This literature review of clinical and preclinical studies aimed to analyse the latest evidence on the Mediterranean diet (MD) and intermittent fasting (IF) to prevent or delay strategies for the onset of cancer in patients with hereditary cancer syndromes, correlating the data about some nutritional, clinical biochemical, and inflammatory biomarkers (e.g. CRP, IL-6, insulin, and IGF-1). Here, INS is linked to cancer.