Mapping Resting Energy Expenditure in Malnourished Children During Nutritional Rehabilitation: A Scoping Review

Nutritional rehabilitation in children with complicated acute malnutrition involves dynamic shifts in resting energy expenditure (REE), yet directly measured REE data remain limited and variable. The aim was to map and characterize evidence on REE measured by indirect calorimetry (IC) in children under 5 years requiring nutritional rehabilitation following resolution of acute illness in resource-limited settings. PubMed, Embase, Scopus, and CINAHL were searched, and ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform were screened. Studies were systematically screened and appraised using design-specific Joanna Briggs Institute tools. Extracted data included malnutrition terminology, IC measurement conditions and technique, energy expenditure (EE) metrics and units, rehabilitation phases, energy intake, and body-composition assessment. Twenty studies were included, spanning more than a century and largely comprising small inpatient cohorts. Thirteen studies (65%) reported basal metabolic rate (BMR) as the primary outcome, 4 reported REE (20%), and 2 reported total EE (10%). Seventeen studies (85%) expressed EE as weight-normalized values (kcal/kg/day). BMR ranged approximately from 20 to 70 kcal/kg/day in poststabilization, 30-70 in growth surge, and 40-75 in recovery. REE values overlapped with BMR but extended to approximately 80-85 kcal/kg/day across phases. Rehabilitation phase was identified in 19 studies. Concurrent energy intake was reported in 11 studies (55%), and body-composition assessment in 6 studies (30%). Nearly all studies were conducted in hospital-based settings (95%), with 1 study representing home-based nutritional rehabilitation. These findings delineate important interpretive boundaries by showing that apparent differences in REE across poststabilization, growth surge, and recovery phases reflect methodological and contextual variation as much as metabolic change. Harmonized longitudinal protocols that report unscaled REE alongside energy intake and body-composition measures-particularly in outpatient settings-are needed to inform physiologically grounded approaches to catch-up growth and sustained recovery.