Research perspective · 11 September 2026
Where 25 kcal/kg/day is described as a minimum
Clinical intake guidance and measured resting metabolism offer distinct reference points for EPK.
The minimum is explicitly stated
Recommendation 15 in the 2021 ESPEN hospital-nutrition guideline sets 25 kcal/kg actual body weight/day as the minimum energy provision for its standard diet. Its commentary describes this diet mainly for younger, short-stay patients without disease-related metabolic stress. The higher-energy hospital diet is intended for older or nutritionally vulnerable patients and provides 30 kcal/kg/day [1].
This is a context-specific nutrition recommendation, graded as a good-practice consensus point. It establishes a precedent for expressing dietary provision relative to body mass; it does not validate a diagnostic boundary for every person.
Resting expenditure is a different measurement
A 2024 study measured RMR in 324 young adults. Mean RMR per kilogram was 26.1 kcal/day in men and 24.6 in women [2]. These are observed group averages, not lower intake limits. Resting expenditure, dietary intake and total daily expenditure share energy units but describe different quantities.
For a hypothetical 70 kg person, 25 kcal/kg/day equals 1,750 kcal/day. If that is their measured resting expenditure, activity and food processing still contribute to their total needs. If it is a clinical intake estimate, it must be interpreted within that recommendation’s population and purpose.
A basal reference near 25
SACN’s 2011 report uses example basal rates for reference women and men aged 30–60 that convert to approximately 22.9 and 23.9 kcal/kg/day [4]. These daily values are calculated from the report’s per-minute rates: 0.0159 and 0.0166 multiplied by 1,440. They place a familiar adult basal scale near 25, but do not establish a universal minimum or an individual intake prescription.
The infant values in SACN Table 14 include total expenditure and energy deposited in growth. They cannot be joined to adult basal values and interpreted as a single resting-metabolism trajectory.
Meeting a minimum may not preserve function
An observational head-and-neck cancer study found that meeting the 25 kcal/kg/day reference did not adequately protect skeletal muscle; higher intake was associated with better preservation [3]. Disease and treatment limit application to healthy adults, and the association does not establish an optimal causal threshold.
A test for the EPK framework
Papers 1, 4 and 5 can use this distinction to separate intake provision, resting physiology and functional outcomes. A prospective study could examine intake per kilogram and measured RMR per kilogram together, with protein intake, body composition, activity and disease status recorded. Test thresholds against outcomes rather than importing them unchanged from a hospital population.
Dividing dietary EPK by RMR/kg cancels body mass: (intake/kg) ÷ (RMR/kg) = intake/RMR. That comparison may be useful, but it is an intake-to-resting-expenditure ratio, not a new independent body-mass measure. It also does not account fully for total expenditure.
Research and guidance
Explore more studies in the research library.
- Thibault et al. ESPEN guideline on hospital nutrition (2021), recommendation 15.
- Zhou et al. Multiple factor assessment for determining resting metabolic rate in young adults (2024).
- McCurdy et al. Meeting Minimum ESPEN Energy Recommendations Is Not Enough to Maintain Muscle Mass in Head and Neck Cancer Patients (2019).
- SACN (2011). Dietary Reference Values for Energy, Table 24 footnote (printed p.118) and Table 14.
Related working papers
Read the relevant PDFs: EPK–001 to 007 are the revised version 1.2 papers; EPK–008 to 010 are version 1.0 supplements. Earlier PDFs and DOI records remain on the paper archive.