Head and neck squamous cell carcinoma (HNSCC) is a prevalent and aggressive cancer originating from the mucosal surfaces of the head and neck region. Despite advancements in treatment, HNSCC patients face high recurrence and mortality rates. This study employs a comprehensive approach to investigate the impact of body composition changes, specifically adiposity and muscle mass, on recurrence and survival in HNSCC patients. Using multivariate logistic regression, Kaplan-Meier survival analysis, and Cox proportional hazards models, the study evaluates the significance of post-radiotherapy changes in adiposity and muscle mass. Additionally, the effectiveness of follow-up imaging modalities (MRI, PET/CT, CT) is assessed through chi-square tests and Cox regression analysis. Results indicate that increased adiposity post-radiotherapy correlates with higher recurrence and mortality rates, while muscle loss combined with adiposity gain significantly affects survival probabilities. PET/CT scans demonstrated superior efficacy in detecting recurrences and were linked to better survival outcomes compared to MRI and CT. The findings highlight the importance of monitoring body composition and strategically utilizing advanced imaging techniques in the follow-up of HNSCC patients. These insights suggest that personalized follow-up protocols could enhance patient outcomes by addressing specific risks associated with body composition changes.