Prolonged fasting: the people who pushed its limits

In 1965, a Scottish man named Angus Barbieri stopped eating. He continued for 382 days and lost roughly 125 kilograms.

Nearly two thousand years earlier, according to the Gospels, Jesus spent forty days fasting in the wilderness before beginning his public ministry.

Centuries before that, according to Buddhist tradition, a young seeker named Siddhartha Gautama practiced extreme austerity, nearly starved himself, and reached an unexpected conclusion: he needed to eat something.

Three men, three different aims. One wanted to lose weight. Another sought spiritual preparation. The third discovered that depriving himself of food was not bringing him closer to the insight he wanted.

These are not isolated cases. Throughout history, people have fasted for extraordinary lengths of time in pursuit of God, health, liberation, political change, endurance, or an audience. Some reported profound insights or striking physical changes. Others became influential teachers or symbols. A few paid with their lives.

What makes the stories compelling is not simply how long they went without food. It is what they believed they were doing, what they experienced, and what they actually gained.

The gap between those three things is where the interesting lessons sit.

1. Forty days in search of God

Moses

Deuteronomy describes Moses spending forty days and forty nights on Mount Sinai receiving the tablets of the covenant, consuming neither food nor water. A second forty-day period follows the incident of the golden calf.

The purpose, within the narrative, is communion with God, reception of the law, and intercession for the people. The result is foundational to Jewish religious history.

Interestingly, Moses returned from his first encounter to discover that the people had already begun worshipping a golden calf. Apparently, even direct communication with God didn’t guarantee that everyone back home would follow the instructions.

The account is a story of divine encounter, not a clinical study of human survival without water.

Elijah

In 1 Kings 19, Elijah, exhausted after confronting the prophets of Baal, is strengthened by food provided by an angel and travels forty days and nights to Horeb.

At the mountain he encounters wind, earthquake, and fire, yet the divine presence is associated with a quiet voice that follows.

After all that drama, the important message arrives quietly.

The story links hardship, solitude, and attentive waiting with a renewed sense of prophetic direction. It also offers an observation that extends beyond religious practice: sometimes the most important thing isn’t the loudest thing competing for our attention.

Jesus

The Gospels describe Jesus fasting forty days in the wilderness. Luke states that he ate nothing.

The central drama is the testing of desire, power, and vulnerability. When challenged to turn stones into bread, he refuses, presenting the refusal as a declaration that physical appetite does not define the whole of human life.

Other temptations concern political authority, spectacle, and the misuse of power. It is an interesting collection of challenges, particularly considering how frequently people have pursued all three throughout history.

Within Christian tradition, the wilderness fast became a model of preparation, self-discipline, and resistance to temptation.

The lesson extends beyond fasting: the physical sensation of wanting something does not automatically mean that obtaining it is the most important action.

2. The ascetics who took fasting further

Macarius of Alexandria

By the fourth century, fasting was central to Egyptian monastic life.

Palladius’ Lausiac History records that Macarius visited a Pachomian monastery where the monks already followed demanding disciplines—some eating once a day, others every second day or every five days.

Macarius, according to the account, stood through the forty days of Lent, working and praying, and ate only a few cabbage leaves on Sundays.

The other monks were disturbed enough to complain.

It’s rather amusing to imagine an entire monastery of dedicated ascetics asking their superior to remove a visitor because he was making their already difficult lives look embarrassingly comfortable.

The story illustrates extraordinary discipline. But the Desert Fathers themselves also warned that the ability to fast could become another form of status or pride.

If the objective is humility, becoming the monastery’s undisputed fasting champion introduces an interesting complication.

Nicholas of Flüe

The Swiss hermit Nicholas of Flüe, known as Brother Klaus (1417–1487), left his wife and ten children in 1467, with his wife’s consent, to pursue a contemplative life in the Ranft valley.

Tradition holds that he subsequently lived approximately nineteen or twenty years without ordinary food, sustained by divine grace associated with the Eucharist.

Contemporary accounts took the claim seriously enough that authorities investigated, although continuous observation capable of establishing it physiologically does not exist.

What is historically clearer is his influence.

Politicians and ordinary people sought his counsel, and he is remembered for helping resolve tensions at the Diet of Stans in 1481.

There is something wonderfully paradoxical about a man who withdrew from society only to become one of the people society most wanted to consult.

His contemplative withdrawal produced a form of moral authority that others found useful. Whether his extraordinary fasting reputation created that authority, symbolized it, or simply accompanied it is a separate question.

Mahavira

In Jain tradition, Mahavira is described as spending roughly twelve and a half years in severe asceticism that included extended fasting and meditation.

The goal was not improved health but liberation from karmic bondage and attachment.

Jain teaching presents hunger as an opportunity to examine desire and aversion rather than something that must always be removed.

The related practice of sallekhana—progressive reduction of food near the end of life under specific spiritual conditions—aims at equanimity, not therapeutic benefit.

The distinction from modern fasting culture is striking.

Someone fasting today may be trying to improve their body. Mahavira’s practice was directed toward becoming free from identification with its demands.

The philosophy asks whether freedom might arise from becoming less governed by desire itself.

3. The Buddha who discovered he needed to eat

According to early Buddhist texts, Siddhartha Gautama experimented with extreme austerity.

The Mahāsaccaka Sutta describes him consuming tiny quantities of broth until his body was severely wasted. His ribs protruded, his spine became visible, and ordinary movement became difficult.

The practice did not produce the awakening he sought.

He remembered an earlier meditative experience characterized by calm rather than deprivation, decided to eat solid food again, and lost the admiration of companions who had valued his severity.

Apparently, eating rice was enough to ruin a perfectly respectable reputation for extreme spirituality.

The decision became central to the Middle Way: rejection of both indulgence and self-mortification as ultimate paths.

Buddhist traditions retained disciplined eating, but the Buddha rejected the assumption that more severe deprivation necessarily yields more profound insight.

This is an especially interesting lesson for modern fasting culture, where longer and harder are often assumed to mean better.

Sometimes the next step is not to push harder.

Sometimes it is to recognize that the method has stopped serving the purpose—and then eat some rice.

4. Fasting for the body

Upton Sinclair

In The Fasting Cure (1911), American writer Upton Sinclair described struggling with digestive trouble, headaches, and weakness, then experimenting with fasts of several days to nearly two weeks.

He reported an initial period of hunger followed by reduced appetite, the disappearance of headaches, and a striking increase in mental clarity that allowed him to read and write with renewed energy.

Sinclair was already famous for The Jungle, his novel exposing conditions in the meatpacking industry.

Having written about what happened when people produced food, he had now become fascinated by what happened when they stopped eating it.

His book mixes personal observation with enthusiastic advocacy and testimonials. It records a dramatic subjective experience; it does not constitute controlled evidence that fasting cured the conditions he believed it treated.

But his enthusiasm is understandable.

When someone experiences a substantial improvement in how they feel, they naturally want to understand why.

Sinclair went a step further and wrote an entire book about it.

Henry S. Tanner

In 1880, American physician Henry S. Tanner undertook a public forty-day fast in New York.

Spectators, journalists, and doctors observed him. He completed the period, collected a $1,000 prize, and became a figure of medical and popular curiosity.

Contemporary reports and photographs survive, including portraits taken before the fast and after fourteen and twenty-one days.

Afterward, Tanner briefly exhibited himself at a New York museum, where visitors could reportedly pay fifty cents to see the man who had gone forty days without food.

Humanity had successfully turned not eating into a spectator sport.

The experiment demonstrated that one individual under those conditions could survive forty days without food. It did not prove therapeutic claims for prolonged fasting in general.

But it certainly gave the medical establishment something to argue about.

Angus Barbieri

In 1965, twenty-seven-year-old Angus Barbieri, weighing approximately 207 kilograms, began a medically supervised fast that lasted 382 days.

He consumed noncaloric fluids and received vitamin and occasional mineral supplementation while remaining ambulatory under outpatient monitoring.

A 1973 paper in the Postgraduate Medical Journal documented the case. His weight fell to around 82 kilograms.

Blood chemistry showed marked changes, including very low glucose at times, yet he remained conscious and functioning. Follow-up recorded that he maintained a substantially lower weight.

His fast lasted longer than an entire calendar year. His physicians described the remarkable experiment in seven journal pages.

The case remains one of the most striking demonstrations of human metabolic adaptation ever published.

It also involved an individual with exceptionally large energy reserves and ongoing medical oversight, making it a highly specific case rather than a general model for weight management.

Still, Barbieri set out to accomplish something measurable.

And he accomplished it on a scale few people would have imagined possible.

Friedrich Klapdor: forty-five years of repeated fasting

In 2024, researchers published a case report about Friedrich Klapdor, a ninety-two-year-old German man who had undertaken roughly three-week modified Buchinger fasts almost every year for forty-five years.

He completed forty-six fasting periods in total.

These were medically supervised fasts providing approximately 250 calories per day through juice, vegetable soup, and honey—not complete water-only fasts.

Klapdor began fasting in 1970, initially as a personal challenge. He continued because he reported improvements in his physical and emotional well-being.

There was another interesting change: after his first fast, he stopped smoking and never resumed.

He did, however, continue enjoying approximately half a litre of beer a day during later life.

Apparently, his approach to personal improvement didn’t require eliminating every pleasure.

At ninety-two, Klapdor remained independently mobile and performed well on physical and cognitive assessments. An epigenetic-age analysis estimated his biological age at 5.9 years below his chronological age.

The study was conducted and funded by researchers associated with the clinic where he fasted, so it cannot establish that fasting caused his longevity or health status.

What makes his story interesting is the consistency.

Unlike Barbieri, Klapdor wasn’t undertaking a single extraordinary endurance event. He made periodic fasting part of his life for decades because he believed it benefited him.

And when the transition into longer fasts became more difficult at age eighty-five, he stopped doing them.

That may have been one of his more sensible decisions.

5. Will, protest, and spectacle

César Chávez

American labour organizer César Chávez undertook major fasts of twenty-five days in 1968, twenty-four days in 1972, and thirty-six days in 1988.

They combined religious devotion with public advocacy—first to reinforce nonviolence within the farmworkers’ movement, later to draw attention to pesticide exposure.

During his first major fast, Chávez stayed in a windowless room at the Forty Acres complex in California, leaving primarily to attend daily Mass.

When the fast ended, thousands gathered, including Senator Robert F. Kennedy.

The refusal to eat communicated seriousness in a way speeches alone did not.

Chávez’s fasting also had a deeply personal dimension. He described it as a spiritual practice intended to strengthen his own commitment as well as communicate with others.

Fasting cannot prove a political position correct, but it can make conviction visible.

Terence MacSwiney

In 1920, Terence MacSwiney, the Lord Mayor of Cork, began a hunger strike in British custody and continued for seventy-four days until his death.

The act was resistance, not a health experiment.

Letters and contemporary accounts record his progressive physical deterioration. During his final days, he continued writing to colleagues and supporters while family members and his chaplain remained close to him.

His death intensified international attention to the Irish independence movement and entered political memory as a symbol of commitment.

There is a striking contrast between his increasing physical weakness and the growing international attention his protest attracted.

Hunger is ordinarily a powerful incentive to self-preservation.

MacSwiney refused that incentive for a cause he judged more important.

David Blaine

In 2003, endurance performer David Blaine spent forty-four days in a transparent box above the River Thames, consuming water but no food.

He lost roughly a quarter of his body weight.

The public watched the spectacle from below, while medical researchers eventually gained something rather more useful than an interesting view of a hungry magician.

During refeeding, researchers documented significant metabolic and hormonal changes, including low phosphate and fluid retention that required treatment.

They also observed changes in appetite-related hormones, including orexin-A, although the significance of those findings remained uncertain.

The event was spectacle and research opportunity at once.

Blaine demonstrated an extraordinary capacity for endurance, while the medical observations revealed that the body’s response to prolonged fasting continues well after eating resumes.

6. What did they actually gain?

The stories share the absence of ordinary food and little else.

Some outcomes are measurable: weight loss, changes in glucose, ketones, and hormones. Barbieri and Blaine provide unusually clear documentation. A physical change is not automatically a benefit, and one person’s result doesn’t guarantee another’s.

Some outcomes are subjective: Sinclair’s reported clarity, Klapdor’s sense of improved well-being, and the calm or alertness others describe. These experiences deserve attention, although they don’t yet allow reliable predictions of who will experience them or why.

Some outcomes are expressed in spiritual language—revelation, purification, freedom from attachment, communion, and humility.

These aren’t established by blood tests. That doesn’t make them meaningless.

A person may judge a period of fasting and prayer profoundly worthwhile even if their weight and laboratory values eventually return to baseline.

The meaning was never primarily metabolic.

Running through many of these accounts is a simple capacity: the ability to experience a strong biological signal—hunger—without immediately acting on it.

Religious ascetics may call it freedom from attachment. Someone changing eating habits may call it a different relationship with food. A political hunger striker may treat the refusal as evidence that a conviction outweighs comfort or survival.

The purposes aren’t morally equivalent, yet they reveal something about human agency.

We are influenced by needs and desires. We aren’t always required to obey every one of them immediately.

That capacity can be useful.

It can also be misapplied.

The Buddha’s most useful lesson may be that he recognized when willpower was being spent on the wrong result.

Further figures worth exploring

Individual	Reported practice	Why it remains interesting
Simeon Stylites	Extreme Lenten fasting	Early Christian public asceticism
Catherine of Siena	Severe repeated food restriction	Mysticism and the physical cost of extreme practice
Sadhu Haridas	Claimed forty days buried in 1837	Disputed yogic feat and nineteenth-century fascination with suspended animation
Giovanni Succi	Public fasts of approximately thirty to forty-five days	Professional fasting as entertainment and early experimental physiology
Stefano Merlatti	Reported fifty-day public fast	Medical controversy surrounding professional fasting performers
Bobby Sands	Sixty-six-day hunger strike in 1981	Political prison protest and international reaction
Daniel	Three weeks of restricted food	Biblical dietary restraint rather than complete fasting
Esther	Three-day communal fast	Fasting as collective appeal and preparation for difficult action

The extraordinary claims surrounding Sadhu Haridas are particularly interesting as historical accounts, although they cannot establish that he survived buried without oxygen, food, or water under the conditions described.

Conclusion

Fasting interrupts something so ordinary we rarely notice it.

Meals arrive, we eat, and the day continues.

When the pattern is deliberately broken, attention shifts. Hunger is felt differently. Time can feel altered. Food becomes either more or less important than usual.

The person is left with whatever motive brought them there.

Some sought better health. Some sought prayer, insight, or freedom from ordinary appetite. A few needed to demonstrate something to the world.

Their stories show that fasting can produce striking experiences and physical changes. They also show that duration alone reveals almost nothing about whether the experience was worthwhile.

Barbieri’s 382 days changed his body.

Sinclair’s shorter fasts changed his understanding of his health.

Klapdor’s repeated fasts became a valued part of his life for forty-five years.

The Buddha’s austerities changed his understanding of the spiritual path, partly because they failed.

And some of the most memorable religious fasters are remembered less for what happened to their bodies than for the teachings or influence associated with their practice.

The interesting question isn’t how long someone can avoid food.

It’s what happens when a person temporarily stops satisfying one of the body’s most persistent demands and directs attention elsewhere.

Sometimes something valuable appears.

Sometimes the method proves unhelpful.

And sometimes, after extraordinary effort, the most important discovery is that it’s time to eat.

Research and references

Religious and historical sources

1. The Hebrew Bible — Deuteronomy 9:9–18. Moses’ forty-day periods on Mount Sinai, including accounts of abstaining from food and water. https://www.biblegateway.com/passage/?search=Deuteronomy+9%3A9-18&version=NIV

2. The Hebrew Bible — 1 Kings 19: Elijah Flees to Horeb. Elijah’s journey and encounter with the divine presence. United States Conference of Catholic Bishops. https://bible.usccb.org/bible/1kings/19

3. The New Testament — Matthew 4 and Luke 4: Jesus Is Tested in the Wilderness. Gospel accounts of Jesus’ forty-day fast and temptation. https://www.biblegateway.com/passage/?search=Matthew+4%2CLuke+4&version=NIV

4. Palladius — The Lausiac History. Early Christian accounts of desert monasticism, including Macarius of Alexandria. English translation, 1918. https://www.tertullian.org/fathers/palladius_lausiac_02_text.htm

5. SWI swissinfo.ch — 1467: Nicholas of Flüe. Historical account of Nicholas leaving his family to become a hermit and his later influence on Swiss affairs. https://www.swissinfo.ch/eng/history/1467/6069754

6. BBC Religions — Jainism: Mahavira. Mahavira’s life, ascetic practices, and spiritual teaching. https://www.bbc.co.uk/religion/religions/jainism/history/mahavira.shtml

7. Majjhima Nikāya 36 — Mahāsaccakasutta: The Longer Discourse to Saccaka. The Buddha’s account of severe asceticism, emaciation, and return to solid food. Translation by Bhikkhu Sujato, SuttaCentral. https://suttacentral.net/mn36/en/sujato/

Modern accounts and medical research

8. Sinclair, Upton (1911). The Fasting Cure. First-person account of fasting for health and the author’s therapeutic claims. Project Gutenberg. https://www.gutenberg.org/ebooks/63293

9. Wellcome Collection — Henry S. Tanner Before the Start of His 40-Day Fast at Clarendon Hall, New York City (1880). Historical photograph and documentation of Tanner’s public fasting experiment. https://wellcomecollection.org/works/rzmy4c4t

10. The New Yorker (1934). Forty Days and Forty Nights. Historical narrative of Tanner’s fasting performance and the emergence of professional fasting exhibitions. https://www.newyorker.com/magazine/1934/05/05/forty-days-and-forty-nights

11. Stewart, W. K. & Fleming, L. W. (1973). Features of a Successful Therapeutic Fast of 382 Days’ Duration. Postgraduate Medical Journal, 49(569), 203–209. https://pubmed.ncbi.nlm.nih.gov/4803438/

12. Wilhelmi de Toledo, F., Grundler, F. & Mesnage, R. (2024). World’s Longest Medically Documented Repeated Fasting History in a 92 Years Old Man Who Fasted 21 Days Yearly for 45 Years: A Case Report. Journal of Integrative and Complementary Medicine, 30(5). https://doi.org/10.1089/jicm.2023.0352

13. Buchinger Wilhelmi Clinics (2024). The World’s Longest Clinical Documentation of Repeated, Long-Term Fasting. Identifies Friedrich Klapdor and provides background on his fasting history. https://www.buchinger-wilhelmi.com/en/worlds-longest-clinical-documentation-on-repeated-long-term-fasting/

14. Korbonits, M., Blaine, D., Elia, M. & Powell-Tuck, J. (2005). Refeeding David Blaine—Studies After a 44-Day Fast. New England Journal of Medicine, 353, 2306–2307. https://doi.org/10.1056/NEJM200511243532124

15. Korbonits, M., Blaine, D., Elia, M. & Powell-Tuck, J. (2007). Metabolic and Hormonal Changes During the Refeeding Period of Prolonged Fasting. European Journal of Endocrinology, 157(2), 157–166. https://pubmed.ncbi.nlm.nih.gov/17656593/

Political, social, and cultural sources

16. United States National Park Service — Places of César Chávez. Historic sites associated with Chávez’s leadership, religious fasting, and farmworker advocacy. https://www.nps.gov/articles/000/places-of-c%C3%A9sar-ch%C3%A1vez.htm

17. California Department of Education — Statement by César Chávez at the End of His 24-Day Fast for Justice, Phoenix, Arizona, June 4, 1972. Chávez’s own explanation of the purpose of his fasting. https://chavez.cde.ca.gov/ResearchCenter/DocumentDisplayRC.aspx?doc=6bec47%3Aea792358ca%3A-7ac7

18. Cork Public Museum — Suffering the Most: The 1920 Cork Hunger Strike. Documentation of Terence MacSwiney’s imprisonment, hunger strike, final letters, and death. https://www.corkcity.ie/en/cork-public-museum/exhibitions/past-present-exhibitions/suffering-the-most/

19. RTÉ Archives (2016). Bobby Sands Has Died 1981. Archival reporting from May 5, 1981, following Sands’ death after sixty-six days on hunger strike. https://www.rte.ie/archives/2016/0504/786070-death-of-bobby-sands/

Further historical research

20. Nieto-Galan, Agustí (2022). Useful Charlatans: Giovanni Succi and Stefano Merlatti’s Fasting Contest in Paris, 1886. Science in Context. Research on professional fasting, medical controversy, and public spectacle. https://www.cambridge.org/core/journals/science-in-context/article/abs/useful-charlatans-giovanni-succi-and-stefano-merlattis-fasting-contest-in-paris-1886/BF11A690B9F79591266854E41575A6BA

21. Chakraborty, Ayusman (2024). Hatha Yoga, Live Burial, and Human Hibernation: How the West (Mis)Conceptualized the Samadhis of Yogi Haridas in the Nineteenth and the Early Twentieth Centuries. Journal of Religion & Society. https://cdr.creighton.edu/bitstreams/handle/10504/151466/2024-15.pdf

Medical note

This series is educational journalism, not personalized medical advice or a protocol for extended fasting. Prolonged fasting can have serious risks, particularly with chronic illness, certain medications, malnutrition or abnormal electrolytes, and warrants professional medical supervision.