desert sunset bahrain
play on top of rocky desert cliffs in Sakhir, Bahrain, at sunset
Friday, March 6, 2009.

AP Photo/Hasan

For his breakfast on July 11, 1966, 27-year-old Scotsman Angus
Barbieri ate a boiled egg, a slice of bread with butter, and a
cup of black coffee. It was the first food he'd eaten in 382

According to a report
published in the Chicago Tribune
, the next day he told a
reporter, "I thoroly [sic] enjoyed my egg and I feel very full."

Barbieri had walked into the University Department of Medicine at
the Royal Infirmary of Dundee, Scotland, more than a year before,
seeking treatment for his excessive weight. At the time he
weighed 456 pounds, "grossly obese," according to a case report

published by his doctors
in the Postgraduate Medical Journal
in 1973.

They planned to put him on a short fast, to try to drop some
weight off his 6-foot frame, but really, doctors expected that
he'd probably lose some fat and regain it, as usually happens.

But as days without food turned into weeks, Barbieri felt eager
to continue the program. Absurd and risky as his goal sounded —
fasts over 40 days were considered dangerous — he wanted to reach
his "ideal weight," 180 pounds. So he kept going. In what was a
surprise to his doctors, he lived his daily life mostly from home
during the fast, coming into the hospital for frequent checkups
and overnight stays. Regular blood-sugar tests assured doctors
that he really wasn't eating and demonstrated that he was
somehow able to function while very hypoglycemic. Weeks turned
into months.

"This is one of the most remarkable cases of voluntary weight
reduction I have ever heard of," one of his doctors told a

Barbieri took vitamins on various occasions throughout the fast,
including potassium and sodium supplements. He was allowed to
drink coffee, tea, and sparkling water, all of which are
naturally calorie-free. He said there was the occasional time
that he'd have a touch of sugar or milk in tea, especially in his
final few weeks of fasting.

At the end of his ordeal, Barbieri tipped the scales at 180.

"I have forgotten what food tastes like," he said before his
long-awaited breakfast. Five years after that, he had kept the
vast majority of the 276 pounds he'd lost off, weighing in at

Transformation through deprivation is an ancient concept. Jesus
was known for spending 40 days in the desert without food. Gandhi
was renowned for
his 17 hunger strikes
, starving himself for up to 21 days at
a time in nonviolent protest. Spiritual seekers around the world
atone for sin and seek enlightenment through periods of fasting.

Yet Barbieri's fast is believed to be among the longest ever
undertaken, and it was done not for spiritual salvation but for
physical health.

Screenshot 2016 09 23 09.35.21
Tribune Archive

This feat has made Barbieri a legend among people who voluntarily
choose to fast to transform their bodies, and to fight obesity
and pain and disease.

People seem to be more interested than ever in fasting to
transform themselves. Silicon Valley
startups fast together
for productivity and
books touting recently developed intermittent
remain top sellers
even a few years after being
published. The number of
research papers
published mentioning fasting has steadily
grown, year after
, from 934 in 1980 to more than 5,500 in 2015.

And thanks to the internet, tips, encouragement, and advice are
more accessible than ever. It's always easier to do something
"extreme" when others around you are telling you that it's not so
crazy after all, that many people have done it.

Yet despite the long history of fasting, giving up food is not
necessarily a good idea. While short fasts are generally
considered safe, longer fasts could introduce dangerous health
risks, especially for people without the body fat to support
those efforts. As a means of restoring health, fasting is a
luxury for those who can take supplemental nutrients and don't
struggle with hunger and malnutrition. It's hard to separate "not
eating" for health from potentially deadly eating disorders.
Without medical supervision, a temporary fast for health could
transition into a dangerous disorder.

But still, radical transformation is a powerful draw.

Starving for health and long life

Fasting is having a moment right now. At a time when researchers
are doing everything they can to battle aging and the chronic
diseases of the body and brain that come with it, many of the
most promising interventions have some connection to this ancient
and — when compared to modern pharmacy — simple practice.

Today's fasters aren't necessarily looking for salvation, but
they still want to be healed.

We think of food as comfort and sustenance. It's the thing we
gather around for celebrations of birth and even occasions of
grief. And sure, we know it's possible to eat too much, we know
that a growing number of people around the globe struggle with
obesity and associated illnesses, but that's a specific case of
overdoing it.

We always want to keep eating, right? Isn't that what we are
supposed to do?

Maybe not.

gandhiAP/James A. Mills

What we mean specifically when we say "fasting" varies

We could be talking something like Ramadan, during which people
fast from dawn to sunset, or we could be describing a longer
period when people consume only water. Some cut food intake a few
days a week; others talk about drastically reducing daily
calories. Depending on the researcher, alternative-health clinic,
or helpful internet stranger you reach out to, you'll hear
different ideas about what you should be doing and why you should
be doing it.

But the basic idea is simple. You stop eating.

It goes against what we're told growing up and what seems to be a
natural survival instinct. People who work with patients
suffering from eating disorders say extreme diets easily turn
into food obsessions, disordered eating, and dangerous behavior.
After an extended time without food, a person's heart starts to
suffer. Someone with enough body fat can survive off that fat for
a while, but eventually it will run out, with potentially deadly

Yet there are reasons to think fasting advocates might in some
way be right. Maybe we aren't supposed to have easy access to
food at any and all times. Maybe, as some
does show, periods of fasting might wipe away the
physical changes making us more obese and diabetic. Maybe these
periods of hunger might help fight cancer, by starving and
killing rapidly growing tumor cells, as some preliminary
seem to indicate. Maybe drastically reducing what we
eat can actually help slow aging and stop the process of decline
that causes our bodies to become decrepit and shaky over time. It
works in
some animals

There's promising data out there. And yet there are still a
number of lingering questions.

After talking to researchers, doctors, people who run clinics,
and people who have decided to just stop eating for a period, we
know that the promise of radical transformation might be a true
one that taps into a deep and perhaps necessary part of our
nature. But we also know that if it goes wrong, a fast can kill.

The hottest intervention for fighting disease, aging, and other
health problems has roots in a prehistoric survival mechanism

Picture a group of early humans journeying through what we would
now call northern Europe, looking for safe new lands. Perhaps
they were driven from more comfortable territory that they
unsuccessfully tried to take from a group of Neanderthals, or
perhaps they fled another group of warfaring Homo sapiens. Maybe
there were reasons to think the hunting would get better if they
stayed on the move.

homo jawBrian Villmoare

Our traveling band may have been relatively comfortable during
the spring and summer months through which they'd traveled, but
now winter is coming to these new northern lands. It's cold. Food
has become scarcer. Throughout the next months, they'll be able
to find and kill just enough to make "full meals" every so often.
They'll often have to survive weeks between those times.

This story represents what was normal for humans all over the
world for thousands of years. Yet humanity managed to survive,
thrive, and spread.

That ability to fast is an ancient survival adaptation, according
to Leonard
, the Novartis Professor of Biology at the Glenn
Laboratory for the Science of Aging at MIT. As he told Business
Insider, when we came across those times of cold when food was
scarce, the natural processes in our bodies would slow.

Women became less fertile, as a time of famine is no time for a
child. Aging itself would slow, giving us a chance to live past
the hard times. Then when fortunes reversed, when our traveling
band lived through the long winter and spring arrived, with life
blooming and food plentiful, we'd grow again, we'd eat and
reproduce — but also age.

That concept of fasting as an ancient mechanism that delayed
aging is what makes serious researchers who are trying to figure
out how to slow the diseases that come with growing old so
interested in the biological changes that occur in our body when
we stop eating.

This also explains why fasting may have some of the benefits for
our bodies that the converted preach. After all, being
hungry isn't lifeless or drained; it's actually when our
bodies and brains need to function at maximum capacity. In a
sense, some of the truth of this is built into our language. We
use words such as hungry to describe someone who is
driven and eagerly pursuing a goal.

"Think of a predator that has to find, track down, and chase prey
in a setting where the prey are limited in numbers," says
, chief of the laboratory of neurosciences at the
National Institute on Aging at the National Institutes of Health.
"Those predators often have to go several days, many days, even
longer without eating.

cave paintings in lascaux France

"It makes sense that the brain needs to be functioning very well
when an individual is in a fasted state because it's in that
state that they have to figure out how to find food … they also
have to be able to expend a lot of energy. Individuals whose
brains were not functioning well while fasting would not be able
to compete and thrive."

So it makes sense that fasting helped us live through the cycles
of starvation and of plenty. It's not crazy to say that perhaps
we evolved to live with some sort of natural schedule that
alternates between being able to eat and having nothing at all.

If the antiaging researchers and dietary advocates are right,
maybe we in some way need this, maybe fasting can help fight
Alzheimer's, cancer, and arthritis, all while helping our bodies
regulate blood sugar properly for the first time in years.

But let's not go too far here. There's evidence that fasting
may help with a laundry list of diseases, but in the
vast majority of cases, careful experiments have not yet
demonstrated that fasting can cure disease or slow aging. If
there were such evidence, we'd all do it already. Fasting is
promising, but promising is not proven. 

It's understandable if the almost evangelical fervor that
sometimes surrounds fasting provokes skepticism as well as

So is fasting dangerous?

Obviously humans need food. People who try to
survive on just light and air die

Linda Hazzard serial killer
State Archives

And while there are stories like Barbieri's that make fasting
almost sound safe and transformative, those who worry that
fasting proponents sound like dangerous snake-oil salesmen can
find stories to vindicate their case, too. Take the story of

Linda Hazzard

Hazzard was a practitioner of alternative medicine in Washington
state in the early 1900s. She branded herself a "fasting
specialist" and wrote articles and books with titles such as
"Fasting for the Cure of Disease." She even started her own
fasting clinic, the Institute of Natural Therapeutics in Olalla,

Many considered her a serial killer.

About 50 people reportedly died in Hazzard's care, though she was
convicted of only one murder. "Tales are told of her Sanitarium
in Olalla on the Kitsap Peninsula, where starving patients
stumbled like human skeletons into town, begging for food or
according to a post
on the Washington Secretary of State's
office blog. During their treatments, "patients consumed only
small servings of vegetable broth, their systems 'flushed' with
daily enemas and vigorous massages that nurses said sometimes
sounded more like beatings,"
according to
Smithsonian Magazine. Before their deaths, many
of those patients willed their estates and inheritances to the

Hazzard was eventually found out after the case of Claire and
Dora Williamson. The sisters had enrolled at the center for
treatment, but after some time, one of them sent a disturbing
message that persuaded their childhood nurse to travel from
Australia to Washington to find them. When the nurse arrived,
Claire was dead and Dora weighed about 50 pounds, and Hazzard had
actually been appointed her guardian. The sisters' uncle
eventually paid Hazzard a thousand dollars to get Dora away from
the property. That led to other revelations and, eventually, a
murder trial. Hazzard was convicted of murdering Claire

But for reasons that remain unclear, Hazzard was pardoned after
serving two years. She traveled to New Zealand before returning
to Washington to build a new sanitarium. Eventually, after
falling ill, she tried to cure herself in the way that she knew
and seemed to believe in, by fasting. That last fast killed her.

Hazzard, of course, wasn't just a quack. She appeared to have had
malicious intent.

Under a doctor's supervision, most people can handle a fast of a
certain duration, especially if they take vitamin supplements.
But researchers have found that after about six weeks people
start to enter a danger zone, according to Frank
, chief medical officer at Pennington Biomedical
Research Center at LSU. By seven weeks, electrocardiograms
start to show
heart trouble, and by eight weeks people are at
risk of sudden death, Greenway says. Skinny people might enter
that danger zone sooner.

Even diets that provide food but not adequate nutrition have
killed people in this way. In the late 1970s, Greenway says that
an osteopath named Robert Linn wrote a book called "The
Last Chance Diet
," which promoted a low-calorie, high-protein
solution for weight loss. But the nutritional drink Linn sold was
made with a low-quality protein, which didn't provide what people
need to live. A number of
people on this diet died
, their hearts showing signs of

Namib Desert

Those risks are real, but experts such as Greenway and Mattson do
agree that most people, especially those with some weight to
lose, are fine on longer water fasts lasting several weeks, as
long as they are medically supervised and in reasonable health to
begin with (certain health conditions might be exacerbated by

One of the biggest myths about fasting is that it's dangerous,
says Alan Goldhamer, an osteopathic physician and chiropractor in
California and the founder of TrueNorth Health Center,
where 15,000 patients have undergone periods of water fasting
over the past 32 years.

Barbieri completed his 382-day fast after all, and his isn't the
only fast longer than 100, 200, or 300 days. In 1964, researchers
published a study noting that "prolonged starvation" could be an
effective treatment for severe obesity, with
at least one patient fasting
for 117 days. For medical
several others have exceeded
the 200-day fasting mark, though
there has been at least one death during the refeeding period for
one of those patients. (Suddenly introducing
to a malnourished person can be deadly.) At least
one person has even gone longer without food than Barbieri; a man
named Dennis Galer Goodwin lasted 385
days on a hunger strike
to assert his innocence of a rape
charge before he was force-fed through a tube. But those are
extreme examples. Fasts longer than a few weeks are rare.

Still, Goldhamer says patients at TrueNorth have medical
supervision throughout their fasts. Clinic staff members keep an
eye on people and ensure that they'll be able to give them
electrolytes or broth if they become faint or have a medical

Many people are comfortable enough with fasting that they embark
on long fasts on their own. Chris Guida, one such
self-experimenter I reached out to through Reddit, described how
he decided to start a three-week fast.

Fasting was just one part of a longer effort to improve Guida's
health that started in 2013 and involved various diets and
exercise programs such as CrossFit, he tells Business Insider. At
the time, he was 24 and having back pain. He'd lost the ability
to hear certain treble frequencies in one ear. So he decided he
wanted to try to conduct a self-optimization project, turning
himself into a "science experiment." He tried the paleo diet,
eliminated caffeine, and stopped sitting all day (he'd been
working as an app developer).

Eventually he came to fasting, which seemed like the "logical"
conclusion of his efforts.

"I found tons of helpful resources online that convinced me I
shouldn't have any problems, and once I found r/fasting, I knew I could
turn to that community if I really needed anything," he wrote,
just over one week into his own water-only fast. "It was time."

Sixteen days into his fast, Guida told Business Insider that he
felt good but that, overall, he didn't have a ton of energy. He
said he was cautious because his weight was already pretty low.

Goldhamer said "we tend not to want to go over 40 days unless we
absolutely have to" and that certain patients with severe medical
conditions can be too sick to fast. He still argues that fasting
is safe, but agrees complications are more likely with longer
durations. The Guinness Book of World Records stopped
keeping records
on periods of prolonged starvation at least
in part because they didn't want anyone to die trying to exceed a

The evidence that says fasting can help

elderly aging old man walkingKevin

With tens of thousands of patients, centers like TrueNorth and
the Buchinger Clinic in Germany have helped demonstrate that
fasting itself is safe, says Valter Longo, a
professor of gerontology and biological science and the director
of the University of Southern California Longevity Institute.
That doesn't mean it's risk-free, but at least in a supervised
context, most people are fine. Longo, whose primary interest is
in slowing human aging, has been studying two questions. First,
what exactly is happening in the body when someone fasts? And
second, can we replicate that mechanism without fully cutting out

Longo is fascinated by the biological mechanisms of fasting, and
he's not alone. Many researchers believe that fasting might
kick-start some sort of protective or healing process in the
body. The confusing thing about this "healing mechanism" that
many refer to is that it isn't just one physical characteristic —
fasting seems to have systematic effects, like a reboot for the
body. Researchers think that if there's a way to activate these
biological mechanisms without actually forgoing food for an
extended period, that alone could be enough to transform health.

Published research on fasting and its effects on health is
limited. It's an evidence-backed hunch, not a sure thing. That
doesn't mean it doesn't work. The research may be skimpy simply
because there aren't many people interested in funding a study on

We know fasting can help with weight loss, though there's never a
guarantee people can keep weight off. One recent
study of "The Biggest Loser"
participants raised questions
about whether intense diet and exercise programs might slow
someone's metabolism, but there isn't much data to suggest that
fasting will necessarily do the same, says Greenway. Fasting can
effectively treat hypertension, with some of the
supporting that conducted by Goldhamer of TrueNorth.
Historically, researchers have found ways that fasting seemed to
work for treating certain forms of diabetes and epilepsy. But
frequently, research on using fasting fell out of favor once a
pharmaceutical company developed a medication that could do the
same job. Most people prefer to eat.

As Steve Hendricks wrote in a
2012 Harper's feature
, historical evidence he found suggested
that "starvation, a remedy that cost nothing — indeed, cost less
than nothing, since the starver stopped purchasing food — was
abandoned whenever a costly cure was developed. Decades later,
studies would show that fasting followed by a high-fat diet was
as effective against seizures as many modern anticonvulsants and
that variants of the Allen Diet [a fasting regimen] were
effective against diabetes. But Americans, then as now, preferred
the promise of the pill over a modification of menu."

And you can't patent the absence of food. "One reason that there
hasn't really been a tremendous amount of research is that
there's no money behind it except for government grants," says
Mattson. Drug companies don't have much of a reason to study
fasting. It's not their product. As Mattson points out, there are
more forces out there promoting the consumption of food than not,
with ad campaigns successfully convincing people that eating
breakfast makes them healthier or that drinking a glass of milk
or orange juice every day is necessary, though none of these
things are true.

It's also been hard to show that fasting works in humans. Take
caloric restriction, which is a dietary intervention related to
fasting, though it's not the same since it allows for some
eating, just far less than normal. We have extensive evidence
that caloric restriction can dramatically extend the lives of
certain lab mice and even keep them physically "younger" when
compared to mice allowed to eat whatever they want. But we don't
know that drastically reducing calories in people will do the
same. Not all mice respond in the same way, says Longo, and in
people we think that some of the negative side effects of a
calorie-restricted diet (30% below normal) would outweigh the
health benefits.

"The malnourishment becomes worse than the cancer or Alzheimer's"
that caloric restriction might prevent, says Longo. We really do
need a certain number of calories to survive, even if it might be
good for us to cut back on or eliminate those calories every so
often. If we could get those effects from caloric restriction
without triggering the negative side effects, it would be
remarkable. But that's simply not possible — yet.

fasting ramadan taj majal
attend Eid al-Fitr prayers to mark the end of the holy fasting
month of Ramadan, in Agra, India, in 2016.

REUTERS/Pawan Kumar

That's why researchers are trying a variety of strategies to
isolate the "good parts" of fasting.

Mattson describes how research on a diet that involves fasting
two days a week by consuming just 25% of normal caloric intake on
those days shows that such a diet can
reduce breast-cancer risk
and helps people lose
, and this diet works more effectively than calorie
restriction, though more research on more people is needed.

Still, a
recent review of animal studies
seems to support that idea.
Calorie restriction alone may not be enough to trigger fasting's
healing mechanism. It may be that drastically cutting calories
two days a week is enough to start a healing process, but
restricting calories less severely throughout the week will not
have the same effect.

Other researchers are trying different ways to trigger that

For Guarante, fasting is the
inspiration for a supplement
that he thinks can activate
cellular mechanisms that would stop cells from age-related decay.
He discovered that these
pathways seem to be triggered
by a fasted state. He and his
colleagues hope that the supplement could
repair DNA, restore energy levels, and generally rejuvenate
person. There are a
number of peer-reviewed papers
that provide evidence that
ingredients in this supplement do act on these pathways in the

Still, acting on these pathways and showing these benefits in
cells or small organisms doesn't mean the same thing will happen
in humans. Right now, we don't have any way of showing that
something slows aging itself. These things are hard to prove, and
since this product is being sold as a supplement, Guarante's
company Elysium
does not need to prove to the FDA that it can do these

has a different approach
. He has developed a carefully
calibrated diet that relies on limiting food consumption for five
days a month, something that could be done a few times a year. He
says that diet — a "fasting mimicking" diet, since it's not
fasting itself — could kick-start an internal healing process,
lowering blood sugar, lowering the risks for cancer and
Alzheimer's and diabetes, and improving people's cognitive
ability and physical capacity. Again, more research is needed
here, even if
initial human studies
have had promising results.

BI Graphic_4 types of fastingDragan Radovanovic/Business

Much of this research has been in development for some time, and
now, when both interest in fasting and antiaging seem to have
come together, the world seems to be on the verge of embracing
these approaches.

People such as Goldhamer — more on the fringe than part of the
traditional research establishment — love that people are
starting to believe there really might be something to this whole
fasting thing.

"We've gone from 'criminal quacks' to being cutting-edge
researchers," he says. "It's letting us play with the big boys,"
the pharma companies that have never been interested in a
treatment of deprivation but are intrigued by the possibility of
trying to mimic the effects with a drug.

Many people who've read about this don't want to wait for a
proven pill that mimics the potential benefits of fasting —
they're already true believers in fasting itself.

The people who don't want to wait

It's hard not be tempted to try fasting when you read these
reports of rejuvenated health and transformation through
deprivation. (If you're thinking about it, please consult your
doctor first.)

And there are a lot of people who decide to embark on a
fasting journey on their own. Many of those people gather
information and chat in online communities to share tips and
personal accounts of their experiences.

In some places, like the fasting subreddit, you can frequently
find users discussing
what it feels like to be on a fast
, sharing information about

different types of fasting
, and, in some cases, cautioning

people against unhealthy behavior

Deciding to forgo food is extreme, and doing so doesn't seem like
a safe decision to people such as Ilene Fishman, a social worker
who specializes in eating disorders and helped found the National Eating
Disorders Association

"Somebody who gets involved with fasting is going to end up
moving into disordered eating [and] it's going to become
preoccupying," she says. At the end of World War II, a researcher
named Ancel Keys decided to experiment with long-term low-calorie
diets, something that became known as "The
Great Starvation Experiment
." Study participants struggled
with mental disorders and became obsessed with food, and
returning to normal was not easy or even always possible. There
is a chance that an unsupervised fast could trigger an eating

In online discussions, you can see where the border between
fasting for health crosses into dangerous behavior, with some
users explaining that they're trying to hit a target weight that
is clearly dangerous.

sailboat alone sunset sea ocean solitude lonely old man and the sea

But at the same time, many insist they are just trying to figure
out how to be healthy and that fasting — with its great promise
and long history — is appealing.

Chris Guida told us what it's like to be on his water-only fast.

"This is my longest fast ever, so I have nothing to compare it
with," he wrote just over one week into the fast. "In terms of
well-being, I feel better than normal … there are times when I
feel tired or anxious or hungry, but those feelings are fairly
easy to ignore because of the sense of overall progress I'm
making. My senses feel like they're getting sharper, and my
muscles feel relaxed and delightfully stretchy. My body feels
light and free, rather than cumbersome."

Sixteen days in, Guida told us that he was "still going strong!"

The thing is, no one knows if what Guida is trying to do will
solve his back pain or a hearing issue (though he does say he was
able to do a headstand recently). These ailments could be beyond
the already broad benefits associated with fasting, unless they,
too, are addressed by the same healing mechanism.

And that's not impossible. Fasts have been shown to reduce
inflammation, something researchers have found beneficial
for asthma patients
. Inflammation reduction could help with
back issues. Even a placebo effect can have long-term health

Either way, Guida wanted to do it. Part of that could be an
effort to solve specific issues, but that decision may simply be
faith in fasting itself. Many of the people I spoke with seemed
to feel that the world was ready to start benefitting from
fasting, whether that came through a traditional route or a way
to mimic those effects.

Longo said he'd be surprised if something like the
fasting-mimicking diet wasn't part of the standard of care within
10 years. If so, he says, "I wouldn't be surprised if this could
lead to a 10% longer but a much healthier life span."

Mattson says he thinks insurance companies should start putting
people on one-month "rehab" programs to change their relationship
with food and exercise, which could help them adapt to an
intermittent-fasting program.

Whether fasting actually does transform life in these ways
remains to be seen. But remember, no matter what, if you want to
go the traditional, water-only hard-core fasting route, it's not
going to be easy.

"Fasting is an intense and miserable experience" for most people,
says Goldhamer, who has seen 15,000 people come through his
clinic. "But if we get a good result, they forgive us."