72 Hour Fasting Benefits on the Immune System

Prolonged caloric restriction, such as a 72-hour fast, is a powerful tool for optimizing hormonal balance, supporting immune system functions, and enhancing metabolic health.

However, restricting food intake for three days can be challenging, especially for those new to fasting. 

Discover the impressive health benefits of extended fasting periods and learn how to safely and successfully complete a 72-hour fast. 

What is a 72-hour fast?

A 72-hour fast involves abstaining from food for three consecutive days while allowing water, electrolytes, and non-caloric beverages such as herbal teas and moderate amounts of black coffee.

During extended fasting periods, the body shifts from utilizing sugars as the primary fuel source to burning fat to generate energy, a metabolic state known as ketosis. 

Ketosis occurs when the body begins to burn fat, converting fatty acids into ketone bodies, a group of organic acids that serve as a highly efficient alternative fuel source when glucose is limited. 

This metabolic shift forces the body to tap into stored body fat, promoting both fat loss and an overall reduction in body weight. 

With each fasting hour, the body becomes more efficient at burning fat, making a 72-hour fast an effective strategy for those seeking to lose weight and improve their metabolic health.

In addition to significant weight loss, prolonged fasting has also been linked to improved mental clarity, antiaging effects, cellular rejuvenation, and a lower risk of chronic inflammatory diseases.   

While some individuals prefer to practice prolonged fasting monthly, others opt for a three-day fast every other month or whenever they feel the need for a metabolic reset.

Watch the video below to explore the remarkable immune system benefits of a 72-hour fast. 

5 benefits of a 72-hour fast

Fasting offers various health benefits, especially for individuals seeking to promote a healthy body weight, enhance metabolic functions, and support overall well-being.

Let’s take a look at five benefits of a 72-hour fast. 

1. Supports cardiometabolic health  

One of the most profound advantages of a 72-hour fast is its positive impact on cardiometabolic health. 

Prolonged fasting has been shown to help reduce insulin resistance, which is characterized by cells not responding effectively to insulin signaling. 

Insulin resistance is often linked to excess body weight and a high-carb diet and is a leading cause of metabolic imbalances and heart disease. 

Fasting promotes steady insulin levels, which helps improve insulin sensitivity and may even reverse insulin resistance, which has been linked to a lower risk of metabolic syndrome, obesity, and type 2 diabetes. 

This has been confirmed by research published in JAMA Internal Medicine, suggesting that extended fasting protocols are associated with significant weight loss and improvements in cardiometabolic risk factors, including insulin sensitivity and blood pressure.

2. Improved mental clarity

Many individuals who practice fasting report better cognitive function, enhanced mental clarity, and improved moods.

During fasting periods, the liver releases large amounts of ketones that serve as a highly efficient fuel source for brain cells, promoting cognitive performance and sharper focus. 

In addition, a study published in Medicina found that fasting is associated with an increased release of brain-derived neurotrophic factor (BDNF). This critical protein facilitates neurogenesis and synaptic plasticity, which is vital for learning, memory, and better brain health. 

The benefits of caloric restriction for brain function may also explain why individuals who regularly practice prolonged fasting appear at lower risk of neurodegenerative disorders such as dementia and Alzheimer’s disease. 

3. Enhanced immune defenses

Fasting for prolonged periods is an excellent strategy to support strong immune system functions. 

Evidence published in Aging Cell reports that a 72-hour fast promotes the regeneration and activity of immune cells, including neutrophils and T-regulatory cells. 

These cells play a critical role in regulating immune activity and suppressing overactive immune responses, which can help reduce inflammation and lower the risk of autoimmune diseases. 

By rejuvenating immune cells and enhancing immune defenses, fasting may contribute to better overall health, protect from chronic inflammation, and improve resilience against microbial infections.

4. Stimulates cellular renewal

Extended fasting periods trigger a cellular repair process known as autophagy, which facilitates the removal and recycling of damaged cells and promotes the regeneration of new ones. 

This critical renewal mechanism is vital for maintaining cellular health, as it also removes toxins, waste, and damaged cellular organelles, thereby supporting the body’s ability to heal and repair itself.

Because of the profound benefits of autophagy for cellular function, fasting may be especially important for individuals with neurodegenerative diseases, cardiovascular issues, and metabolic disorders.

5. Anti-aging effects 

Fasting for 72 hours has potential anti-aging effects and may help slow down the aging process at the cellular level. 

It’s believed that the combination of fasting-related autophagy, enhanced immune functions, and improved metabolic health greatly support the body’s rejuvenation capacities, thereby promoting longevity and potentially lowering the risk of age-related diseases. 

A study published in Cell Metabolism investigated the link between prolonged fasting, cellular function, and overall health and concluded, “Fasting has the potential to delay aging and help prevent and treat diseases while minimizing the side effects caused by chronic dietary interventions.”

How to start a 72-hour fast

Fasting for 72 hours requires careful preparation to ensure a successful experience. 

Let’s take a look at three practical tips to get you started. 

1. Gradually extend fasting periods

Fasting for too long too soon is a common mistake people make when attempting an extended fast and it's crucial to slowly transition your body into prolonged fasting. 

One effective way to prepare the body for the significant changes triggered by caloric restriction is to practice intermittent fasting, a mealtime schedule that alternates between fasting periods and time-restricted eating windows. 

This approach can be particularly helpful if you‘re new to fasting, as intermittent fasting allows a gradual adaptation to longer periods without food until you can comfortably complete a three-day fast.

2. Plan nutritious meals before fasting 

In the days leading up to a prolonged fast, focus on consuming minimally processed, nutrient-dense whole foods while reducing carbohydrate intake to prime the metabolism for fat-burning and ketosis. 

Consuming plenty of healthy fats and nutritious foods, such as avocados, grass-fed meats, pasture-raised eggs, and green leafy vegetables, helps provide sustained energy and offers essential nutrients crucial for overall well-being. 

3. Choose the right time 

It's equally important to choose the right time to embark on a prolonged fast to minimize disruptions or challenges, such as busy periods at work or major social events, which can make it harder to sustain a prolonged fast. 

Starting your fast during a quieter period, such as a weekend or vacation, can help you focus on the process without added stress or distractions. 

Tips for a successful prolonged fast

To maximize the health benefits of fasting for 72 hours while minimizing the risk of potential fasting-related side effects, it’s crucial to listen to your body and ensure proper hydration, optimal nutrition, and mindful preparation. 

Here are three tips for a successful fast.

1. Stay hydrated and replenish electrolytes 

In the early stages of ketosis, your body may experience fluid and electrolyte loss due to the metabolic changes triggered by caloric restriction. 

Therefore, drinking plenty of fluids during a 72-hour fast is essential. Staying hydrated helps maintain energy levels and can reduce common fasting side effects, including headaches and fatigue.

“Plain water may not keep you hydrated, as the body requires adequate electrolytes to maintain fluid levels,” explains Dr. Berg. “Sugar-free electrolyte powders are a convenient way to replenish essential minerals without adding calories, ensuring you stay hydrated and support your body’s electrolyte needs while fasting.”

2. Break your fast slowly 

After 72 hours of fasting, it’s essential to break your fast gently. Eating rich and heavy meals after prolonged fasting periods can overwhelm your digestive system, leading to discomfort, bloating, and digestive issues.

Instead, start with easily digestible foods, such as bone broth, soups, or stews, and gradually reintroduce solid meals to give your digestive system time to adjust.

3. Follow Healthy Keto®

Following a nutritious, low-fat diet such as Healthy Keto® is an excellent strategy for achieving prolonged fasting success and maximizing the health benefits of caloric restriction.  

Adapting to a high-fat diet transitions the body into utilizing fat as its primary fuel source, which aligns with the metabolic shifts triggered by extended fasting. 

Consuming a high-fat diet during non-fasting periods can help achieve extended fasting periods and reduce fasting-related hunger and cravings, making a 72-hour fast more manageable and comfortable. 

Prolonged fasting safety and risks

While prolonged fasting has impressive health benefits, it’s also associated with certain risks and may not be suitable for everyone. 

For example, pregnant and breastfeeding women shouldn’t fast for prolonged periods as they have higher caloric needs to support their own health and the growth of their baby.

In addition, those with a history of eating disorders should approach fasting with extreme care, as it may trigger unhealthy eating behaviors.

It’s also important to emphasize that medical supervision is crucial, especially for individuals with impaired thyroid dysfunction, diabetes, or cardiovascular issues. 

If you have underlying health conditions or are taking prescription medication, it’s recommended to discuss prolonged fasting with a healthcare professional to help you manage any potential risks.

Even healthy individuals may develop symptoms such as fatigue, dizziness, or electrolyte imbalances during extended fasts. This highlights the importance of carefully listening to your body and adjusting your fasting schedule should you experience any adverse effects.  

Key takeaways

A 72-hour fast offers profound health benefits, including enhanced cellular repair, improved metabolic health, and better immune defenses. 

While fasting for three days may seem challenging, following a nutritious low-carb diet and practicing intermittent fasting can help prime the body for prolonged periods of caloric restriction and support a successful prolonged fast. 

To minimize potential adverse effects during an extended fast, it’s crucial to stay hydrated, replenish electrolytes, listen to your body, and adjust your fasting schedule if necessary. 

FAQ

1. Is a 72-hour fast healthy?

Yes, if planned carefully, a 72-hour fast can be healthy for many individuals as it offers potential benefits such as improved metabolic health, enhanced cellular repair, improved insulin sensitivity, and significant weight loss.

However, it’s crucial to discuss fasting with a healthcare provider to ensure it aligns with your health goals and to mitigate any potential risks associated with underlying conditions or medications.

2. What benefits do you get after 72 hours of fasting?

Fasting for 72 hours has been linked to enhanced immune system function, better mental clarity, significant weight loss, and improved insulin sensitivity, which plays a crucial role in metabolic balance and lowers the risk of obesity and diabetes. 

3. How much weight can you lose during a 72-hour fast?

How much weight you can lose during a fast depends on your metabolic health and starting weight. While some people lose between 4 and 7 pounds during a 72-hour fast, others report weight loss of up to 10 pounds when abstaining from food for three days. 

4. What are the rules for a 72-hour fast?

The main rules for a 72-hour fast include abstaining from all food for three days, staying hydrated with plenty of water and non-caloric beverages such as herbal tea or black coffee, and replenishing electrolytes with a sugar-free electrolyte powder.

In addition, it’s crucial to listen to your body and adjust your fasting schedule as necessary. It’s also recommended to break your fast with easy-to-digest foods such as bone broth or soup to minimize the risk of gastrointestinal discomfort.  

5. Is it safe to fast for 72 hours?

Yes, fasting for 72 hours is safe for many individuals, especially if approached with careful preparation. 

However, pregnant women and those with a history of eating disorders should avoid fasting. In addition, individuals with underlying medical conditions should discuss prolonged fasting with a healthcare provider to mitigate any potential fasting-related adverse effects.

6. What can I drink during a 72-hour fast?

Staying hydrated is critical during a fast and non-caloric beverages such as plain or mineral water, herbal teas, or moderate amounts of black coffee are excellent options.

In addition, it’s recommended to replenish electrolytes with a sugar-free electrolyte powder to maintain mineral balance and minimize the risk of muscle cramps, fatigue, and dizziness. 

7. What supplements should I take during a 72-hour fast?

To maintain mineral balance during a prolonged fast, it's recommended to use a sugar-free electrolyte powder to replenish essential electrolytes such as sodium, potassium, and magnesium.

Additionally, many individuals incorporate wheatgrass juice powder to support energy production and overall health without breaking the body’s natural fasting state.

Sources

1. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2794819 

2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10819730/

3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8590100/ 

4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3946160/