Joseph discusses the transformative effects of the fasting mimicking diet on gut health, particularly in relation to leaky gut and autoimmune conditions like ulcerative colitis and Crohn's disease. He highlights how fasting reduces pro-inflammatory markers and promotes the rejuvenation of gut cells, ultimately aiding in the healing of damaged organs. The process helps the body eliminate harmful immune cells while fostering the generation of new, non-inflammatory white blood cells, addressing root causes of inflammation.