The designation of " Weight Management Year " has stimulated substantial discourse on obesity. While obesity constitutes an established risk factor for various malignancies its association with radiotherapeutic efficacy manifests a paradoxical phenomenon termed the " obesity paradox" in oncologic radiotherapy. This paradox poses a challenge to traditional public health perceptions. Emerging evidence indicates that obese patients may demonstrate enhanced radiosensitivity. Yet obesity can adversely influence therapeutic outcomes through alterations in the tumor microenvironment and modulation of radiotherapy - related adverse effects. In addition to the body mass index which is a conventional clinical indicator used to define obesity more detailed body composition analyses based on computed tomography scans can also be employed to assess obesity. Emerging evidence suggests that the distribution of adipose tissue in different regions of the body may have a complex and sometimes contradictory relationship with the prognosis of obese cancer patients undergoing radiotherapy. Consequently a comprehensive elucidation of these complex interactions is imperative for optimizing radiotherapy protocols and improving patient prognoses. This review aims to evaluate the impact of the obesity paradox on radiotherapeutic efficacy formulate clinical strategies for addressing the obesity paradox and delineate future research directions.