The Mifflin-St Jeor Equation
Determining how much energy the human body requires at rest is the fundamental challenge of Nutrition science. The Mifflin-St Jeor equation is the most accurate predictive tool we have today.
History and Development
Developed in 1990 by Mark D. Mifflin and colleagues, this equation was a response to the aging Harris-Benedict formula (1919). As modern lifestyles became more sedentary and body compositions changed across the population, a more refined mathematical model was needed to predict Basal Metabolic Rate (BMR).
The Mathematics of Metabolism
For Men
BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (y) + 5
For Women
BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (y) - 161
Why It Wins Over Other Formulas
Studies have shown that the Mifflin-St Jeor equation is accurate to within 10% of measured RMR in more individuals than any other non-invasive method. It effectively accounts for weight, height, and age—the critical biological markers for energy expenditure.
Calculating for Resistance Training
Individuals with high Lean Body Mass may find that this equation carries a slightly higher margin of error, as it doesn't explicitly calculate muscle-to-fat ratios. In these cases, the Katch-McArdle formula is often used as an alternative.