RESUMEN
OBJECTIVE: The present study aimed to evaluate the association between muscle mass variation, estimated by different equations, during hospitalization with the energy and protein intake and clinical and nutrition outcomes of patients using nutrition support. METHODS: A prospective observational study with patients older than 18 years in use of enteral and/or parenteral nutrition therapy and monitored by the Nutritional Therapy Committee between December 14, 2021, and December 14, 2022. Data were collected from the electronic records and were applied in 11 equations to estimate the four different portions of muscle mass of patients receiving nutrition support at the beginning and the end of hospitalization. RESULTS: A total of 261 patients were evaluated, with a median age of 61.0 (49.0-69.75) years, and 106 were women (40.6%). According to the nutrition diagnosis, several participants had severe malnutrition (39.5%). The most muscle mass estimation equations indicated a reduction of muscle mass during hospitalization. All patients presented negative energy and protein balances during hospitalization, but greater protein intake increased the lean soft tissue. Also, the greater the number of infections, metabolic complications, and scheduled diet interruption, the greater was the chance of losing muscle mass. CONCLUSION: There can be an association between the variation in muscle mass and energy and protein intake during hospitalization of patients using nutrition support. In addition, variation in muscle mass was associated with complications from nutrition support. The results emphasize the importance of anthropometric measurements to estimate muscle mass when other methods are not available.