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Hungry for Health: Fasting's Medical Benefits
John Watson

DISCLOSURES July 12, 2018
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IN THIS ARTICLE
For most of us, a growling stomach is a siren song calling us to our refrigerator. However, for researchers and adherents of intermittent fasting (the practice of voluntarily abstaining from food and nonwater beverages), hunger is something not to vanquish but rather to embrace.

Fasting has been shown for years to be an effective nonpharmacologic strategy for counteracting some of the most entrenched modern ailments, from cardiovascular disease and cancer to diabetes and diminishing cognition.[1] The stumbling block was that this evidence was derived primarily from studies in rats and mice, which meant that intermittent fasting remained an interesting, but somewhat fringe, field of research. That has decidedly changed, though, with the recent publication of some small but promising investigations showing positive outcomes in humans.

"In the early 1990s, my own science colleagues viewed fasting as irrelevant, and it was largely ignored by the medical community," explained Valter Longo, PhD, a forerunner of fasting research and director of the Longevity Institute at the University of Southern California, Los Angeles. "Now things are changing very rapidly, and fasting is the most widely adopted diet in those under age 34 in the United States."

Fasting is the most widely adopted diet in those under age 34 in the United States.
Intermittent Fasting's Various Forms
"Intermittent fasting" is an admittedly vague umbrella term but one that is nonetheless useful for describing a wide variety of regimens.

The most popular fasting regimen is undoubtedly the 5:2 diet, in which participants restrict themselves to approximately 500-600 calories 2 days a week but eat as they normally would for the remaining 5 days. It comes garnished with all-important celebrity endorsements (for example, Jimmy Kimmel and Benedict Cumberbatch) and glossy coverage in magazines you would find at any grocery store checkout lane.

Other common regimens include time-restricted feeding (eat a standard amount of calories, but only within a limited time frame), alternate-day fasting (eating nothing one day, then whatever you like the next), and periodic fasting (abstaining from food and energy-containing beverages for continuous days, sometimes stretching out to 3 weeks). In addition, researchers such as Longo are investigating the efficacy of fasting-mimicking diets for reducing markers of aging and risks for age-related diseases.[2]

Because there have been no large randomized controlled trials comparing these regimens, we cannot yet establish superiority for any. Trends uncovered in clinical studies suggest some with greater potential though, according to Longo.

"I think the clinical evidence is strongest for the periodic fasting and fasting-mimicking diets used to treat specific problems, including obesity, high cholesterol, high blood pressure, inflammation (C-reactive protein), high triglycerides, and high fasting glucose/metabolic syndrome," he said. "The other major advantage of a periodic fasting or fasting-mimicking diet is that it only needs to be done for most people three to four times per year for 5 days."

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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this article: Hungry for Health: Fasting's Medical Benefits - Medscape - Jul 12, 2018.

Introduction
Why Fasting May Work
The Fasting Brain
The Future of Fasting
References
Comments (47)
Dr. mohaamed aleem

Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Dr. K S|  Pediatrics, Allergy 6 minutes ago
I think it is a excellent way to loose weight I see the program Neked in the wild program I saw people who participate in this game to survive in wild cannot find food for days and then kill a animal and eat I saw all of those people loosing weight and still active and normal we should do research on these people Dr Singh Sarnia Ont

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Dr. ALEJANDRO JIMENEZ|  Pediatrics, General 55 minutes ago
I find it interesting, but I would like to have more information on the subject.

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Dr. Uzo Ezegwui|  Ob/Gyn & Women's Health 1 hour ago
well thought  article.It seems humans are designed  to have period of fasting. Fasting is included in many religious activities. I read Jesus fasted 40 days and forty nights. They may be  more to fasting that we currently know in the scientific world.

Randomised control trial is  urgent.

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Dr. AMELIA HARE|  Ob/Gyn & Women's Health 3 hours ago
Humans [and other species] have of necessity not infrequently experienced episodes of food shortage or even periods of a complete lack of food though their evolutionary development.  Accordingly, by and large we have evolved from a background of episodes of limited food and continuing in this way despite having the opportunity for a continuous food supply may enable a longer life.

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Dr. Richard Cooper|  Ophthalmology 3 hours ago
Excellent article, thank you.  Recently we discovered "The Fast Diet: revised..." by Dr Michael Mosley and Mimi Spencer. ISBN 2014 978-1-501-0201-1.  This sets out all the science and research mentioned in your review together with recipes on this method.  It was a best seller in its original publication by this BBC medical journalist and diet feature writer.  As a retired ophthalmologist i remember the dramatic effects of strict dieting by diabetics, in particular one patient whose florid proliferative diabetic retinopathy disappeared over about 4 months when prescribed laser ablation, which finally she did not need, following massive weight loss and recovery of control!   She said she was so frightened by the prospect of laser treatment that her motivation for following advice on improving blood glucose control was stimulated! 

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Dr. Jitendra Rathod|  Surgery, Cardiothoracic 4 hours ago
Quite fascinating article.There are  Hindus and Jain community in India who fast on "regular basis".For example many Hindus fast on each particular day in week,some on 11th day of Lunar Month.(depending on their belief system,customs ;from early childhood and adolescence.

Some Jain holy men and women fast for days and weeks as part of penance.

I wonder how their body and immune system adjust ?

Do they have lesser risks for Cardiovascular,and stroke events ?

And if they suffer from malignancy do fasting really help to combat malignant  process in the body ?

Another area to explore is Meditation ,in particular "Pranayam"-observing just the movements of Inhalation,Pause and exhalation.-with NO thought process.

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Dr. Alea Morningstar|  Emergency Medicine 13 hours ago
Once again the REAL reason shones thru in thei article--aha! A DRUG to mimic fasting! THERE is the reason for this article. Never mind that spiritual paths all over the world have fasted for clarity for millennia...

LETS CREATE A DRUG SHORT CUT EASY WAY AND MAKE MILLIONS!

YAY! FINALLY A WAY TO LOSE WEIGHT WITHOUT STOPPING THE MOUTH CONSUMING EVERYTHING IN SIGHT!

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Dr. John Lawton McBrayer|  HIV/AIDS 5 hours ago
Chill with the YELLING. How’s that BP doc?

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Martha Kaulback|  Registered Nurse (RN) 41 minutes ago
It’s sad that research isn’t funded without such perverse incentives.

Martha Kaulback MSN, RN

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Margaret Verni|  Registered Nurse (RN) 8 minutes ago
@Dr. Alea Morningstar  I totally agree, I was frustrated that the article ended that way, too. I do believe we are raising a drug dependent generation, as we are constantly presenting them (and us) a drug for every problem.  Then we wonder why we have a problem with drug addiction and drug related death.   We need to be encouraging the natural path to health as much as possible.  Not only is it  physically beneficial to promote the body's natural healing abilities, but it is psychologically empowering to take control of your own health and not rely on a chemical.  I believe we are hurting ourselves and the chemistry of our planet with the over use of chemicals/drugs, and I am not sure why the environmentalists are not taking up this fight. If fasting proves to be helpful for our bodies, let's fast.  Why would we substitute this natural ability with a chemical?

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Dr. Paul Parker|  Pediatrics, General 14 hours ago
Interesting how it sometimes takes science decades or even centuries to prove what certain religious or spiritual traditions have practiced and benefited from for years. Ramadan fasting has been practiced for millenia. Mormons practice fasting (24 hours) monthly. Science is only now beginning to demonstrate the carcinogenic risks of alcohol consumption, abstinence from which has long been advocated by Muslims, Seventh Day Adventists and Mormons. Joseph Smith (Mormon prophet) advocated for abstinence from tobacco (smoked or chewed) two hundred years ago. It took science another 150 years to prove it's devastating effects on the human body.

Now the scientific community needs to have marijuana in it's cross-hairs. Far too little is known of it's detrimental effects (as well as any possible medicinal benefits) and indiscriminate legalization is short-sighted and will result in long-lasting deleterious health consequences for our population.

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Dr. John Lawton McBrayer|  HIV/AIDS 5 hours ago
I have been doing a little research on canabanoids and they are quite even naturally spread throughout our brains. We focus on about 7 neurotransmitters while we are clueless about the 100 others including more neuropeptides. It’s frankly absurd. We are playing chemistry set with our pts brains.

Then there is the Japan paradox. They live the longest but smoke like smokestacks! Is tobacco the devil or daemon we make it out to be or is stress, nutrition, culture and our communities a more important factor (Kawachi)?

We are all super-learned folks but the problem is we really don’t have much to learn as we know so very little.

Docs and egos!

JLM

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Margaret Verni|  Registered Nurse (RN) 7 minutes ago
@Dr. Paul Parker  Yes!

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Dr. emilio gonzalez|  Rheumatology 2 days ago
Don Quijote (Don Quixote) in the Spanish novel by Miguel de Cervantes, 1605 and 1615, said: "Nunca te arrepientas de haber comido poco". Translation: Never regret having eaten just a little,

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Marie-Clare Oliver|  Other Healthcare Provider 2 days ago
I am very surprised you have not included any work from Dr Michelle Harvie in this review. She is a leading research dietitian in intermittent fasting diets and is using it clinically.

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Dr. John Madany|  Family Medicine 3 days ago
Anecdotally I did intermittent fasting for two months. Serendipitousl I had a baseline DEXA scan for body composition shortly before experimenting with fasting. After 7 23 hour fasts in two months I lost 7 pounds of fat and no muscle loss.(This was after five years of a low sugar/starch diet and complete resolution of the manifestations of metabolic syndrome.) I was excited to find something that could help me feel even better than I thought I ever could.

No I use it with my most Metabolically challenged patients and they are having great success.

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Dr. John Lawton McBrayer|  HIV/AIDS 5 hours ago
That’s cool!

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Dr. Victor Taylor|  Pain Management 3 days ago
Interesting article and as always interesting comments form my colleagues.

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Dr. Michael German|  Otolaryngology 3 days ago
Humans were probably meant to fast. We did not evolve with grocery stores, packaged foods, preservatives, etc and there were undoubtedly days of meager rations that induced ketosis. Our bodies are equipped to handle hunger, not a BMI of 40+. Whether it is actually “healthier” or leads to longevity is another matter. As physicians I think we all know that overnourishment is unequivocally unhealthy.

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Dr. John Lawton McBrayer|  HIV/AIDS 5 hours ago
Agreed, and all epidemiological data is clear on that subject!

Evolution is slow, not always viral and other mutations aside, we are hunter-gathers biologically speaking and would come across a treasure trove of food here and there and be without for periods of time as well.

Taking that into consideration, it seems wise to eat as we are physiologically designed to eat, unless a evidence-based better approach becomes clear!

Eat like a Cave Person (like the gender neutrality)!

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Dr. Rachel Knox 3 days ago
No body has concern or disgust over this? “In accompanying media coverage,[11] the team expressed hope that one day, these results would lead to the creation of a drug that mimics fasting without the actual need for fasting. If these and other like-minded researchers are able to make good on their aspirations, in the future it may be fine once again to treat that growling in your stomach with a trip to the refrigerator, so long as you stop by your medicine cabinet for dessert.” This is exactly one of the medical establishment’s greatest problems - solving everything with pills instead of living a natural order. Appalled.

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Dr. Miguel Gonzalez|  Psychiatry/Mental Health 4 hours ago
Dear colleague..

Eat the meat,and throw the bones.

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Dr. irina Mikhailichenko|  General Practice 3 days ago
Benefts of fasting have been known for centuries.  Most of people nowadays - involved in the field of Medicine or not, read or heard about it. Some practiced it and benefited from it. I do not see how "researchers presenting an increasingly compelling case" is going to influence it one way or another.  Even when I was a Medical Intern, we presented "The Whole30" diet, Ketogenic diet, Mediterranean diet, etc., to our patients

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Dr. WILLIAM HOH 3 days ago
This article and reading the discussion makes me want to go to McDonald's and order a Big Mac and some salted French fries

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Dr. Andre Kruger|  General Practice 2 days ago
@Dr. WILLIAM HOH Just make sure your funeral policy is paid up...

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Dr. WILLIAM HOH 3 days ago
What happened to just eating in moderation? Quick fixes always have problems that come up later.

And before you recommend, many medications need to be taken with food. Fasting will make gastroesophageal reflux disorder worse. And that's just off the top of my head

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Dr. Tim Hogan|  Family Medicine 3 days ago
But weight loss drastically improves reflux, so if the fasting can eventually lead to weight loss, it would likely help.

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Pamela Moser|  Health Business/Administration 3 days ago
@Dr. WILLIAM HOH But "with food" does NOT translate or morph into "with a large, high-calorie meal or snack". I have one medication that directs that it be taken with food. I've been taking it for years, and it works very nicely when I take it with a small quantity of something benign, like a small (1/4 cup) serving of low-calorie/carb/fat pudding or yogurt, cottage cheese, even a thick soup, a small piece of bread, etc. My stomach does not rebel at this practice, and this would hardly serve to completely render the fast useless. P. Moser, BS, MS, CTR, EAP-1

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Dr. Andre Kruger|  General Practice 2 days ago
@Dr. WILLIAM HOH In my experience (more than 10 000 fasting patients) reflux disease resolves on the second to third day in the majority of cases.

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Dr. David Bruce|  Dermatology, General 19 hours ago
@Dr. WILLIAM HOH The problem with eating in moderation is, people don't. 

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Dr. Vincent Tedone|  Orthopaedic Surgery 3 days ago
I have been intermittent fasting for several years. Have lost weight and gone from prediabetic to normal blood sugar and maintain my BP below 130/70 with the use of a calcium channel blocker. At age 83 this is the only medication I take.

I eat in a 4 hour window btw 4 and 8 pm. And am on a ketogenic diet for 5 or 6 days out of 7.

My mind is clear as a bell and have a good energy level.

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Dr. Micahel Moharan|  Family Medicine 3 days ago
Islam had called for 2 days of fasting a week and 5 days of normal eating , for more than 1400 years .

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Dr. howard schranz|  Anesthesiology 3 days ago
@Dr. Micahel Moharan But it was for spiritual reasons. They never claimed it had heath benefits.

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Pamela Moser|  Health Business/Administration 3 days ago
@Dr. howard schranz @Dr. Micahel Moharan What difference does it make what the "intent" is, if the physical result is healthful!

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Dr. Rachel Knox 3 days ago
@Dr. howard schranz in most spirituality-centered cultures, spiritual practices ARE health practices

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Dr. Richard Free|  General Practice 2 days ago
The five so called Blue Zones of unusual human longevity includes at least three islands (Sardinia, Ikaria, and Okinawa) that were significant for caloric insufficiency (and a plant dominant diet) in the 30-40 year old population (due to diversion of foodstuffs to the frontline and occupying German and Japanese troops) over a significant wartime and post war interval...these individuals now demonstrate above average longevity and survival into the ninth and tenth decades. There is a social cohesion factor and an active frequent low level exercise component in common as well...as for a specific spiritual connection, I might add, Catholics, Orthodox, and Buddhists, (and Loma Linda Seventh Day Adventist Protestants) all are represented in the five Blue Zone region populations.

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Dr. emilio gonzalez|  Rheumatology 2 days ago
@Dr. Richard Free In the region of Vilcabamba in Ecuador, South America, a mountainous region, its inhabitants often live past 100 years; it is called the valley of longevity, 

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Dr. M.D.R Hassan|  Surgery, Other 4 hours ago
Prophet Muhammad actually have said that the best fasting is the fast of prophet David which is alternate day fasting. Second best is twice a week on Thursday and Monday including 3 days the middle of Islamic month when the moon is full. He didn’t say the ‘best’ as for health specifically and we muslim take it as for spiritual definition. Apparently 1439 years later, scientists have discovered the true meaning of the best as for health as well. Peace be upon him.

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Dr. Rafik Kashlan|  Surgery, General 3 days ago
@Dr. Micahel Moharan Actually In Islam we ,Muslims , fast COMPLETELY ie no solid and no liquids including water  in  the month of Ramadan 30 days periods every lunar year . from dawn to sunset . this averages 8_9 hours in winter  10_15 hours in summer!

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Dr. Andre Kruger|  General Practice 5 hours ago
@Dr. Rafik Kashlan @Dr. Micahel Moharan I have many muslim patients and as I pointed out to a meeting of the local Muslim Medical Association (colleagues) applying the term "fasting" here is scientifically incorrect. Fasting starts when ketosis sets in. In some of my patients it take up to 3 days for a "full" ketosis (supplying all needed energy from stores)..

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Dr. charles cooper|  Anesthesiology 3 days ago
And there are psychological/spiritual benefits to the discipline of periodic fasting.

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Dr. Victor Battles 3 days ago
@Dr. charles cooper Absolutely.

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Dr. David Wallenstein|  Internal Medicine 3 days ago
Very interesting!  I recall a comment made by Nobel Laureate Rita Levi-Montalcini at the end of her life, age 102, about her secret to longevity: little food and no husband.  I have no comment about Montalcini's second secret but her first sounds like an intriguing possibility that needs further investigation for its salutary benefits and most appropriate applications!  How do I sign up?

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Dr. Laura Landrieu|  Radiology 3 days ago
I have been intermittent fasting for about a year (one three-day fast) and daily restricted eating window fasting (16:8) and, along with a ketogenic diet, have lost significant weight and improved my wellbeing to the point of weighing less than I ever have in my adult life or adolescence (been overweight to varying degrees since puberty) and am feeling strong, healthy and dare I say, at 53 years old, attractive. My blood markers are great. I’m drinking the kool aid of the benefits which I’ve also read include anti cancer and anti Alzheimer’s properties. Dr Jason Fung has plenty of information available regarding fasting and would recommend looking him up if your curiosity is piqued.

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Christine Trimpe|  Health Business/Administration 20 hours ago
@Dr. Laura Landrieu the work of Dr. Fung completely changed my life.  I have had the same experiences you mention.  Down 100 lbs, all metabolic dysfunctions reversed, amazing energy 24/7.  I have practiced IF for the past 18 months along with a strict Keto diet.  I feel better at 51 than I have ever felt in my life.  Including my chubby teenage years.  And I weigh less than I did when I went away to college at age 18.  Cheers to that Kool-Aid and congrats on your journey!

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Dr. Tomasz Helenowski|  Neurosurgery 3 days ago
Thank you! This is the most rational article I have read on dieting. As mentioned by Dr. Kruger, this will be very difficult to research properly due to lack of funding. The outcome of the studies would be difficult to exploit financially and simultaneously drag down the profits of the food and diet industries.

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Dr. Andre Kruger|  General Practice 3 days ago
I've been practicing and supervising fasting for about 40 years. Several thousand patients' full clinical, biochemical and serological profiles attest to this being superior to pharmacological intervention in most cases. By definition a fast implies nothing with taste entering the mouth... thus water only for more than 24 hours after the previous meal. The longest I have personally supervised was 45 days... resolved the patients's diabetes, heart failure, impaired kidney function, to some extent fatty liver... and I personally never eat more than 6 consecutive days. Difficult to get funding for formal research since this would NOT be in the financial interest of the pharmaceutical industry. Yet we should take hands in the interest of our patients...

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