Precision nutrition in critical illness: a phase-specific framework from acute feeding to post-ICU recovery

Precision nutrition in critical illness should be understood as a longitudinal clinical strategy rather than a fixed prescription for calorie and protein delivery. This structured narrative review used PubMed/MEDLINE as the primary database and supplemented the search through Web of Science Core Collection and Google Scholar. Publications from January 2020 to January 2026 were prioritized, while earlier landmark trials, guidelines, and consensus papers were retained when relevant. Evidence from 73 references, including guidelines, randomized trials, systematic reviews, and relevant observational or mechanistic studies, was synthesized. We propose an operational framework with bedside indicators for early acute illness, stabilization/prolonged ICU care, and post-ICU recovery. During early acute instability, safe initiation and tolerance-based progression are favored over immediate completion of calculated targets. During stabilization and recovery, greater emphasis is placed on correcting persistent deficits, preserving lean mass, and supporting rehabilitation. Feeding intolerance is interpreted as gastrointestinal dysfunction, avoidable interruption, aspiration risk, or persistent inability to sustain enteral nutrition. Post-pyloric feeding and supplemental parenteral nutrition are selective escalation strategies, with safeguards against overfeeding and metabolic complications. After ICU discharge, quantified intake, swallowing function, muscle mass, functional trajectory, and participation in rehabilitation should guide continued support. The framework contextualizes existing recommendations and requires prospective validation.