Cancer remains the leading cause of morbidity and mortality worldwide, with lifestyle and dietary factors playing an important role in its prevention, progression, and management. Dietary practices are crucial in cancer prevention, with dietary choices influencing key processes such as inflammation, metabolic regulation, and carcinogenesis. Obesity and physical inactivity further exacerbate cancer risk, primarily through their impact on systemic inflammation and metabolic dysregulation. Nutritional challenges in cancer care arise from a variety of factors, including tumor-induced systemic inflammation, metabolic alterations, treatment-related side effects, and psychological stress, all of which contribute to malnutrition. Addressing these challenges requires a comprehensive understanding of the factors driving cancer-related malnutrition and its implications for public health. Systemic interventions, including policy reforms and community-based programs, are critical for reducing the burden of malnutrition among cancer patients. Evidence-based dietary guidelines provide practical recommendations to manage nutritional issues effectively and improve patient outcomes. The integration of nutritional strategies into oncology care highlights the importance of a multidisciplinary approach to addressing malnutrition and enhancing the overall quality of cancer management.