Rationale: In Amyotrophic Lateral Sclerosis (ALS) hypermeta-bolism is find in 50– 60%, defined as an excessive level of resting energy expenditure (REE) >10% of theoretical value. 1919 Harris and Benedict’ s (HB) formulas are the main ones used to obtain the theoretical values, but other predictive formulas are also used in current practice. The aim of the study was to assess the level of REE in ALS patients compared to control population and using six predictive formulas of theoretical REE. Methods: Nutritional assessments were performed in ALS patient and in two control populations without hypermetabo-lism: (control 1 and 2). Weight, height and body composition by bioimpedance analysis were assessed. REE was measured (mREE) by indirect calorimetry and calculated (cREE) using 1919 HB ’ s and 1984 HB’ s formulas, and World Schofield, De Lorenzo, Johnstone and Mifflin St. Jeor formulas. Mann-Whitney and Chi2 tests were used for statistical analysis. Results: 315 ALS patients, 80 control 1 and 54 control 2 were analysed. mREE was 1,503 kcal/24 h in ALS patients, 1,220 kcal/24 h in control 1 and 1,344 kcal/24 h in control 2, higher in ALS patients vs. cREE with all formulas (p < 0.0001) and higher vs. control 1 and control 2 (respectively p < 0.0002 and <0.0001). Depending on the predictive equation, hyper-metabolism was found in 46.7% to 73.7% of ALS patients, with REE variation of +8.1% to +19.0%. Percentage of hypermetabolism and REE variation with the six formulas were higher in ALS patients versus control (p < 0.0001). Mifflin formulas produced he lowest values of cREE, and the highest for percentage of hypermetabolism and REE variation. Conclusion: Compared to control populations, hypermetabo-lism is confirmed in ALS patients. It is present with the six REE predictive formulas used, but Mifflin equation seems the least adapted.