Scientists Discover That Fasting Triggers Stem Cell Regeneration, Fights Cancer & Protects The Heart


Fasting isn’t something reserved by those who choose to do so. In fact, if you think about last time you had the flu, or were very ill, you might remember that you instinctively abstained from food. This is the same behaviour that a non-human animal might behave when they are injured or sick – they’ll instinctively refuse food until they feel better.

Fasting has been performed for many reasons other than just health. It has been done to achieve spiritual enlightenment and is practiced by many religions all around the world.

Fortunately, fasting does have beneficial effects on the body, most of which have been more recently studied, such as one study that investigated the effects of fasting on regenerative and reversing immunosuppression (aka. fasting strengthens the immune system).

This is particularly exciting news for anyone who is immunocompromised, because it is free, and is believed to work even in the elderly.

Just Three Days for a New Immune System

According to a new study carried out by researchers at the University of Southern California, fasting for just 72 hours (three days), can regenerate the entire immune system, even in elderly people.

The researchers state that fasting helps the body’s stem cells to start producing new white blood cells, whose role is to fight off infection in the body. They added that the three-day water fast could be especially effective for those suffering from immunocompromised systems, such as chemotherapy patients (they found that chemotherapy patients who fasted were better protected from the toxic impacts of the treatment).

Flipping a “Regenerative Switch”

Prolonged fasting breaks down a significant amount of white blood cells, which induces changes that trigger stem cell-based regeneration of new immune system cells.

Dr. Valter Longo, Professor of Gerontology and the Biological Sciences at the University of Southern California, stated that fasting gives the immune system “the ‘OK” for stem cells to go ahead and begin proliferating and rebuild the entire system (1).” He later added that the body gets rid of the parts of the system that might be old or damaged (the inefficient parts) during fasting, creating “literally, a new immune system.”

Dr. Longo describes that in order to create energy while fasting, the body must recycle unneeded immune cells (especially damaged ones). Over the course of his study’s trials, participants were asked to regularly fast between 2-4 days over a 6-month period. Although clinical trials still need to be completed, he is convinced that his research is “very promising,” and would benefit the population at large.

Other Benefits of Fasting

Although it is not advised to fast longer than 2-3 days, it does have its benefits. Any fast longer than 2-3 days should be supervised if you’re struggling with disease or illness, or have been leading an unhealthy lifestyle for most of your life. Intermittent fasting is much safer, too, although the effects will not be as profound (however, will still be incredibly beneficial). Intermittent fasting works by eating in an 8-hour window, for example, eating from 11am-7pm, and nothing else but water outside that time frame.

1. It Weakens Cancer

Scientists also found that prolonged fasting reduces the enzyme PKA (2), which is linked to aging and a hormone (IGF-1), which increases cancer risk and tumour growth. Dr. Longo explains that PKA needs to shut down first in order for stem cells to start regenerating and rebuild the immune system – and fasting does just that.

Another study published in the journal Science Translational Medicine found that five out of eight cancer types responded positively to fasting (3). It improved survival rates by slowing the growth and spread of tumours.

The study found that fasting cycles without chemotherapy slowed the growth of melanoma, glioma, human neuroblastoma and breast cancer in mice. In several cases, fasting for up to 72 hours was as effective as chemotherapy.

Fasting causes cellular activity to slow down in normal cells, however, in cancerous cells (particularly breast cancer cells), it causes the growth of new proteins, which encourages the tumour to grow and divide. This survival mechanism played out by cancer cells essentially causes it to self-destruct, as a result of the creation of damaging free radical molecules that break down the cancerous cell’s DNA.

“The cell is, in fact, committing cellular suicide. What we’re seeing is that the cancer cell tries to compensate for the lack of all these things missing in the blood after fasting. It may be trying to replace them, but it can’t,” Dr. Longo explains.

2. It Protects The Brain

Fasting can also protect against different diseases of the brain, according to US scientists.

Researchers at the National Institute on Ageing in Baltimore found evidence which showed that periods of stopping all food intake for 1-2 days a week could protect the brain against neurodegenerative diseases like Alzheimer’s, Parkinson’s and other ailments (4). Fasting, or limiting food intake to 500 calories for 1-2 days a week doesn’t only improve brain health, but it also increases longevity, too.

3. It Reduces The Risk of Heart Disease and Diabetes

Occasional water-only fasts also lower your risk of developing heart disease and diabetes.

In a study conducted in Utah, researchers found that Mormons who fasted for 24 hours once a month for religious purposes, had much better arterial health than non-fasters (5). “X-ray scans revealed narrowing of the arteries in around 75 per cent of those who didn’t fast. In contrast, clogged arteries affected 63 percent of those who said they often skipped meals.”

The study also found a reduction in levels of blood sugar and dangerous blood fats called triglycerides.

It should also be mentioned that fasting triggers a surge in the human growth hormone (6), which speeds up metabolism and burns up fat, ultimately lowering your risk of diabetes.

Carly Fraser has her BSc (Hons.) Degree in Neuroscience, and is the owner and founder at Live Love Fruit. She currently lives in Winnipeg, Manitoba, with a determined life mission to help inspire and motivate individuals to critically think about what they put in their bodies and to find balance through nutrition and lifestyle. She has helped hundreds of thousands of individuals to re-connect with their bodies and learn self-love through proper eating habits and natural living. She loves to do yoga, dance, and immerse herself in nature.


  1. thanks for the confirmation that my 3 day water fast every 9 days are a great part of healing stage 4 cancer.
    I knew it!!! 🙂
    dawna masters

  2. Hi Carly, this is great however, would like clarification on the following:
    1) At what age is it safe for one to start fasting?
    2) If one is extremely active, fasting is usually not the best thing due to requiring fuel for one's body?
    3) What would a complete fast entail? Water only with nothing else or is it at one's discretion.. i am Christian and i like to fast for 1 day a month… i am thinking about fasting 1 day a week in fact however only for 24 hours not for longer than that… what is a good recommendation?
    Thanks so much

    • Hey Cherie,

      If you have any health conditions, I suggest not going longer than a couple days on your fast unless you are monitored by a health professional. I think anyone can do a fast at any age, given you are in good shape, and don't have any lingering health conditions. If you're extremely active, probably not a good idea to fast – I would suggest setting aside time when you are not active to fast. A complete fast entails just pure filtered water – nothing elese.

  3. I had stage II A breast cancer a very rare cancer that was slow growing living off my female hormones only. I am 43 and my body has natural days of not wanting to eat on and off through weeks. I was 200lbs. Due to pregnancy and had lost only 30 lbs after I had my daughter. She is almost 6 years old and this last 5 months I have been fastening due to stressful issues in my life. I lost 10 lbs. from it and than had reconstruction breast surgery a week ago. Should I still stick to fastening while I recover for the next 2-6 weeks?


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