When Did Intermittent Fasting First Appear?

December 21, 2025 •

2 min read

The practice of fasting has been around for thousands of years, long before it became a popular modern diet trend. While today's intermittent fasting (IF) is often used for weight loss and metabolic health, its origins are far more ancient and deeply intertwined with human survival, medicine, and spiritual devotion across countless civilizations.

Quick Summary

Intermittent fasting is an age-old practice originating from ancestral human feeding cycles and ancient religious rituals for spiritual purification and discipline. It has evolved through ancient medicine and 20th-century scientific research before becoming a popular wellness and weight management trend in recent decades.

Key Points

Ancestral Roots: Before agriculture, human beings naturally practiced periods of intermittent fasting out of necessity due to inconsistent food availability.
Religious Origins: Around 1,500 BC, fasting became a deliberate spiritual and religious practice in many cultures and faiths, including the Vedic, Hindu, and Jain traditions.
Ancient Medicine: The Greek physician Hippocrates recommended fasting in the 5th century BCE to aid healing from illnesses, recognizing the body's natural ability to repair itself.
Scientific Re-emergence: Modern scientific interest began in the early 1900s with studies on calorie restriction in animals, and intensified in the 1960s with research on alternate-day fasting in humans.
Modern Popularization: Intermittent fasting became a widespread modern health trend following Dr. Michael Mosley's 2012 documentary on the 5:2 diet, which sparked significant public interest.
Varied Motivations: The purpose of fasting has changed over time from survival and spiritual purification to modern goals like weight loss, metabolic health, and mental clarity.

From Involuntary Fasting to Ancient Tradition

Before the agricultural revolution around 10,000 BC, humans existed as hunter-gatherers, experiencing involuntary intermittent fasting as a natural part of life due to inconsistent food availability. These periods without food helped shape human physiology. Around 1,500 BC, fasting became a voluntary, ritualistic practice rooted in religion and spirituality in traditions like the Vedic, Hindu, and Jainism.

Fasting in Early Medicine and Spiritual Practices

The Greek physician Hippocrates, in the fifth century BCE, recommended fasting for patients to aid healing, believing it allowed the body's natural healing forces to work. Ancient Greek athletes also used fasting to improve performance. Fasting is a cornerstone of many major religions, with varying durations and purposes:

Judaism: Includes the annual 25-hour fast for Yom Kippur and other fast days.
Christianity: Observes the 40-day Lenten fast and specific days like Ash Wednesday.
Islam: Requires fasting from dawn to dusk during the month of Ramadan.
Buddhism: Monks traditionally fast after their midday meal for meditation.
Jainism: Includes varied fasting practices, sometimes involving only water.

The Re-emergence of Fasting in Modern Science

Despite being less emphasized in 20th-century medicine, scientific interest in fasting resurfaced:

Early 1900s: Studies on caloric restriction in animals hinted at lifespan extension, and Upton Sinclair's book The Fasting Cure generated public interest.
Mid-20th Century: Research included studies on fasting for epilepsy and alternate-day fasting protocols.
2000s and beyond: A surge in research explored specific IF methods like 16:8 and the 5:2 diet, linking them to benefits like weight loss and metabolic health.

The Popularization and Commercialization of IF

Media played a key role in bringing IF to the public. Dr. Michael Mosley's 2012 BBC documentary on the 5:2 diet was particularly influential in the UK and Australia. This helped propel IF into a major trend globally. By 2018, it was a leading diet in the United States. Celebrity endorsements and social media further boosted its popularity, leading to commercial products and services.

Comparison: Ancient Necessity vs. Modern Trend


Feature	Ancient Fasting (Hunter-Gatherer)	Ancient Fasting (Religious)	Modern Intermittent Fasting
Primary Motivation	Survival due to food scarcity	Spiritual purification, penance, discipline	Health benefits, weight loss, metabolic health
Intentionality	Involuntary, dictated by environment	Voluntary and ritualistic	Voluntary and scientifically structured
Flexibility	Highly unpredictable	Structured by religious calendars	Highly customizable (e.g., 16:8, 5:2)
Frequency	Irregular, unpredictable periods	Set periods (e.g., Lent, Ramadan)	Regular, scheduled periods (daily or weekly)
Social Context	Community-based survival	Communal religious observance	Individualized or social media trend

Conclusion: A Practice Rooted in History

Asking when did intermittent fasting first appear? reveals a history stretching from the involuntary fasting of prehistoric hunter-gatherers, adapted to survival, to a deliberate spiritual practice in ancient cultures. The modern form is driven by scientific research and popularized for health benefits. This evolution highlights fasting's enduring role, adapting from necessity to spirituality to a contemporary health trend.

This article is for informational purposes only and does not constitute medical advice. Consult with a healthcare provider before starting any new diet or health regimen.

Frequently Asked Questions

The earliest documented instances of intentional fasting appear around 1,500 BC within religious traditions such as the Vedic, Hindu, and Jain religions.

No, hunter-gatherers did not practice intermittent fasting deliberately in the modern sense. Their fasting was involuntary, determined by the natural cycles of food scarcity and abundance.

Greek physician Hippocrates, in the 5th century BCE, was a proponent of fasting for therapeutic reasons, prescribing it to help the body heal from various illnesses.

Many religious fasting practices, such as Ramadan in Islam or Lent in Christianity, can be considered forms of intermittent or periodic fasting, though their primary purpose is spiritual rather than therapeutic.

Modern scientific interest began in the early 1900s, with a renewed focus in the mid-20th century on alternate-day fasting, and a surge in research since the 2000s.

Intermittent fasting was significantly popularized as a mainstream diet trend in 2012 by journalist Dr. Michael Mosley in the UK, particularly his promotion of the 5:2 diet.

The motivation for fasting has shifted from survival and spiritual observance in ancient times to modern goals centered on health optimization, weight management, and longevity based on scientific findings.