Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990 Feb;51(2):241-7. PMID: 2305711
Weir Energy Expenditure Calculator
Version 1.0.1
VO₂ and VCO₂ units
Urinary nitrogen correction
Energy expenditure
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kcal/day
Energy expenditure
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kJ/day
Respiratory exchange ratio (RER)
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VCO₂ ÷ VO₂
No clinical values are intentionally saved by this control.
Equations
Weir equation with urinary nitrogen correction
EE (kcal/day) = [3.941 × VO₂ (L/min) + 1.106 × VCO₂ (L/min)] × 1440 − 2.17 × N (g/day)Variables: EE = Energy expenditure (kcal/day); VO₂ = Oxygen consumption (L/min); VCO₂ = Carbon dioxide production (L/min); N = Urinary nitrogen excretion (g/day). The implemented urinary nitrogen coefficient is 2.17, the conventional rounded clinical form of the Weir correction. When VO₂ and VCO₂ are entered in mL/min, the calculator converts them to L/min before applying the equation.
Abbreviated Weir equation
EE (kcal/day) = [3.941 × VO₂ (L/min) + 1.106 × VCO₂ (L/min)] × 1440Variables: EE = Energy expenditure (kcal/day); VO₂ = Oxygen consumption (L/min); VCO₂ = Carbon dioxide production (L/min). This is used when urinary nitrogen correction is set to Ignore.
Respiratory exchange ratio
RER = VCO₂ ÷ VO₂Variables: RER = Respiratory exchange ratio (dimensionless); VO₂ = Oxygen consumption (same flow unit as VCO₂); VCO₂ = Carbon dioxide production (same flow unit as VO₂).
Energy unit conversion
EE (kJ/day) = EE (kcal/day) × 4.184Variables: EE = Energy expenditure (kcal/day or kJ/day as shown).
References
- Weir JB de V. New methods for calculating metabolic rate with special reference to protein metabolism. J Physiol. 1949;109(1-2):1-9. PMID: 15394301 DOI: 10.1113/jphysiol.1949.sp004363
- Ferrannini E. The theoretical bases of indirect calorimetry: a review. Metabolism. 1988;37(3):287-301. PMID: 3278194 DOI: 10.1016/0026-0495(88)90110-2
- Haugen HA, Chan LN, Li F. Indirect calorimetry: a practical guide for clinicians. Nutr Clin Pract. 2007;22(4):377-388. PMID: 17644692 DOI: 10.1177/0115426507022004377
- Singer P, Reintam Blaser A, Berger MM, et al. ESPEN practical and partially revised guideline: Clinical nutrition in the intensive care unit. Clin Nutr. 2023;42(9):1671-1689. PMID: 37517372 DOI: 10.1016/j.clnu.2023.07.011