Study finds fasting for 72 hours induces immune system regeneration

Fasting for three days can regenerate the entire immune system and reverse the damage to the immune system done by chemotherapy.

A team of researchers at the University of Southern California have described their breakthrough as “remarkable”.

While diets and fasting have traditionally been criticized by the medical profession as unhealthy and ultimately counterproductive, these research results suggest starving the body kick-starts stem cells into producing new white blood cells, which fight off infection.

The scientists were surprised by their findings

“We could not predict that prolonged fasting would have such a remarkable effect in promoting stem cell-based regeneration of the hematopoietic system,” said Prof Valter Longo, Professor of Gerontology and the Biological Sciences at the University of California.

“When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged,” Longo said.

“What we started noticing in both our human work and animal work is that the white blood cell count goes down with prolonged fasting. Then when you re-feed, the blood cells come back. So we started thinking, well, where does it come from?”

The implications of these findings are enormous:

With a renewed immune system, we are increasing the chances of a long and healthy life.

In fact, yogis and sages have done this through the ages as we all know. Western medicine is only catching up now.

Why does prolonged fasting work so effectively?

Prolonged fasting forces the body to use stores of glucose, fat and ketones, but it also breaks down a significant portion of white blood cells.

During each cycle of fasting, this depletion of white blood cells induces changes that trigger stem cell-based regeneration of new immune system cells.

In their research, the team from the University of California gathered a group of participants and asked them, in the initial stages, to fast for 2-4 days on a regular basis over a period of six months.

This is where they made a remarkable discovery.

There was a noticeable decrease in the production of the enzyme PKA, a hormone which has been associated with an increased risk of cancer and tumor growth. In addition the immune system of the participants appeared to get renewed.

“PKA is the key gene that needs to shut down in order for these stem cells to switch into regenerative mode. It gives the OK for stem cells to go ahead and begin proliferating and rebuild the entire system,” explained Longo.

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There’s more: Prolonged fasting resets your immune system

Longo continued:

“And the good news is that the body got rid of the parts of the system that might be damaged or old, the inefficient parts, during the fasting. Now, if you start with a system heavily damaged by chemotherapy or aging, fasting cycles can generate, literally, a new immune system.”

This is truly an incredible finding.

The research findings suggest that it’s worth trying to go without food for three days to recover your immune system, rather than take expensive and potentially harmful drugs.

(If you want to learn more about natural remedies and herbal medicine, check out our The Lost Book of Remedies review).

Prolonged fasting may mitigate the harmful effects of chemotherapy

Prolonged fasting also protected against toxicity in a pilot clinical trial in which a small group of patients fasted for a 72-hour period prior to chemotherapy, which is good news for cancer patients and others who receive chemotherapy for autoimmune diseases.

“While chemotherapy saves lives, it causes significant collateral damage to the immune system. The results of this study suggest that fasting may mitigate some of the harmful effects of chemotherapy,” said co-author Tanya Dorff, assistant professor of clinical medicine at USC.

She added that more clinical studies are needed, and any such dietary intervention should be undertaken only under the guidance of a physician.

Also, it’s possible that the effects of fasting is not limited to the immune system. Scientists are looking into the possibility that these effects are applicable to many different systems and organs in the body.

Additional benefits of prolonged fasting

Scientists are starting to establish the benefits of fasting to the immune system. What are some of the other benefits you could expect from prolonged fasting?

You can expect to experience these benefits:

  • You will likely experience weight loss. There is a number of reasons for this. First, you’ll lose weight because you’ll lose a lot of water from depleting glycogen in the liver and muscles. This is why you’ll often hear that it’s important to increase your water intake during prolonged fasting. In any case, depleting your glycogen levels will achieve a metabolic state of ketosis, turning you into a fat burning machine. Quick note: Prolonged fasting isn’t a permanent method for weight loss as you’ll likely put it back on when you start eating again.
  • Your body will “start to eat itself”, a process known as autophagy. Autophagy recycles waste from the body and repairs any oxidative stress.
  • You will likely experience cognitive benefits from prolonged fasting. This makes sense when you think about it. When we were hunters and gatherers and we hadn’t eaten for a few days, we needed to come up with new ideas in order to find more food. Our ability to think critically would have improved in these circumstances. Some research suggests that ketosis is advantageous for the brain, resulting in more brain-derived neurotrophic factor or BDNF.

(If you want a healthy, sustainable diet plan, check out our Custom Keto Diet review).

Is prolonged fasting the same as intermittent fasting?

Intermittent fasting means you are introducing a schedule of prolonged fasting into your eating routines.

For example, you may fast for 16 hours per day, only eating within an 8 hour window (eating between 11am and 7pm, fasting between 7pm and 11am the next day). Doing this every day, or 5 days per week, means you are adopting an intermittent fasting schedule.

Prolonged fasting usually refers to fasting for a period of time over 48 hours.

Viral TED talk suggests intermittent fasting boosts brain power

If you’re interested in learning more about intermittent fasting, watch the below viral TED talk on intermittent fasting and why the food industry won’t study it.

Coert Engels

Coert Engels

I'm a South African based writer and am passionate about exploring the latest ideas in artificial intelligence, robotics and nanotechnology. I also focus on the human condition, with a particular interest human intuition and creativity. To share some feedback about my articles, email me at

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