Humans were forced into periods of fasting throughout our evolution due to scarcity of resources, punctuated by brief periods of feasting.  Interestingly, since the more recent development of farming and food refrigeration, humans have continued to fast, often for strange, diverse, and powerful reasons.

You’ve no doubt heard of fasting for religious or cultural reasons, and more recently you’ve probably heard about intermittent fasting and time-restricted eating methods as weight loss tools popularized by celebrities and friends alike.

But the practice of fasting has been around for hundreds of thousands of years. Early humans had to hunt or forage for food after waking up with the sun, so they likely would have inadvertently practiced a “circadian fast” during daylight hours, or perhaps a longer time-restricted eating fast depending on how long it took to acquire food. If no food sources were available, they likely practiced more extended periods of involuntary fasting.

Here, learn more about the curious and fascinating history of fasting from centuries ago and why it’s become popular in modern times. 

Fasting in modern times

In American culture, food is constantly available for many of us.

“Fasting sits neatly at the intersection of powerful trends in American culture: the longstanding celebration of self-mastery and restraint around food, and a newer impulse to ‘optimize’ every aspect of one’s life,” saysNatalia Mehlman Petrzela, Associate Professor of History at The New School, co-host of the Past Present Podcast. “The religious language—’fasting’—also elevates it to a pursuit that feels more noble than calorie counting.

“Our contemporary diet culture is based on the idea that restraining oneself from partaking in an abundance of available food is a virtuous act,” says Petrzela. “As food became cheaper and more widely available with industrialization, resisting highly-caloric food is a way of showing class and status rather than partaking in something now so widely available.” 

“Food insecurity in the U.S. is not only about hunger, but lack of agency over one’s food, whether that’s insufficient resources to buy healthful food, eat regularly, and create wholesome portion-controlled meals,” she says. “Fasting deliberately is less a form of ‘voluntary starvation’ and more a way of demonstrating control over one’s eating and food, which in a food-insecure nation is a privilege, especially when that agency is employed not to eat,” Petrzela says.

It is a privilege to be able to pick and choose when you eat and what you eat when breaking a fast.  Amongst the high-status Americans who openly discuss using intermittent fasting to maintain their figures include the following celebrities: Jennifer Aniston (16:8), Kourtney Kardashian (24-hour fast or 16:8), and Jimmy Kimmel (5:2 diet). “I think intermittent fasting has become more popular lately because of attention from celebrities,” says Krista Varady, Ph.D., is a Professor of Nutrition at the University of Illinois, Chicago, author of The Every Other Day Diet, “People are tiring of really complicated, expensive diets. They want something simple. 

“Part of the appeal of fasting is also getting to eat without restriction during certain hours, so that notion of control over one’s food applies not only to being able to resist but also to choosing to eat with abandon,” says Petrzela. 

The history of fasting for weight loss

While some people practice fasting to cleanse and achieve a spiritual state and this has been a regular practice for hundreds of years, deliberately using fasting and intermittent fasting in order to lose weight is a modern practice. 

“We think interest came out of religious fasting,” says Varady, who studied calorie restriction during her post-doctorate years. “I think, probably the closest thing to time-restricted eating and similar interest in this was Ramadan fasting, where people fast from sunup to sundown. Intermittent fasting is usually the reversal of that practice. 

“I noticed that people really struggled when they were trying to reduce energy intake every day, just because they have to be hypervigilant about monitoring calories,” she says. “I thought, well, do people really have to diet every day to lose weight? Or, can you just undergo kind of heavier periods of restriction? Perhaps just a couple of days a week, you’ll fast and then give yourself a couple of days off in between. We were the first lab to look at whether or not people can use intermittent fasting for weight loss.” They also conducted the first study on alternate day fasting. 

Intermittent fasting (IF) is the umbrella term for many different methods. There’s alternate day fasting (ADF), where people eat 500 calories or less every other day and have normal food consumption every other day (some people do a water fast instead of 500 calories). Then there’s the 5:2 diet, with two 500-calorie days per week and five days of normal calorie intake. “Also, there’s time-restricted eating, which is definitely the most popular form right now,” says Varady. People usually eat during an 8 or 12-hour window and water-fast for the rest of the day (or more typically overnight). 

“The nice thing with restricted eating is that you can follow the diet without needing to change what’s in your pantry,” says Varady. “Time-restricted feeding is probably getting more popular because people find it easier to do. You don’t have to count calories; all you have to do is pick a time window for eight hours if you’re following a 16:8 plant,” says Varady. “Pick the time frame for the day and stick to that. Studies have shown that people naturally eat about 300 to 500 calories less just by watching the clock with this practice.” 

The history of fasting for religious reasons

Muslims practice fasting during the holy month of Ramadan, from sunup to sundown. Catholics fast during Lent on Ash Wednesday, Good Friday, abstain from eating meat on Fridays, and usually give up something throughout the 40 days. While there are six fasting days in the Jewish calendar, the most popular fast is on their holiest day of the year, Yom Kippur, which involves fasting from sundown to sundown in either September or October to observe the “Day of Atonement.”

Fasting in Hinduism is an optional practice believed to purify the body and mind to achieve “pure grace.” Fasts followed by Hindus range from light fasting—perhaps cutting out meat or eliminating one meal a day—to longer-term fasts, which might involve fasting during the day or one day a week. 

The history of fasting for health

Perhaps the most well-known ancient practice of fasting for health was utilized by the ancient Greek physician, Hippocrates. The “father of medicine” lived from 460 B.C. to 375 B.C. and recommended patients abstain from food and drink to cure ailments as it was believed that fasting helped the body recover naturally from illnesses.

Beyond that, better understandings of fasting came about in the 19^th century as studies were conducted on animals and humans. American physician Dr. Edward H. Dewey preached the health benefits of fasting and developed a “no breakfast” approach to health and weight loss in the mid-to-late-1800s. Throughout the 20^thcentury, various fasting methods were used to treat chronic ailments. Some physicians in the early 1900s used fasting to treat epilepsy, diabetes, and obesity. Early methods practiced by doctors involved modified fasting, which included caloric intake of 200 to 500 calories daily (early 5:2 diet, anyone?), or eating only 800 calories a day to induce weight loss. 

Another  early adopter of fasting for health reasons was Paul C. Bragg, N.D., Ph.D., Dr. Bragg used water fasts in the early 1900s to purify the body, rest the digestive organs, improve heart health, and live longer. People believed fasting was just “crazy talk,” but Bragg continued to teach about the healing effects of fasting in his lectures.

Bragg and his daughter, Patricia Bragg, N.D., Ph.D. wrote The Miracle of Fasting: Proven Throughout History for Physical, Mental and Spiritual Rejuvenation, published in 1970. (You might recognize Bragg’s name from Bragg Apple Cider Vinegar, founded by Paul Bragg in 1912.) The Braggs Healthy Lifestyle plan recommends 24-to 36-hour distilled water fasts weekly for longevity and health benefits—and 92-year-old Patricia still practices those fasts! 

Today, quite a few research facilities are dedicated to studying the health benefits of fasting, like the Salk Institute for Biological Studies, whose research team is led by Satchidananda Panda, Ph.D. The Salk Institute lab studies the effects of the circadian clock on the body’s systems and discovered that confining caloric consumption to an 8- to 12-hour period might stave off high cholesterol, diabetes, and obesity.

The history of fasting for longevity

Humans have been studying the “secrets for a longer life” for thousands of years, and science continues to conduct studies on the role diet plays in our lifespan. While it’s a challenge to conduct lifelong studies in humans that follow calorie intake from birth until death, animal models show that calorie restriction—sometimes in the form of intermittent fasting—may lengthen lifespan. 

University of Southern California Professor Valter Longo is known as the “fasting evangelist” and studied the life-prolonging benefits of fasting for decades. Professor Longo is director of the Longevity Institute at the Leonard Davis School of Anti-Aging Medicine and has studied the benefits of fasting on patients receiving chemotherapy and the health effects of following fasting-mimicking diets (FMD). Right now, Professor Longo is working on investigating how the effects of fasting and FMD can help with immune function, in particular, vaccine efficacy and the body’s response to viral infections like influenza and COVID-19, according to the Keck School of Medicine website.

Animal trials at the National Institute on Aging have demonstrated that increasing time between meals improves the overall health of male mice. They live longer than mice that eat more frequently. Researchers are continuing to study the role calorie-restriction and delayed feeding plays in adding years to human lives.

The history of fasting for cleansing and renewal

Embarking on a voluntary ‘spring fast’ is said to be followed by several populations, including the Hunzas in the upper valleys of the Himalayas in North India. It’s said that this period of fasting helps them prepare for a new phase of existence, according to Alimentarium.org. The famous Indian lawyer Mohandas Gandhi used to fast to help free himself of constraints of the body

It’s also said that ancient Greek philosophers fasted to improve intelligence and perception.  Pythagoras supposedly fasted for 40 days before his exams and encouraged his philosophy students to fast in order to sharpen their minds. Other ancient Greeks believed in the practice of fasting to improve cognitive abilities.

The history of fasting for passive resistance

Voluntary fasting has occasionally been taken to the extreme for political reasons in the form of hunger strikes.

Hunger strikes took place in the early 1900s by female Suffragettes in British prisons who threatened to starve themselves as an act of non-violent protest. Some men joined the starvation practice over the years in solidarity. 

The Irish have also been known to embark on hunger strikes to bring attention to injustice, in particular the 1981 hunger strike to end political prisoner statuses for IRA prisoners. Ten male prisoners died during that hunger strike.

It’s said that Gandhi participated in hunger strikes as a method of resistance, to protest against violence between Hindus and Muslims, or to protest the British government’s decision to separate India’s electoral system by caste History.com.

Methods of deprivation, voluntary fasting, or starving have been used by our ancestors across cultures. They will likely continue to be used by generations to come for health benefits, political reasons, and spiritual pursuits.