The immune system is a double edged sword. With remarkable strength it protects us from external threats, but with time it can also cause age related sicknesses. If we could regulate the immune system, much would be won. Fasting can be a tool for that.

In the unceasing struggle for survival, our bodies have developed an intricate system to protect us from external threats, such as bacteria, virus, fungus, parasites and other “nasty things”. The immune system is constantly on watch with its soldiers (macraphages), intelligence (lymphocytes) and weapon systems (cytokines). It also watches for inner threats like malignant cells causing cancer.

But this readiness comes at a price. Immune cells that are on a constant watch for enemies can get the idea that healthy tissue is a problem – and attack it. This triggers auto immunity and inflammatory conditions, such as MS that destroys the protective layer of the nerves, or rheumatoid arthritis that attacks the joints. There are of course many other diseases with underlying inflammatory reactions.

With age, the immune system gets worse at fighting microbes, and inflammation increases. This chronic inflammation drives aging and sickness, but the pattern is complex and hard to act on. If you want to medically dampen the immune system, you also have to make sure that you do not weaken its resistance towards microbial threats.

Enter fasting. It is known that fasting affects the immune system and an increasing number of scientist are investigating in what way. Some new studies have shown that fasting for 24 hours strengthens the immune cells, but fasting for any longer actually makes the immune system worse at fighting infections. It is also known that caloric restriction lowers symptoms of autoimmune disease.

In a study using five days of a fasting mimicking diet, the autoimmune attacks decreased when the immune cells were forced to handle food shortages. The mechanism is probably based on the fast triggering a clean-up of old immune cells. They are replaced with new ones, that are not as prone to attacking the body’s own tissue. Just imagine a kind of soft reset of the immune system.

Fasting is not a universal solution, but to now and then expose yourself to a limited period of food shortage can be good for your immune system. It can still keep the system aggressive against enemies, but all the while remaining disciplined enough to not attack itself.

This is a guest post. The opinions expressed are the writer’s own.