A growing body of research suggests that short-term fasting could do more than help with weight loss; it might give your immune system a reboot.
Studies led by Dr Valter Longo at the University of Southern California show that fasting for 48-72 hours can trigger remarkable changes in the body’s immune system, at least in mice and promising early results are emerging in humans.
In these studies, prolonged fasting lowers certain growth signals in the body, such as IGF-1 and reduces PKA activity. In mice, this results in the clearance of old, worn-out immune cells and the production of fresh, healthy white blood cells. Essentially, the immune system appears to “refresh” itself after a fasting period.
Early human trials, mostly involving cancer patients undergoing chemotherapy, hint at similar effects. Short fasting cycles, often 72 hours around chemotherapy, were found to be safe under medical supervision and were associated with improved immune markers and reduced side effects from treatment.
Other studies exploring “fasting-mimicking diets” carefully designed low-calorie, plant-based meals for several days show that even without complete fasting, people can experience shifts in blood cell profiles that resemble a younger, healthier immune system.
However, experts caution against interpreting these findings as a guarantee. The dramatic immune “reset” seen in mice has not yet been conclusively proven in humans. The human studies are small and fasting for extended periods can carry risks if done without supervision.
Still, the research is exciting. It points toward a future where controlled fasting or fasting-mimicking diets could become tools to support immunity. While it’s not a magic bullet, it’s a fascinating reminder that sometimes, giving the body a break can help it start anew.
