Mifflin–St Jeor Resting Energy Expenditure: Clinical Guide

Overview

Estimates resting energy expenditure from weight, height, age and sex using the Mifflin–St Jeor equation.

Clinical Significance

The equation estimates resting energy expenditure in adults. Total energy needs require an appropriate activity and clinical-stress assessment, and indirect calorimetry is preferred when precision is important.

When to Use

• Estimate resting energy expenditure in adults when indirect calorimetry is unavailable.
• Use measured current weight and height when clinically appropriate.
• Apply activity or stress factors only through a separate, justified plan.

How It Is Calculated

• Men: 10W + 6.25H − 5A + 5. Women: 10W + 6.25H − 5A − 161.
• The calculator validates the required inputs before applying the equation and rounds only the displayed result.

Interpretation

• The equation estimates resting energy expenditure in adults. Total energy needs require an appropriate activity and clinical-stress assessment, and indirect calorimetry is preferred when precision is important.
• Review the component values and assumptions as well as the final result.

Worked Example

Enter clinically plausible values in the stated units. MedicalC applies: Men: 10W + 6.25H − 5A + 5. Women: 10W + 6.25H − 5A − 161. Review the displayed result against the source data and the relevant clinical pathway.

Patient Considerations

• Confirm that the patient and clinical setting match the population or physiologic assumptions behind the equation.
• Consider whether treatment, organ function, pregnancy, body composition, sampling conditions or acute illness materially alter interpretation.
• Use serial calculations only when methods and units remain comparable.

Limitations

• Prediction error can be substantial in critical illness, oedema, amputation, extreme body size and pregnancy.
• It estimates resting, not total, energy expenditure.
• Body composition and ethnicity are not directly represented.

Clinical Pearls

• Do not automatically multiply by large stress factors.
• Reassess after major weight or clinical changes.
• Use indirect calorimetry when available in complex critical-care nutrition.

Common Mistakes

• Entering height in metres rather than centimetres.
• Treating REE as the final calorie prescription.
• Using an unreliable oedematous body weight without adjustment.

Evidence Base

The implementation uses the published or established relationship: Men: 10W + 6.25H − 5A + 5. Women: 10W + 6.25H − 5A − 161. The cited source should be reviewed alongside current specialty guidance before clinical deployment.

References

1. Mifflin MD, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990. — Primary publication, authoritative guideline or recognised clinical source supporting the calculation.