sodium, and chlorine. (9)

Loss of Lean Muscle Mass

Studies indicate that in water fasting, almost two-thirds of the weight loss is lean muscle loss, while one-third is from fat mass. (10)

Other possible side effects of a 72-hour fast include headache, nausea, loss of appetite, blood pressure drop, and hypoglycemia. (11)

Things to Consider in a 72 Hour Fast

If you’ve decided to take up a 72-hour fast, here are a few points to help you plan the regimen better:

• It is better to start with shorter intermittent fasting or shorter water fasts before going for a three-day fast. You should gradually increase the fasting window until you reach the 72-hour mark.
• Start prepping your body for a fast by following a healthy diet. Eliminating refined, processed, and sugary foods can help your body adapt better to a fast.
• Keep non-caloric electrolyte supplements handy to avoid dehydration.
• Break your fast with simple, easily digestible, and light food. Avoid carbohydrate-dense and junk food. Avoid heavy or large meals when breaking a 72-hour fast.

FAQs

How can I prepare for a 72-hour fast?

You can prepare for a 72-hour fast by beginning with a shorter fasting duration. Those new to fasting can begin with the 16:8 intermittent fasting method and work up to a longer fast.

It is recommended to follow a healthy diet and lifestyle before you commence a prolonged fast. Including proteins, minerals, and vitamins in your diet can nourish your body with essential nutrients, supporting your body through the three-day fasting period. Ensure you drink plenty of water to keep your body well-hydrated before and throughout the fast.

How should I break a 72-hour fast?

You can break your 72-hour fast by consuming simple and easily digestible food. Fruits or boiled vegetables are a good choice. Avoid eating heavy or large portions of food when breaking your fast. Ensure you drink plenty of fluids to keep yourself hydrated even after you break your fast. 

Can I drink anything other than water during a three-day fast?

During a 72-hour fast, you can only consume plain water. However, if your body needs it, incorporating non-caloric electrolyte supplements is permissible. 

Electrolytes can aid in replenishing your body during a prolonged fast, although what you consume should have zero calories to avoid breaking your fast. 

Can I exercise during a 72-hour fast?

Yes, you can exercise during your 72-hour fast, provided you engage in light exercises and avoid strenuous or long workouts. Going for a walk and yoga can be rejuvenating. However, it is essential to keep yourself well-hydrated throughout the fast.   

Is it safe to do a 72-hour fast?

Yes, it is safe to do a 72-hour fast, provided you follow the appropriate approach. Make sure you have no medical conditions that could put your health at risk with a prolonged fast. Keep yourself well hydrated through the fast, and consult a medical expert if you experience any uneasiness. 

Concluding Thoughts

With potential benefits such as improved cognitive functions, reduced inflammation, and lowered blood sugar levels, a 3-day fast is effective for weight loss. Embarking on a 72-hour fast can yield the expected outcomes only if executed correctly.

Long fasts initiate processes such as ketosis and autophagy, eliminate dysfunctional cells, and generate healthier cells. However, such prolonged fasts should not be done frequently as they may result in nutritional deficiencies.

From my experience, I suggest you drink plenty of water throughout your fasting duration and preferably attempt a shorter fast before attempting a three-day fast. Starting with a 24-hour fast and graduating to a 48-hour fast helped me prepare for the 72-hour fast. Towards the end of my 72-hour fast, I did feel the need to include non-caloric electrolyte supplements to ensure electrolyte balance.

References

1. Ding XQ, Maudsley AA, Schweiger U, et al. Effects of a 72 hours fasting on brain metabolism in healthy women studied in vivo with magnetic resonance spectroscopic imaging. J Cereb Blood Flow Metab. 2018;38(3):469-478. doi:10.1177/0271678X17697721
2. Sanvictores, T. (2023, July 24). Physiology, Fasting. StatPearls – NCBI Bookshelf.
3. Strasser, B., Spreitzer, A., & Haber, P. (2007, January 1). Fat Loss Depends on Energy Deficit Only, Independently of the Method for Weight Loss. Annals of Nutrition and Metabolism.
4. Johnson, James B., et al. “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, vol. 42, no. 5, Mar. 2007, pp. 665–674.
5. Hardiany, Novi Silvia, et al. “The Effect of Fasting on Oxidative Stress in the Vital Organs of New Zealand White Rabbit.” Reports of Biochemistry & Molecular Biology, U.S. National Library of Medicine, July 2022.
6. Bagherniya, M., Butler, A. E., Barreto, G. E., & Sahebkar, A. (2018, November 1). The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Ageing Research Reviews.
7. K, H., Veldhuis, J. D., Johnson, M. L., Furlanetto, R. W., Evans, W. S., Alberti, K. G. M. M., & Thorner, M. O. (1988, April 1). Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in men. Journal of Clinical Investigation.
8. Warner, S.O. et al. (no date) ‘Short-term fasting lowers glucagon levels under euglycemic and hypoglycemic conditions in healthy humans’, JCI Insight, 8(12), p. e169789.
9. Dai, Z., Zhang, H., Wu, F., Chen, Y., Yang, C., Wang, H., Sui, X., Guo, Y., Xin, B., Guo, Z., Xiong, J., Wu, B., & Li, Y. (2022, September 18). Effects of 10-Day Complete Fasting on Physiological Homeostasis, Nutrition and Health Markers in Male Adults. 
10. Ezpeleta, M., Cienfuegos, S., Lin, S., Pavlou, V., Gabel, K., & Varady, K. A. (2023, June 27). Efficacy and safety of prolonged water fasting: a narrative review of human trials. Nutrition Reviews.
11. Longo, V.D. et al. (2021) ‘Intermittent and periodic fasting, longevity and disease’, Nature Aging, 1(1), pp. 47–59. Available at: https://doi.org/10.1038/s43587-020-00013-3.

---