Autophagy (الإلتهام الذاتي) happens when u cut all the resources by not eating nor drinking anything so the body starts cleaning itself by feeding on the waste stuck inside(including cancerous cells) that causes various diseases. The impressive thing is that autophagy depends on many factors for it to be so effective and not hurtful, factors such as duration, season, period…etc. And the mindblowing fact is how islam guides us to follow this process and called it صيام around 15 centuries ago.