Intermittent Fasting and the Longest Recorded Extended Fasts: How Did They Do It?

Intermittent fasting (IF) is a practice that involves alternating periods of eating with periods of fasting. While most intermittent fasting regimens are relatively short, lasting between 12 to 24 hours, extended fasting involves going without food for much longer periods — days, weeks, or even months. The idea of extended fasting might sound extreme to many, but it has been practiced for centuries for various reasons, including religious observance, spiritual cleansing, and health benefits. In this blog post, we will explore some of the longest recorded extended fasts in history, how individuals accomplished them, and the potential benefits and risks associated with prolonged fasting.

1. The Longest Recorded Fast: Angus Barbieri’s 382-Day Fast

One of the most famous cases of extended fasting is that of Angus Barbieri, a 27-year-old man from Scotland who fasted for 382 days from June 1965 to July 1966. At the start of his fast, Angus weighed 456 pounds (207 kg) and was under medical supervision throughout the entire period. His goal was to achieve significant weight loss and improve his overall health.

How Did He Do It?
Angus consumed only non-caloric fluids such as water, tea, coffee, and electrolytes during his fast. He also took daily multivitamins to ensure he met his basic nutritional needs. Under the supervision of his doctors, he received regular check-ups to monitor his vital signs, blood glucose levels, and electrolyte balance. By the end of the fast, Angus had lost 276 pounds (125 kg) and weighed 180 pounds (82 kg).

What Can We Learn from This?
Angus Barbieri's fast demonstrates that extended fasting can result in substantial weight loss. However, it also emphasizes the importance of medical supervision and supplementation to prevent nutrient deficiencies and maintain electrolyte balance. His case remains one of the most extreme examples of fasting, and it should be noted that such prolonged fasting should only be done under strict medical guidance .

2. The 50-Day Fast by David Blaine

David Blaine, an American magician and endurance artist, completed a 50-day fast in 2003 as part of a public endurance stunt. Blaine was suspended in a transparent box over the River Thames in London, where he consumed only water during the 50-day fast. The fast attracted significant media attention and was documented as one of Blaine’s most challenging endurance feats.

How Did He Do It?
Blaine prepared for the fast with the help of medical professionals who monitored his health throughout the process. He only drank water and was closely observed to ensure his safety. Blaine lost a significant amount of weight, approximately 25 percent of his body weight, and suffered symptoms such as dizziness, fatigue, and muscle atrophy. Despite the challenges, he completed the fast without major medical complications.

What Can We Learn from This?
David Blaine's fast shows that even shorter extended fasts, like his 50-day fast, can place a significant strain on the body. Proper preparation and medical monitoring are essential to minimize health risks. While Blaine successfully completed his fast, he experienced several adverse effects, highlighting the potential dangers of extended fasting without adequate supervision .

3. Dr. Michael Mosley’s 5:2 Fast and Longer Fasts

Dr. Michael Mosley, a British journalist and doctor, popularized the 5:2 intermittent fasting method, which involves eating normally for five days a week and consuming only about 500-600 calories on the other two days. Dr. Mosley has also experimented with longer fasts and has documented his experiences in his writings and television programs.

How Did He Do It?
Dr. Mosley used extended fasts of up to several days to explore the health benefits and challenges associated with fasting. He emphasizes the importance of hydration, maintaining electrolyte balance, and easing back into eating after a fast to prevent refeeding syndrome, a potentially dangerous condition where electrolyte imbalances occur after a prolonged fast. Mosley focuses on preparation, ensuring adequate nutrient intake before the fast, and closely monitoring the body's response throughout .

What Can We Learn from This?
Dr. Mosley’s experience highlights the importance of understanding one’s body and approaching extended fasting with caution and preparation. His focus on shorter fasts and the use of structured intermittent fasting methods, like the 5:2 diet, shows a safer and more sustainable approach to incorporating fasting into everyday life for health benefits.

4. Fasting in Therapeutic Contexts: The Buchinger Clinic Experience

The Buchinger Wilhelmi Clinic in Germany is a world-renowned center for therapeutic fasting and integrative medicine. Patients at the clinic undergo supervised fasts ranging from several days to weeks, with an emphasis on healing, detoxification, and disease prevention.

How Do They Do It?
Patients at the Buchinger Clinic participate in guided fasts where they consume small amounts of vegetable broth, juices, herbal teas, and water. The fasting programs are tailored to individual needs, with medical professionals monitoring vital signs, blood pressure, and other health markers. The clinic incorporates practices such as light physical activity, yoga, meditation, and spa treatments to support the body's natural detoxification processes.

What Can We Learn from This?
The Buchinger Clinic experience emphasizes the therapeutic benefits of fasting under professional supervision. It shows that extended fasting can be a safe and effective tool for promoting health when done in a controlled and supportive environment .

5. Long-Term Fasting in Religious and Cultural Practices

Extended fasting is not limited to health or endurance challenges; it is also a part of many religious and cultural practices. For example, Ramadan involves fasting from dawn to sunset for 29 to 30 days, and Lent in Christianity involves fasting or giving up certain foods for 40 days. In Jainism, extended fasting is practiced as a spiritual exercise.

How Do They Do It?
Religious and cultural fasting often includes spiritual preparation, communal support, and a focus on mindfulness and spiritual growth. These fasts are typically shorter than medically supervised fasts but still provide insight into how extended fasting can be incorporated into daily life with a focus on mental and emotional well-being.

What Can We Learn from This?
These practices show that fasting is not only about physical health but can also have profound spiritual and psychological benefits. Fasting in a community or spiritual context can provide support and motivation, making the fasting experience more meaningful and manageable .

Conclusion

Extended fasting, whether for health, endurance, or spiritual reasons, offers a unique look into the human body's resilience and adaptability. The longest recorded fasts demonstrate that, with proper medical supervision, hydration, and supplementation, the human body can safely endure extended periods without food. However, these fasts should not be attempted without professional guidance due to the potential risks involved. For most people, shorter intermittent fasting regimens provide a more sustainable and safe approach to harnessing the benefits of fasting.

Sources:

1. Stewart, W. K., & Fleming, L. W. (1973). Features of a Successful Therapeutic Fast of 382 Days' Duration. Postgraduate Medical Journal, 49(569), 203-209.
2. Varady, K. A., & Hellerstein, M. K. (2007). Alternate-Day Fasting and Chronic Disease Prevention: A Review of Human and Animal Trials. American Journal of Clinical Nutrition, 86(1), 7-13.
3. Mosley, M. (2013). The Fast Diet: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting. Atria Books.
4. Buchinger, O., & Lützner, H. (2010). Therapeutic Fasting: The Buchinger Amplius Method. Georg Thieme Verlag.
5. Finnell, J. S., Saul, B. C., Goldhamer, A. C., & Myers, T. R. (2013). Is Fasting Safe? A Chart Review of Adverse Events During Medically Supervised, Water-Only Fasting. BMC Complementary and Alternative Medicine, 13(1), 1-5.