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How fasting can regenerate immune cells

by Rebecca Goad on February 08, 2023

 Immune System man stopping virus cells

What defines a fast?

So let’s start with the basics. It’s essentially when you completely, or almost completely, stop eating for a prolonged amount of time. You’ve probably heard of intermittent fasting as it has recently gained popularity in the health and wellness world. 

Intermittent Fasting

David Medasky, who was on our podcast, says

“Intermittent fasting is where you go anywhere from 12 to 16 hours without eating food. And most people do it normally. If you go to bed at ten o'clock at night and you stop eating at seven o'clock, three hours before and you have your first meal at seven or eight o'clock in the morning, you've done an intermittent fast”.

What does the science say?

A study explored the idea of fasting for 3 days and more, only drinking water and eating only 200 calories and less can almost ‘reset’ some components of your immune system.
This study looked at the effects of fasting in both mice and humans and found that in both species that fasting increased white blood cells as fasting sees the body’s white blood cell count to decrease which then triggers the formation of new white blood cells. And we know that white blood cells, aka lymphocytes play an essential role in the immune system. 

Longo’s hypothesis is that prolonged fasting forces your body to “recycle a lot of the immune cells that are not needed” which is why the decrease in the white blood cell count is seen.


Two of the key mechanisms are an enzyme called PKA and a hormone called IGF-1, both of which are reduced by fasting. Once you start eating again, your stem cells kick back into high gear to replenish the cells that were recycled.

This same study explored cancer patients fasting for 1, 2 or 3 days before undergoing chemotherapy and saw that the fasting reduced the harmful side effects of chemotherapy, more specifically the immunosuppression caused by the treatment.

Now we aren’t saying you need to be fasting for days on end because let’s be honest, for a lot of us that would be unfeasible as we can’t go without more than 2 meals without having serious hanger. But trying to perform intermittent fasting every so often could do your immune system some good.

So why not set your alarm an hour or two later than usual and wake up with a big glass of water and hey, call it intermittent fasting! 


We need to make it known that fasting can be extremely harmful if you have other health problems and can be triggering to those who have eating disorders so please consult your physician if you’re thinking of trying this.


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