Dear Editor,

We thank Dr. Bitzani for her thoughtful letter [1] regarding our initial article [2]. We agree completely that “the issue of optimal nutrition delivery in this patient group is still largely unclear” and therefore believe that it is inappropriate to make strong recommendations regarding the provision of calories and protein in this heterogenous group of patients [3]. It is noteworthy that the mean amount of calories delivered in the “normocaloric” arm of the trophic and permissive underfeeding groups was 1359 and 1246 kcal/day, respectively. It is therefore most unlikely that these patients were overfed, as suggested by Dr. Bitzani. Indeed, some experts have suggested that the failure of these trials to demonstrate a benefit of normocaloric feeding is because the patients in the “normocaloric” arms were underfed. Critical illness is associated with the severe loss of muscle mass which is associated with serious long-term disability [4, 5]. The excess provision of protein has been directly correlated with the degree of muscle loss [4]. Multiple experimental models and real-life clinical observations have clearly demonstrated that the continuous provision of high doses of amino acids compromise muscle protein synthesis [6]. The recommendation in the current guidelines that “protein requirements are expected to be in the range of 1.2–2.0 g/kg/day” [3] is likely to be harmful in critically ill patients (when given as a continuous infusion) [6]. It is important to emphasize that there is no high-quality evidence in critically ill or injured patients that one particular nutritional strategy is associated with better patient outcomes than another. Our approach is quite simple; use the gut, do it slowly, do it intermittently, and use a high-quality formula.