Nutritional therapy (NT) plays a critical role in the management of critically ill patients on mechanical ventilation (MV) and during weaning. Early NT, preferably by enteral route, improves clinical outcomes by reducing complications such as infection and loss of lean body mass. The NUTRIC score and NRS-2002 are screening tools to identify nutritional risk and guide individualized interventions. Strategies for feeding the critically ill patient at different stages of critical illness should be implemented. During the acute phase, NT should be started slowly and gradually, adjusted according to gastrointestinal and metabolic tolerance. Avoidance of overfeeding is essential, as excess calories increase CO2 production, complicating weaning from MV and prolonging ventilator dependence. Weaning from MV requires continuous nutritional care. Inadequate protein and energy intake can impair muscle strength, especially diaphragmatic strength, which is essential for return to spontaneous ventilation. Strategies include monitoring of nitrogen balance and periodic nutritional reassessment to adjust caloric-protein targets. Attention must be maintained after extubation, as oral intake rarely meets nutritional requirements. Studies emphasize the importance of early mobilization and protein supplementation in maintaining muscle function and rehabilitating post-ICU syndrome (PICS). Integration of NT with other facets of rehabilitation, such as early mobilization, is essential to optimize clinical and functional outcomes, facilitate weaning, and accelerate recovery in critically ill patients.