Energy Adequacy of Planned Diets in Institutionalized Older Adults: A Scenario Analysis Based on Requirements from Indirect Calorimetry

<b>Background/Objectives:</b> Older adults living in long-term care facilities (LTCFs) are at high risk of undernutrition. This study evaluated the adequacy of planned energy intake (PEI) by comparing prescribed diets with individual requirements measured using indirect calorimetry (IC) and by modelling how different levels of food consumption affect energy adequacy. <b>Methods:</b> In this cross-sectional study, 169 adults aged ≥ 65 years living in LTCFs underwent anthropometric assessment and IC-based measurement of resting energy expenditure. Total energy expenditure (TEE) was derived using activity-specific PAL factors. PEI was calculated from 7-day menu records (oral diets) or enteral feeding prescriptions. Scenario analyses assumed intake levels from 100% to 50% of PEI and applied BMI-specific adequacy thresholds. <b>Results:</b> Mean TEE was 1447 ± 359 kcal/day (25 ± 6 kcal/kg), whereas mean PEI was 1999 ± 400 kcal/day, yielding an average surplus of 552 ± 496 kcal/day and a TEE/PEI ratio of 0.76. PEI did not differ across sex, BMI, or activity groups despite significant differences in measured TEE. Individuals receiving enteral nutrition demonstrated close agreement between intake and expenditure. Fewer than half of residents consumed > 75% of their served portion, about one third consumed 51-75%, and approximately one fifth consumed ≤ 50%, based on caregiver reports. Scenario modelling showed that the proportion of adults meeting adequacy criteria remained relatively stable at intake levels of 100-70% of PEI but declined significantly below 70%. <b>Conclusions:</b> Planned dietary energy provision exceeded measured requirements, yet underweight remained frequent, indicating a gap between prescribed and consumed energy. Monitoring actual intake and adjusting provision to individual needs are essential in LTCFs.