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The Comprehensive Guide to 24-72 Hour Fasting

The Comprehensive Guide to 24-72 Hour Fasting

Feb 27, 2024

The Comprehensive Guide to 24-72 Hour Fasting

This guide by Thomas DeLauer is tailored to those seeking to understand and successfully undertake a fast that extends beyond the 24-hour mark, venturing into the 48 to 72-hour territory—a domain distinctly separate from the popular intermittent fasting practice.

Introduction to Longer-Term Fasting

Fasting is a practice as ancient as time, with a rich tapestry of cultural and health-related significance. In the modern era, it has been redefined and embraced as a powerful tool for promoting weight loss, enhancing metabolic health, and fostering cellular renewal. Longer-term fasting, typically defined as fasting for periods ranging from 24 to 72 hours, pushes the boundaries further, aiming to elicit profound changes within the body's cells and systems. Contrary to the shorter fasting windows of intermittent fasting, longer-term fasting is a deeper dive that requires careful preparation, execution, and breaking protocols.

This guide will meticulously walk you through the intricacies of longer-term fasting, covering the benefits, preparation, frequency, exercise, breaking the fast, and supplementary considerations. It is a beginner-friendly compass, pointing you toward the ultimate goal of a successful and healthful fasting experience.

Understanding the Benefits

The allure of longer-term fasting lies not just in its fat loss capabilities but also in its potential to enhance overall health and longevity. As your body transitions into a state of fasting, it begins to utilize fat reserves for energy, a process known as lipolysis. However, the true magic unfolds as fasting stimulates the production of stem cells, as demonstrated by research at the University of Southern California. These stem cells regenerate and evolve into more robust versions of themselves, fortifying the body's ability to heal and rejuvenate.

Moreover, fasting extends the lifespan of cells by preserving telomeres—the protective caps of our chromosomes—through the increased production of telomerase. The upregulation of autophagy, the body's cellular recycling system, alongside the surge in ketone production, further adds to the therapeutic cascade. High levels of ketones not only serve as an energy source but also play a pivotal role in reducing inflammation. Lastly, cognitive enhancements are amplified during a longer-term fast, as evidenced by increased levels of brain-derived neurotrophic factor (BDNF), which fosters neuronal growth and mental acuity.

Preparing for Your Fast

Transitioning Your Diet

In the days leading up to your fast, consider adopting a low-carbohydrate or ketogenic diet. This approach will prime your body to utilize fats as its primary fuel source, reducing hunger and facilitating the production of ketones right from the onset of your fasting period. Aim for a 3 to 5-day transition for best results.

Hydration and Electrolytes

Prior to fasting, focus on hyperhydration—drinking an abundance of water—and increasing your sodium intake. These steps are crucial in preventing dehydration and mineral imbalances once your body begins to shed excess water weight due to lower insulin levels during the fast.

During the Fast: Consumption and Activity

What to Consume

While on a longer-term fast, your intake should be limited to:

  • Black coffee: A known stimulant that may help suppress appetite.
  • Water: Essential for maintaining hydration.
  • Tea: Green tea, particularly matcha, is recommended for its catechins and theanine, which can aid in fat burning and provide a calming effect.
  • Apple cider vinegar: A popular choice for its potential health benefits.
  • Salt: A small amount can help with electrolyte balance.


Engage in low-intensity exercise during your fast to mobilize glycogen stores and maintain muscle activity without triggering an anabolic response that could counteract the fasting state. Light weight training and gentle cardio are encouraged.

Breaking the Fast

When it's time to break your fast, opt for a lean protein meal in the evening and refrain from eating anything else until the next morning. This strategy allows your digestive and immune systems to gently wake from their fasting-induced slumber and minimizes the risk of adverse reactions to foods.

Frequency of Longer-Term Fasting

For a sustainable and effective fasting regimen, consider a 48 to 72-hour fast once per month. This frequency allows you to reap the cumulative benefits of fasting without overburdening your body or lifestyle.

Supplements During Fasting

Avoid fat-soluble vitamins and antioxidant supplements during the fast, as they can disrupt the beneficial stress your cells undergo. Stick to the approved consumption list, and you may introduce your regular supplements after breaking the fast.

Final Thoughts and Further Resources

Longer-term fasting is a dance between discipline and biology, where each step is carefully curated to lead to a symphony of health benefits. By adhering to the guidance provided, you will have laid the groundwork for a successful fasting experience. Remember to consult with a healthcare professional before embarking on any significant dietary changes, especially if you have underlying health conditions or are on medication.


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