Protein Dosing Strategies in Critically Ill Patients: Comparing Actual Body Weight and Fat-Free Mass Approaches in an Observational Cohort Study

This study investigates how different methods of calculating protein intake affect recovery and muscle preservation in critically ill patients in the Intensive Care Unit (ICU). Protein is essential for maintaining muscle strength, supporting healing, and improving recovery during critical illness.

At Hospital Gelderse Vallei, patients admitted to the ICU received protein based on actual body weight until 2023; more recently, protein prescriptions have been based on fat-free mass. Bioelectrical impedance analysis (BIA) has been part of standard clinical practice in the ICU since April 2020, meaning that all patients admitted since then have been screened for inclusion in the study.

This design allows for comparison between two groups: one group receiving protein based on actual body weight according to current clinical guidelines (1.5 g/kg body weight), and another group whose protein intake is calculated based on lean body mass (LBM) measured by BIA. BIA measurements are repeated during the ICU stay to monitor changes in body composition.

A total of 310 patients admitted to the ICU between the start of BIA implementation in April 2020 and the transition to fat-free mass-based dosing in 2023 were identified. To allow for balanced comparison, an equal number of 310 patients from the subsequent period, in which protein dosing was based on fat-free mass, were included in the study.

The study compares these two groups to determine whether calculating protein requirements based on lean body mass leads to better clinical outcomes-such as improved recovery (lower mortality and shorter hospital stay), preservation of muscle mass, and lower UCR-than the traditional method based on actual body weight. The data analysis plan was established prior to completion of patient inclusion and database lock.