BACKGROUND AND OBJECTIVES: It is often difficult to assess the nutritional requirements of severely injured patients. In this study, we aimed to determine whether various nutritional assessment formulas are accurate at assessing the nutritional requirements of trauma patients. METHODS AND STUDY DESIGN: We recruited trauma patients who were admitted to a trauma centre in 2018 and were identified as being at high risk for malnutrition. Energy expenditure was calculated using commonly used prediction equations, and the results were compared to resting energy expenditures measured using indirect calorimetry. RESULTS: Sixty-nine patients (78.9% men; mean age, 53.6 years) collectively underwent 95 indirect calorimetry assessments. The average resting energy expenditure was 1761.8+/-483.8 kcal/day, and the average respiratory quotient was 0.8+/-0.2. The correlations between the measured resting energy expenditures and nutritional requirements estimated by each formula were significant but weak (i.e., r-values <0.8). The Penn State formula had the highest r-value (0.742; 95% confidence interval [CI], 0.6359-0.8210), followed by the Faisy formula (0.730; 95% CI, 0.620-0.812). CONCLUSIONS: The formulapredicted nutritional requirements did not adequately correlate with the resting energy expenditures measured by indirect calorimetry. Therefore, we recommend using indirect calorimetry to assess the nutritional requirements of severely injured patients.