Background Prehabilitation, the process of optimizing a patient's physical and nutritional status before surgery, has gained increasing attention for its potential to improve outcomes by enhancing physiological reserves and functional capacity. While body composition may play a role in these outcomes, its specific contribution remains underexplored. This narrative review summarizes current evidence on the effects of prehabilitation on body composition, focusing on exercise, nutritional interventions, and multimodal approaches. Summary Exercise, particularly a combination of aerobic and resistance training, has been shown to improve cardiorespiratory fitness, reduce fat mass, and enhance skeletal muscle and strength. Nutritional interventions, including increased protein intake, support skeletal muscle preservation and recovery. A multimodal approach, integrating both exercise and nutrition, yields the most significant improvements in body composition, showing enhanced skeletal muscle, reduced fat mass, and better functional outcomes. However, the limited duration of prehabilitation and the time required for detectable changes in body composition often prevent consistent observations. Furthermore, variations in assessment techniques and protocols across studies confound definitive conclusions. Key messages Despite some promising results, further research is needed to standardize protocols and explore the effects of prehabilitation on body composition across diverse patient populations. Finally, further research is needed to investigate the impact of prehabilitation on measurable changes in body composition, as this represents a critical gap in the field.