Why do BMR formulas disagree?

Different formulas were derived using different populations. For instance, Cunningham was derived from athletic individuals with higher muscle mass, while Mifflin studied a broader demographic cross-section.

Calories & BMR

BMR Comparison Calculator

Compare Mifflin-St Jeor, Harris-Benedict, Katch-McArdle, and Cunningham side-by-side

Input Parameters

Real-time calculation updates dynamically as you adjust inputs. Values remain strictly local on your device.

Consensus Average BMR4-Formula Consensus

1770kcal/day

Average across Mifflin, Harris-Benedict, Katch-McArdle, and Cunningham

Formula	BMR / RMR	Target Cohort	Primary Input Focus
Mifflin-St Jeor (1990)	1699 kcal	General Population	Total Weight, Height, Age
Revised Harris-Benedict (1984)	1763 kcal	Clinical Standard	Total Weight, Height, Age
Katch-McArdle (1983)	1731 kcal	Athletic Individuals	Fat-Free Lean Mass
Cunningham (1980)	1886 kcal	Strength & Power Athletes	Fat-Free Lean Mass

Clinical Responsibility Note: This calculation provides statistical estimations for informational and educational purposes only. It is not an individualized medical diagnosis or clinical prescription.

Mathematical Formula & Scientific Methodology

Formula: Multi-Formula Comparative Engine

Compares Mifflin-St Jeor, Harris-Benedict, Katch-McArdle, and Cunningham

Demonstrates variance between total-mass equations and lean-mass equations.

Model Assumptions

Adult subjects

Variables & Standard Units

Symbol	Physiological Meaning	Unit
Consensus	Arithmetic mean across validated biometric equations	dimensionless

Scientific Limitations

Differences can span 100-200 kcal depending on personal muscularity

Peer-Reviewed Scientific Citations

A new predictive equation for resting energy expenditure in healthy individuals (1990)

Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990) — The American Journal of Clinical Nutrition, 51(2), 241-247

Key Finding: Mifflin-St Jeor equation is accurate within ±10% of measured REE in non-obese and obese individuals, recommended by the Academy of Nutrition and Dietetics as the most reliable standard equation.

A reanalysis of the factors influencing basal metabolic rate in normal adults: importance of fat-free mass (1980)

Cunningham JJ (1980) — The American Journal of Clinical Nutrition, 33(11), 2372-2374

Key Finding: Demonstrated that lean body mass accounts for nearly all variance in basal metabolic rate between sexes and ages.

Nutrition, Weight Control, and Exercise (1983)

Katch FI, McArdle WD (1983) — Lea & Febiger, Philadelphia

Key Finding: BMR equation derived directly from Fat-Free Mass (FFM), providing superior accuracy for athletes with known body fat percentage.

Frequently Asked Questions

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