We evolve and become stronger when we face challenges, but if the demands become too great, then burnout lurks around the corner and we can get sick. The cells within our bodies appear to function in the same way. They are made stronger by challenges such as exercise and fasting, but not if it is overdone. The question then, what dose of challenge is just right?

There is a substance called rapamycin that can trigger the body to initiate processes similar to what happens when we fast. The molecule has been shown to extend life in mice by up to 30 percent and many are interested in experimenting with this “ life elixir”, but there is one major problem: the dosage.

Low doses of rapamycin strengthen the immune system. While high doses, on the contrary, cause the immune system to shut down. The immune cells become so inactive that rapamycin is currently used as a drug in transplants to prevent the new organ from being rejected.

The effect of rapamycin is due to its ability to inhibit the protein complex mTOR (Mammalian Target of Rapamycin). It is a central regulator for growth, health and aging. Fasting also inhibits mTOR and is free, unlike rapamycin, plus there’s no need to think about dosage … or is there?

Well, it seems that fasting just like rapamycin can make the immune system both stronger and weaker depending on the dose. Cell magazine brings together several studies in the field in a recent issue.

The results indicate that complete fasting over several days weakens the immune system. Complete fasting for a day reinforces it, but you also get a boost just by halving food intake for a day. Fasting is a powerful tool and the effects can be very positive, but you should have respect for the processes that can be triggered and avoid going at it too hard.

Most things today indicate that there are no good reasons for complete fasting (just drinking water). In addition to immunity risks, there are signs that the gut bacteria can be adversely affected.

Complete fasting isn’t really that natural if you think about it. Historically, man has always been able to find something to put in his mouth even during a famine. If you are going to fast for positive health effects, it is safest to cut down on food for a period of time rather than complete fast.

Researcher Valter Longo has tried to find a “sweet spot” with the food intake during a fast that gives the best health effects and optimal effect of mTOR. He tried a variety of fasting regimens on mice and eventually came to what is known as the “Fasting Mimicking Diet” or fasting diet. This diet takes the form of reducing calories to about one third of a normal daily intake for five days.

However, that being said, all types of fasting do provide some form of effect. It is important to find a way that suits you best. As more and more studies are done, we will probably also see different schedules according to what you want to achieve. Weight loss? Counteract autoimmunity? Achieve mental focus? Strengthen the immune system before a long journey? This is an exciting development that I look forward to following and telling more about here at Food Pharmacy.

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