BACKGROUND: Septic shock is one of the main causes of mortality in intensive care units worldwide. Nutritional support can affect the survival of patients with sepsis. OBJECTIVE: To evaluate whether resting energy expenditure, respiratory quotient, and oxygen consumption and carbon dioxide production (measured by indirect calorimetry) differ between critically ill patients with vs without sepsis. METHODS: A total of 205 patients receiving mechanical ventilation were evaluated consecutively within the first 48 hours of admission. Demographic and clinical data were collected, including age, body mass index, oxygen consumption, carbon dioxide production, respiratory quotient, and resting energy expenditure, with the clinical data measured or estimated via indirect calorimetry. RESULTS: Of the 205 patients, 114 (56%) had no sepsis and 91 (44%) had sepsis. The median values of the studied variables in the no sepsis and sepsis groups, respectively, were as follows: age, 53 vs 58 years (P = .07); body mass index, 25 vs 26 (P = .14); Acute Physiology and Chronic Health Evaluation II score, 24 vs 25 (P = .04); death risk, 47% vs 63% (P = .04); oxygen consumption, 211 vs 202 mL/min (P = .72); and resting energy expenditure, 1434 vs 1430 kcal/d (P = .73). Analysis of receiver operating characteristic curves showed no significant differences between patients with and without sepsis for any of the indirect calorimetry variables. CONCLUSION: In clinical practice, patients with sepsis do not seem to require an increased energy supply. Additional studies are needed to confirm this conclusion.