For patients in intensive care units, what — and how much — to feed is not a simple clinical question. Underfeeding starves healing tissues; overfeeding drives inflammatory cascades and metabolic dysfunction. Getting this balance right may be one of the most consequential yet underappreciated decisions in critical care, and a comprehensive review in the New England Journal of Medicine synthesizes the current state of evidence to guide that decision-making.
The review covers the full arc of nutritional intervention in critically ill adults, addressing route of delivery (enteral versus parenteral), caloric and protein targets, timing of initiation, and how metabolic monitoring should shape adjustments. The authors examine how acute illness profoundly alters nutrient utilization — with endogenous glucose production, muscle catabolism, and altered gut permeability each undermining assumptions borrowed from non-ICU nutrition protocols. Key emphasis is placed on the distinction between the acute inflammatory phase, when aggressive feeding may worsen outcomes, and the recovery phase, when adequate protein delivery becomes essential for preserving lean mass and functional recovery.
This review arrives at a moment when the critical care nutrition field is consolidating lessons from a series of high-profile randomized trials — including CALORIES, PermiT, and EPaNIC — that collectively overturned earlier enthusiasm for early aggressive caloric support. The emerging consensus now leans toward permissive underfeeding in early acute illness, with individualized protein targets as a priority over caloric volume. The practical implication for ICU survivors, a population at high risk for prolonged muscle weakness and functional decline, is significant. Limitations inherent to this literature include heterogeneous patient populations, variable illness severity, and the difficulty of isolating nutrition as a variable from concurrent interventions. As a synthesis of current evidence rather than a new trial, this review is best read as a calibration tool for clinicians rather than a paradigm shift — though its NEJM platform ensures it will shape practice standards broadly.
