Fasting: History and Origins

Fasting is one of the few health practices with no inventor at all. Going without food for a set time is older than writing, older than medicine, older than any named tradition — it grew up independently among hunters who ate when there was food, among priests and prophets who fasted to draw near to the sacred, and among physicians who noticed that sick animals and sick people often stop eating on their own. This article traces what the record actually supports: fasting's deep roots in religion, its place in ancient Greek medicine, the colourful nineteenth-century revival that produced the first "fasting doctors," a genuinely dark chapter that should never be forgotten, and the modern laboratory era — including a Nobel Prize — that finally began to test the old claims. Throughout, we keep two things separate: the long, real history of using fasting, and the much shorter, still-unfinished history of proving what it does. A practice this ancient is a reason to investigate, not proof that it works.

Table of Contents

  1. A Practice With No Founder
  2. Fasting in the World's Religions
  3. Hippocrates and the Greek Physicians
  4. The Nineteenth-Century Revival: Tanner and Dewey
  5. A Dark Chapter: Linda Hazzard and Starvation Heights
  6. The Twentieth Century: Metabolism and the Ketone Switch
  7. The Autophagy Era and a Nobel Prize
  8. The Modern Revival: 16:8, 5:2, and the Researchers
  9. Evidence and Reception Today
  10. Research Papers and References
  11. Connections
  12. Featured Videos

A Practice With No Founder

Many remedies have a name attached to them — a physician, a chemist, a prophet who first put the idea forward. Fasting has none. It is not an invention but a human universal, and any honest history has to begin by saying so plainly: no single person discovered or created fasting, and anyone who claims a sole founder for it is mistaken. The practice arose many times, in many places, for reasons that had nothing to do with one another.

The deepest root is simply biology. For almost all of human history food was uncertain, and the body that survived was the one that could function well through stretches without eating. Long, regular intervals without food were therefore not a health programme but the ordinary human condition — the three-meals-a-day, snack-at-midnight pattern of the modern world is the historical novelty, not the fast. On top of that biological baseline, three distinct streams of deliberate fasting grew up: the religious, where abstaining from food was an act of devotion, mourning, or purification; the medical, where physicians used or recommended it for the sick; and, much later, the scientific, where researchers asked what actually happens in the body when a person stops eating. The sections that follow take each stream in turn, and are careful to mark where firm history ends and folklore or unproven claim begins.

Back to Table of Contents

Fasting in the World's Religions

The oldest documented fasting is religious, and it is found across essentially every major tradition — one of the strongest signs of how universal the practice is. In Judaism, the best-known fast is Yom Kippur, the Day of Atonement, on which observant Jews abstain from food and drink for about twenty-five hours as an act of repentance; the practice is rooted in the Hebrew Bible and is many centuries old. In Islam, the month of Ramadan — a dawn-to-sunset fast observed by Muslims worldwide — is one of the Five Pillars of the faith. According to Islamic tradition, the first Ramadan was observed in 624 CE, the year after the Prophet Muhammad's migration from Mecca to Medina.

In Christianity, the season of Lent — the roughly forty days of fasting and self-denial before Easter — is traditionally understood as echoing the account in the Gospels of Jesus fasting for forty days in the wilderness. In Buddhism, fasting and ascetic discipline figure in the life of the Buddha, Siddhartha Gautama, and many monastic communities continue the practice of not eating after midday. In Hinduism, fasting (upavasa) is commonly tied to particular days, festivals, and deities, and is understood as a discipline of the body in service of the mind and spirit.

What unites these traditions is not a shared origin — they developed separately — but a shared intuition: that voluntarily setting food aside sharpens attention, expresses devotion or grief, and creates a sense of purification. These are spiritual and cultural aims, and this page reports them as such. They are not medical claims, and the religious history of fasting tells us nothing, by itself, about its effects on disease. What it does establish, beyond any doubt, is that disciplined fasting has been part of human life for thousands of years.

Back to Table of Contents

Hippocrates and the Greek Physicians

The medical stream of fasting's history runs back at least to ancient Greece in the fifth century BCE. The physician Hippocrates of Kos — the figure later traditions called the father of Western medicine — is associated with the use of dietary restriction in illness, and several aphorisms about feeding and fasting the sick are attributed to him and the Hippocratic writers. The often-quoted line that "to eat when you are sick is to feed your sickness" is widely passed down in his name; like much attributed to Hippocrates it is best treated as part of the Hippocratic tradition rather than a verbatim quotation we can pin to a single text, and this page presents it that way.

The underlying observation, however, is real and was genuinely made in antiquity. Greek physicians noticed that sick people and animals frequently lose their appetite, and some concluded that this "fasting instinct" was part of how the body recovers — that forcing food on a feverish patient could do harm. The Greeks also recorded a striking clinical fact that modern medicine would eventually confirm: in people with epilepsy, periods of fasting could make seizures less frequent. That single observation, carried down the centuries, is part of the lineage that led in the twentieth century to the ketogenic diet for epilepsy — one of the few places where an ancient fasting observation became established, evidence-based medicine.

Beyond the physicians, Greek philosophers wove fasting into their teaching. Pythagoras is reported to have required periods of abstinence from his followers as a discipline of body and mind, and figures such as Plato are traditionally described as valuing fasting for mental clarity. These philosophical endorsements are part of the cultural record; they are not clinical evidence, and we name them as tradition.

Back to Table of Contents

The Nineteenth-Century Revival: Tanner and Dewey

Fasting re-entered Western public attention in a dramatic way in the late nineteenth century, in the United States, through a handful of vivid figures. The most famous spectacle belonged to Dr. Henry S. Tanner, an American physician who in 1880 undertook a widely publicised forty-day fast — the central event a forty-day public fast he began that summer in New York City — to prove that a person could survive long periods without food and to promote fasting as a treatment for disease. The fast became a national sensation, followed in the newspapers day by day, and it did more than any argument to plant the idea of prolonged therapeutic fasting in the popular mind. Tanner's feat was a demonstration, not a controlled experiment, and it proved survival, not benefit — but it made fasting a topic people argued about.

The more influential medical advocate was Dr. Edward Hooker Dewey (1837–1904), an American physician who earned his medical degree from the University of Michigan in 1864. Dewey became the best-known proponent of what he called the "No-Breakfast Plan" — the idea that people should skip breakfast and eat only two meals a day — and a champion of the "fasting cure" for illness. He set out his views in books including The True Science of Living (1895) and the popular The No-Breakfast Plan and the Fasting Cure (1900), and he attributed a great many ailments to simple overeating. With the benefit of hindsight, Dewey is a genuinely interesting ancestor of the modern time-restricted eating movement: his "skip breakfast, eat in a shorter window" prescription is remarkably close to the 16:8 pattern popular today.

Honesty requires the rest of the picture, though. Dewey's sweeping claim that overeating was the root of nearly all disease was an overreach, and the medical establishment of his day rejected it — the British Medical Journal, for instance, dismissed his cure-all reasoning. These men sat within the broader American "Natural Hygiene" movement, a nineteenth-century school that emphasised fasting, plain diet, fresh air, and water in place of the harsh drugs of the era. Natural Hygiene kept therapeutic fasting alive and popular for a century, and some of its instincts — less overeating, simpler food — have aged well; but its grander claim, that fasting could cure almost anything, was never demonstrated and should not be repeated as fact.

Back to Table of Contents

A Dark Chapter: Linda Hazzard and Starvation Heights

No honest history of fasting can leave out its most disturbing episode, because it is exactly the kind of cautionary truth this practice's enthusiasts tend to skip. In the early twentieth century, Linda Burfield Hazzard (1867–1938) operated a sanitarium near Olalla, Washington, where she treated patients with extreme, prolonged fasting. She had little formal medical training but was licensed in Washington State as a "fasting specialist" under a provision that exempted alternative practitioners. Her facility was officially called Wilderness Heights; locals, with grim accuracy, called it "Starvation Heights."

Patients on Hazzard's regimen were kept on near-total fasts — sometimes little more than broth — for weeks, and a number of them died of starvation. In 1911 she was convicted of manslaughter in the death of a patient and imprisoned. The episode is among the most notorious in the history of unregulated alternative medicine. In a final, grim irony, Hazzard herself is reported to have died in 1938 while attempting one of her own fasting cures.

The point of including this is not to indict fasting itself — brief, sensible fasting is something billions of people do safely — but to be truthful about a real danger: extended fasting without medical supervision can kill, and has killed. Prolonged or repeated fasts carry genuine risks — dangerous electrolyte shifts, refeeding syndrome, loss of muscle, harm to people who are pregnant, underweight, diabetic, or living with an eating disorder. The Hazzard case is the historical reason that "water fasts of several days should be done only under medical supervision" is not a throwaway disclaimer but a lesson written in real lives.

Back to Table of Contents

The Twentieth Century: Metabolism and the Ketone Switch

While the popular movement made its noise, the twentieth century quietly did something more lasting: it began to work out, in real physiological detail, what actually happens inside a fasting body. Researchers traced the orderly sequence of metabolic stages — how, after the last meal, the body first burns through its stored sugar (glycogen), then turns to breaking down fat, and within a day or two begins producing ketone bodies that the brain and other tissues can burn in place of glucose. This shift, from running mainly on glucose to running substantially on fat-derived ketones, is the change modern writers call the "metabolic switch," and it is the firm biochemical core beneath the older language of "the body cleansing itself."

This was also the century in which the ancient Greek observation about epilepsy was vindicated. In the 1920s, clinicians at institutions including the Mayo Clinic developed the ketogenic diet — a very-high-fat, very-low-carbohydrate diet that mimics the metabolic state of fasting — as a treatment for hard-to-control epilepsy in children. The ketogenic diet remains a recognised, evidence-based medical therapy for certain seizure disorders to this day. It is one of the clearest cases in this whole story of a fasting-related insight maturing into mainstream medicine, and it is worth separating sharply from the broader, less-proven claims made for fasting in general.

The same metabolic research mapped the hormonal side of fasting: the steep fall in insulin, the rise in growth hormone, and the release of norepinephrine that keeps metabolism from simply shutting down. These findings, accumulated across the mid-twentieth century, turned fasting from a matter of belief into a measurable physiological state — the necessary groundwork for the explosion of clinical research that came later.

Back to Table of Contents

The Autophagy Era and a Nobel Prize

The single most important scientific development behind the modern interest in fasting is the study of autophagy — from the Greek for "self-eating," the housekeeping process by which a cell breaks down and recycles its own worn-out parts. The decisive figure here is the Japanese cell biologist Yoshinori Ohsumi. In a landmark study published in 1993, working with baker's yeast, Ohsumi identified a set of genes essential for autophagy, and in the years that followed he and others worked out the machinery in detail and showed that the same genes operate in human cells.

For this body of work, Ohsumi was awarded the 2016 Nobel Prize in Physiology or Medicine, "for his discoveries of mechanisms for autophagy." It is essential to be precise about what the prize was and was not for. Ohsumi won the Nobel for explaining how the autophagy process works at the molecular level — not for studying fasting, and not for any claim that fasting cures disease. Misrepresenting his Nobel as a prize "for fasting" is one of the most common errors in popular health writing, and this page does not repeat it.

The connection to fasting is nonetheless real and important. Because nutrient scarcity is one of the signals that switches autophagy on, the discovery of the autophagy machinery gave researchers a concrete, molecular reason to think that periods without food might promote cellular "clean-up" and repair. That mechanistic plausibility — a named, Nobel-recognised cellular process that fasting plausibly engages — is much of what lifted intermittent fasting from a wellness fad toward a serious scientific question. What remains genuinely open is how much, and what kind, of fasting meaningfully changes autophagy in living humans, and whether that translates into the health and longevity benefits often claimed. The mechanism is established; the human payoff is still being measured.

Back to Table of Contents

The Modern Revival: 16:8, 5:2, and the Researchers

The fasting most people mean today — structured intermittent fasting — is a development of the last few decades, and unlike the old fasting cures it grew up alongside actual research. Two formats did most to popularise it. The 5:2 diet — eating normally five days a week and sharply restricting calories on two — was brought to a wide audience in the United Kingdom in the early 2010s, drawing on intermittent-fasting research and turning it into a mainstream phenomenon. Time-restricted eating, most familiar as the 16:8 pattern (a daily eating window of about eight hours), became the everyday face of the movement — and, as noted above, is a close descendant of Edward Dewey's century-old "No-Breakfast Plan."

Several scientists shaped the modern evidence base and deserve to be named accurately. Mark P. Mattson, a neuroscientist long associated with the U.S. National Institute on Aging and Johns Hopkins University, spent decades studying intermittent fasting and energy restriction, particularly their effects on the brain and on aging. Valter Longo, director of the Longevity Institute at the University of Southern California, developed the research on prolonged fasting and the lower-calorie "fasting-mimicking diet," including influential studies on fasting and immune-cell renewal. In 2019, Mattson and Rafael de Cabo published a widely read review in the New England Journal of Medicine that gathered the metabolic-switch framework and the clinical evidence into one authoritative summary — a marker of how far intermittent fasting had travelled from the fringe toward the medical mainstream.

These researchers are pioneers of the modern science of fasting, not founders of the practice. Their role was to take a habit as old as humanity and finally subject it to controlled testing — and, importantly, to be candid that the results are mixed. The detailed mechanisms, protocols, dosing of fasting windows, and cautions are covered on the main Fasting page and across the Fasting Benefits articles; this history is concerned with how fasting came to be studied at all.

Back to Table of Contents

Evidence and Reception Today

Because this is a site that values truth over enthusiasm, the history has to end with an honest account of where the evidence actually stands — and it is more measured than the headlines suggest. The fairest summary from current research is this: intermittent fasting is a legitimate, generally safe approach to eating for many healthy adults, and it works mainly because it helps people eat less — not because the clock itself has magic in it.

On weight and metabolic health, the most important finding is a deflating one for fasting's strongest advocates. When intermittent fasting is compared head-to-head against ordinary daily calorie restriction in controlled trials, the two come out roughly equal. A landmark one-year randomized trial led by John Trepanowski and Krista Varady, published in JAMA Internal Medicine in 2017, found that alternate-day fasting produced weight loss no better than simple daily calorie cutting, and was somewhat harder for people to stick to. More recent systematic reviews and meta-analyses reach the same broad conclusion: fasting-based diets may show a small edge on the scale in the short term, but the difference is not clinically meaningful, and both approaches succeed or fail mostly on whether a person can sustain them. The honest takeaway is that fasting is one valid tool among several, valuable largely for the people who find a fasting schedule easier to live with than counting calories every day — not a uniquely powerful intervention.

The more speculative claims — that intermittent fasting dramatically extends human lifespan, reverses disease through autophagy, or regenerates the immune system — rest mainly on animal studies, short human trials, and mechanism, not on long-term outcome data in people. They are promising and actively researched, but not proven, and should be described that way. Mainstream bodies generally regard intermittent fasting as a reasonable option for healthy adults while cautioning that it is not for everyone. It is explicitly not advised for people who are pregnant or breastfeeding, children and teenagers, anyone with a history of eating disorders, people with type 1 diabetes, and those who are underweight; and anyone on medication — especially for diabetes or blood pressure — should involve a clinician before fasting. Extended multi-day water fasts, as the Hazzard chapter makes unforgettable, belong under medical supervision. Knowing the full history — the wisdom and the warnings together — is exactly what lets a person use fasting sensibly.

Back to Table of Contents

Research Papers and References

The list below combines key peer-reviewed papers with curated PubMed topic-search links into the historical, metabolic, and clinical literature on fasting. Historical figures and primary sources — the Hippocratic tradition, the nineteenth-century Natural Hygiene authors, and the Linda Hazzard case — are named in the article as historical sources rather than as modern citations. Author names, titles, and journals are given as plain text; only the stable DOI, PMID, or official archive link is hyperlinked, and each opens in a new tab.

  1. de Cabo R, Mattson MP. Effects of intermittent fasting on health, aging, and disease. New England Journal of Medicine. 2019;381(26):2541-2551. — doi:10.1056/NEJMra1905136 · PMID: 31881139
  2. Longo VD, Mattson MP. Fasting: molecular mechanisms and clinical applications. Cell Metabolism. 2014;19(2):181-192. — doi:10.1016/j.cmet.2013.12.008 · PMID: 24440038
  3. Trepanowski JF, Kroeger CM, Barnosky A, et al. Effect of alternate-day fasting on weight loss, weight maintenance, and cardioprotection among metabolically healthy obese adults: a randomized clinical trial. JAMA Internal Medicine. 2017;177(7):930-938. — doi:10.1001/jamainternmed.2017.0936 · PMID: 28459931
  4. Cheng CW, Adams GB, Perin L, et al. Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell Stem Cell. 2014;14(6):810-823. — doi:10.1016/j.stem.2014.04.014 · PMID: 24905167
  5. The Nobel Prize in Physiology or Medicine 2016 — Yoshinori Ohsumi, "for his discoveries of mechanisms for autophagy." The Nobel Foundation. — NobelPrize.org: Medicine 2016
  6. Patterson RE, Sears DD. Metabolic effects of intermittent fasting. Annual Review of Nutrition. 2017;37:371-393. — doi:10.1146/annurev-nutr-071816-064634 · PMID: 28715993
  7. Fasting — history and therapeutic use — PubMed: fasting history and therapeutic use
  8. Intermittent fasting versus continuous calorie restriction — clinical trials — PubMed: intermittent fasting versus calorie restriction

External Authoritative Resources

Back to Table of Contents

Connections

Back to Table of Contents