What Is Prolonged Fasting and How Does It Work?
Prolonged fasting is defined as the complete abstention from caloric foods and beverages for an extended period, typically 48 hours or more, allowing only water, unsweetened tea, or black coffee. This practice, which has been observed for centuries across various cultures and religions, promotes cleansing and regeneration processes in the body.
There are different types of fasting such as water fasting, juice fasting, or religious fasts, but in this article, we’ll focus on a 3 day water fast and its health benefits.
While most people, especially younger generations, don’t fast regularly, this practice offers numerous benefits that we’ll explore in detail. Unlike intermittent fasting, which alternates between periods of eating and fasting (a topic we’ll cover in another article), here we’re talking about abstaining from food for an extended period.
Benefits of Prolonged Fasting
A three-day fast triggers a deep process of cellular cleansing and regeneration. During this time, the body activates mechanisms like autophagy and apoptosis, which clear out cellular waste and promote renewal. Autophagy, a process that earned Yoshinori Ohsumi the Nobel Prize in Medicine in 2016 (1), recycles damaged cellular components, while apoptosis removes defective cells, reducing inflammation and oxidative stress.
Fasting can also reduce the buildup of senescent cells, which contribute to aging and chronic inflammation (2). However, fasting isn’t something you dive into overnight, it’s a habit you build gradually, much like training a muscle at the gym.
If you’re new to fasting, it’s best to start with intermittent fasting using the 16:8 method (16 hours of fasting with an 8-hour eating window, for example, eating from 10:00 a.m. to 6:00 p.m.), then progress to a full day, and gradually increase the duration.
Additional Benefits of Fasting
At the 24-hour mark, intestinal stem cells regenerate, improving gut health and strengthening the immune system (3)(4), a 2021 study published in Nature Communications found that prolonged fasting increases the diversity of the gut microbiota, reducing systemic inflammation (5). Additionally, a 24-hour fast can lower levels of TMAO (6), a compound linked to cardiovascular risk, according to preliminary research.
Fasting also benefits the brain: it boosts the production of BDNF (brain-derived neurotrophic factor), a protein that protects against neurodegenerative diseases and enhances mental clarity (7). Another study found that a 48-hour fast increases BDNF expression in skeletal muscle by approximately 3.5 times (8), which could contribute to systemic benefits, meaning it can improve the health of your entire body, not just one specific area, which we found fascinating.
Moreover, animal studies, such as a 2019 study, suggest that fasting activates longevity pathways like sirtuins, slowing down aging (9). During fasting, growth hormone and testosterone levels also rise, reducing inflammation and improving overall health (10).
The 3-Day Water Fasting Process
- 0-12 Hours: After your last meal, insulin levels are elevated. As the hours pass, insulin begins to drop, which can enhance insulin sensitivity over time—a key factor for metabolic health.
- 12-18 Hours: The body enters ketosis, a state where it shifts from using glucose to burning fat for energy, promoting fat loss.
- 24-48 Hours: Autophagy and apoptosis intensify. Autophagy cleans and repairs damaged parts within cells, while apoptosis removes entirely defective cells, reducing the buildup of senescent cells that contribute to inflammation and aging.
- 48-54 Hours: Growth hormone levels rise, aiding tissue repair, reducing inflammation, and promoting cellular regeneration.
- 54-72 Hours: Insulin sensitivity improves significantly, and autophagy reaches its peak. Additionally, the circulation of stem cells increases, supporting tissue regeneration and a “reset” of the immune system.
Inspiration to Fast
The Honorable Elijah Muhammad shared a thought-provoking insight on fasting: “If you ate a meal every other day, you’d only get sick one day every 4 or 5 years, to eliminate that day of illness, fast for 72 hours, and there won’t be enough poison in your body to ever make you sick.” With this, he suggests that many diseases are linked to overeating, and fasting more can improve our health.
Historical Insights on Fasting
Fasting has been practiced for centuries across various cultures, such as during Ramadan in Islam, Yom Kippur in Judaism, and even by Jesus, who fasted for 40 days in the desert seeking spiritual clarity and strength, often associated with both spiritual and physical benefits.
Considerations and Precautions
Prolonged fasting isn’t for everyone, if you have conditions like uncontrolled hypothyroidism, diabetes (especially if you’re on insulin or medications like glimepiride) or adrenal issues, you should avoid fasting without medical supervision, as you could experience low blood sugar or electrolyte imbalances.
Other side effects may include dizziness, fatigue, or dehydration, particularly if you don’t stay properly hydrated, we always recommend consulting a healthcare professional knowledgeable about fasting before starting.
Strategies to Get Started
Don’t jump straight into a 3-day fast. If it’s your first time, start by eliminating foods like dairy, grains, and cereals for a few days. Then, try shorter fasts or light juices before attempting a water fast. During the fast, stay hydrated with water and electrolytes (like high-quality sea salt), and listen to your body.
If you’ve never fasted before, ease into it. A few days before starting, let your body rest by skipping dinner and limiting your eating to daylight hours.
How to Break Your Fast Safely
Breaking a fast properly is just as important as the fast itself. After 72 hours, it’s generally recommended to avoid eating large amounts of food right away to prevent refeeding syndrome, which can cause electrolyte imbalances.
On the other hand, some fasting experts suggest a different approach, recommending breaking the fast with a hearty meal that includes a generous portion of meat. They argue this mirrors the habits of early humans who, after days of scarcity, consumed a protein and fat-rich meal upon hunting prey, providing immediate energy and essential nutrients for recovery.
If it’s your first time, start by breaking the fast with broths (bone broth is an excellent choice), light juices, or gentle fruits like bananas or cooked apples. After 24 hours, reintroduce small nutritious meals like eggs, avocado or fish, listen to your body to find the best way to break your fast based on your personal needs.
Conclusion: Embrace the Power of Fasting to Transform Your Health
Prolonged fasting is a powerful tool to rejuvenate your body, enhance metabolic health, and strengthen your immune system. From cellular regeneration to mental clarity, its benefits are profound and backed by science. However, the key is to approach it gradually and safely, always listening to your body and seeking medical guidance if you have health conditions.
Start today with small steps—perhaps by skipping dinner or trying a 16, 18 or 24-hour fast and discover how fasting can transform your life, leading to a state of well-being and vitality that radiates from within, are you ready to give your body the rest it deserves?
