Fasting Hacks: 36 vs. 72 Hours – What You Need to Know

Fasting, the abstinence from food or drink for a set period, has been around for centuries, practiced in many cultures and religions for spiritual or health reasons.

But lately, it’s experiencing a surge in popularity as a dietary approach.

There are various ways to fast, from complete abstinence for a day or two to restricting your eating window within a specific timeframe.

Now, I’ll admit, I wasn’t always a believer in fasting. In fact, the idea of going without food for any extended period initially seemed daunting.

But after experiencing the positive effects firsthand, I became a fan.

Understanding Fasting

Fasting, in its simplest form, is taking a break from food – a deliberate period of abstinence that can range from a few hours to several days.

But beneath this simple concept lies a powerful biological process.

There are two main categories of fasting:

  • Complete Fasting: This involves abstaining from all food and calorie-containing beverages. Water, black coffee, and unsweetened tea are typically allowed.
  • Intermittent Fasting (IF): This is a more flexible approach that cycles between eating windows and fasting windows. Popular IF methods include the 16/8 method (fasting for 16 hours and eating within an 8-hour window) or the 5:2 diet (eating normally for 5 days and restricting calories on 2 non-consecutive days).

The science behind fasting is quite fascinating. When we eat, our bodies are constantly processing and burning calories for energy.

However, during a fast, this process shifts. As blood sugar levels drop, the body taps into stored glycogen (sugar) for fuel.

Once glycogen stores are depleted, which typically takes around 12 hours, the body enters a state called ketosis.

In ketosis, the liver starts producing ketones, an alternative energy source derived from fat breakdown.

This metabolic switch is believed to be responsible for many of the potential benefits associated with fasting.

Studies suggest that fasting may:

  • Enhance cellular repair: Fasting can trigger a process called autophagy, where the body essentially cleans the house by removing damaged cells and promoting the growth of new ones.
  • Improve insulin sensitivity: Fasting can help regulate blood sugar levels and may be beneficial for those with prediabetes or type 2 diabetes.
  • Promote weight loss: By burning stored fat for energy, fasting can contribute to weight management, although a healthy diet and exercise are still crucial for long-term success.
  • Reduce inflammation: Research suggests that fasting may have anti-inflammatory properties, potentially reducing the risk of chronic diseases.

The 36-Hour Fast

Now, let’s delve into the specific practice that sparked my interest in fasting – the 36-hour fast, also known as the “monk fast.”

This type of fasting falls under the umbrella of intermittent fasting and involves abstaining from all food for a 36-hour period, typically from dinner one day to breakfast the next day (plus another 12 hours).

While it may seem intense, the potential benefits can be quite compelling.

Benefits of a 36-Hour Fast

  • Enhanced Weight Loss:  A 36-hour fast provides a significant window for your body to tap into stored fat reserves for energy. This extended period in ketosis can potentially lead to greater weight loss compared to shorter fasting windows.
  • Cellular Renewal Boost:  Research suggests that longer fasting durations may trigger autophagy to a greater extent. This cellular clean-up process can promote overall cellular health and potentially slow down aging.
  • Improved Insulin Sensitivity: By giving your digestive system a break and allowing blood sugar levels to regulate naturally, a 36-hour fast can further enhance your body’s ability to manage insulin.

My Experience

I can personally attest to the positive effects of a 36-hour fast. Initially, hunger pangs were present, especially around the 24-hour mark.

However, by staying hydrated with water and unsweetened tea, the discomfort subsided.

More importantly, I experienced a newfound mental clarity and focus throughout the fast.

By the time I broke my fast with a healthy meal, I felt lighter, both physically and mentally.

Important Considerations

  • Hydration is Key:  During a 36-hour fast, staying adequately hydrated is crucial. Aim to drink plenty of water throughout the fasting window.
  • Listen to Your Body: While some people breeze through a 36-hour fast, others may experience fatigue, headaches, or irritability. It’s essential to listen to your body and break the fast if you feel unwell.
  • Gradual Reintroduction:  Don’t jump back into heavy meals after a long fast. Opt for easily digestible foods and gradually increase portion sizes over the next day.

The 72-Hour Fast

A 72-hour fast, as the name suggests, involves abstaining from eating for three full days.

While this may seem like a daunting task, it’s not as unattainable as it might initially appear, especially with gradual practice and proper preparation.

The benefits of a 72-hour fast are profound and include:

  1. Deep Ketosis: After about 48 hours of fasting, your body enters a state of deep ketosis, where it’s efficiently burning fat for energy. This can lead to significant weight loss.
  2. Autophagy: Autophagy, the body’s natural process of cleaning out damaged cells, is significantly increased during a 72-hour fast. This can lead to numerous health benefits, including anti-aging effects and disease prevention.
  3. Immune System Reset: Research suggests that a 72-hour fast can help reset the immune system, aiding in the regeneration of immune cells.
  4. Mental Clarity: Just like with a 36-hour fast, many people report increased focus and mental clarity during a 72-hour fast.
  5. Improved Insulin Sensitivity: Extended fasting can help improve insulin sensitivity, which is beneficial for people with or at risk of developing type 2 diabetes.

While I haven’t personally experienced a 72-hour fast, I’ve gathered insights from various sources, including scientific studies and anecdotes from those who have successfully completed such fasts.

Many report a sense of accomplishment after completing the 72-hour fast.

They describe experiencing heightened mental clarity, improved digestion, and a feeling of lightness and increased energy.

However, it’s important to note that a 72-hour fast should be approached with caution and always under medical supervision.

It’s not suitable for everyone, and if you’re considering it, you should consult with a healthcare professional.

Comparing 36-Hour and 72-Hour Fasts

Both 36-hour and 72-hour fasts offer potential benefits, but they come with varying degrees of intensity and suitability.

Here’s a breakdown to help you decide which might be a better fit for you:

Intensity and Difficulty

  • 36-Hour Fast: This is a more manageable option for beginners or those new to fasting. While you’ll experience some hunger pangs, most people can complete a 36-hour fast without significant discomfort.
  • 72-Hour Fast: This is a much more demanding approach. Fatigue, headaches, and irritability are more likely, and electrolyte imbalances can become a concern. It requires a higher level of commitment and preparation.

Considerations and Suitability

  • 36-Hour Fast: A good starting point for those new to fasting. It’s generally well-tolerated with fewer side effects compared to a 72-hour fast. It can be incorporated into your routine more easily, perhaps once or twice a week.
  • 72-Hour Fast: Due to the extended duration, this is best for experienced fasters or those under close medical supervision. It can be more challenging and lead to stronger side effects like fatigue, headaches, and electrolyte imbalances. It’s not recommended for frequent repetition.

Choosing the Right Fast

Here’s a quick guide to help you decide:

  • For Beginners: Start with a 36-hour fast and assess your body’s response.
  • For Weight Loss: Both can be effective, but a 72-hour fast might offer slightly more fat-burning potential. Remember, diet and exercise are still crucial for long-term weight management.
  • For Improved Cellular Health: Both can stimulate autophagy, but a 72-hour fast might have a more pronounced effect.
  • For Overall Health: If you have pre-existing health conditions, a 36-hour fast might be a safer option. Always consult your doctor before attempting a 72-hour fast.

Common Misconceptions and Mistakes

Fasting has gained traction, but with its rise comes a wave of misconceptions and mistakes.

Here’s how to separate fact from fiction and ensure a safe and effective fasting experience:

Myth #1: Fasting is Starving Yourself:

Fact: Fasting is a controlled period of abstinence, not deprivation. Water, black coffee, and unsweetened tea are typically allowed. Your body adapts by utilizing stored energy during a fast.

Myth #2: Fasting is Only for Weight Loss:

Fact: While weight management can be a benefit, fasting offers a wider range of potential advantages, including improved cellular health, enhanced insulin sensitivity, and reduced inflammation.

Myth #3: You Can Binge Eat After a Fast:

Fact: Breaking a fast with heavy meals can lead to digestive discomfort. Opt for easily digestible foods and gradually increase portion sizes over a few days.

Expert Advice to Avoid Mistakes:

  • Don’t Go Cold Turkey:  If you’re new to fasting, begin with shorter durations (12-16 hours) and gradually increase the fasting window as your body adjusts.
  • Focus on Quality Over Quantity: During eating windows, prioritize nutrient-rich whole foods over processed options. This ensures your body gets the vitamins and minerals it needs.
  • Listen to Your Body:  Fasting shouldn’t be miserable. If you experience severe headaches, dizziness, or prolonged fatigue, break the fast and consult a doctor.
  • Hydration is Key: Dehydration is a common concern during fasts. Ensure you drink plenty of water throughout the fasting window.
  • Fasting Isn’t a One-Size-Fits-All Approach: Certain health conditions, pregnancy, and breastfeeding can make fasting unsuitable. Always consult your doctor before attempting any fasting protocol.


Fasting, when done correctly, can offer numerous health benefits, from weight loss and improved insulin sensitivity to enhanced mental clarity and cellular repair.

However, it’s not a one-size-fits-all solution, and what works best for one person might not work as well for another.

It’s important to listen to your body, start slow, and always consult with a healthcare professional before embarking on a fasting regimen.


Hi there, I'm Pranay, a fitness enthusiast who loves working out regularly and staying in shape. I'm passionate about health and fitness, and I'm always on the lookout for new and exciting ways to stay active and healthy.

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