Definition
Hormesis
The principle that a small, controlled dose of a stressor, such as exercise, heat, or cold, triggers an adaptive response that leaves the body more resilient.
Hormesis describes how mild stressors — resistance training, sauna heat, cold exposure, brief fasting — below a harmful threshold prompt the body to adapt and strengthen, whereas the same stressor at high, sustained intensity causes damage instead. The dose determines whether it helps or harms.
Why it matters: it explains why moderate, intentional discomfort such as exercise or heat and cold exposure builds resilience, while chronic unmanaged stress of the same categories degrades it. The difference is dose and recovery, not the stressor itself.
Related terms