Enteral nutrition responsiveness in critically ill patients: An expert commentary

Clinical decisions about enteral nutrition timing and dose in critically ill adults are largely guided by visible markers of feeding intolerance (e.g., vomiting, ileus), which signal dysmotility risk but provide little insight into nutrient assimilation or metabolic benefit. This creates a "visibility problem," whereby practice is shaped by observable adverse effects rather than nutritional effectiveness. We propose a phase-specific framework that conceptualizes enteral nutrition as a titratable therapy based on biologic responsiveness. Enteral nutrition responsiveness is defined as the likelihood that delivered nutrients achieve phase-specific therapeutic goals within physiologic and metabolic constraints. Reinterpretation of trials comparing restricted versus full-dose enteral nutrition suggests that during the acute phase, many patients have limited responsiveness to higher doses, consistent with a narrow therapeutic window in which the primary rationale for feeding may be gut barrier support rather than correction of energy deficits. As patients transition into later phases, physiologic stability improves, and enteral nutrition responsiveness increasingly reflects nutrient assimilation and metabolic utilization that may contribute to recovery. Conceptualizing enteral nutrition as a phase-dependent, titratable therapy may help reconcile conflicting trial data, support individualized strategies, and highlight the need for bedside tools and biomarkers that assess nutrient assimilation and utilization rather than delivery alone.