Which formula is commonly used to estimate basal metabolic rate (BMR) in adults?

• A. Mifflin-St Jeor equation.
• B. Cunningham equation.
• C. Fried's formula.
• D. Body surface area method.

Answer: (A)

Estimating resting energy expenditure helps determine how many calories a person needs at rest, which guides daily energy targets. The Mifflin-St Jeor equation is the most commonly used in adults because it was developed with modern populations and tends to be accurate across a wide range of body sizes and ages using simple inputs: weight, height, age, and sex. The formula gives two versions: for men, BMR is 10 times weight plus 6.25 times height minus 5 times age plus 5; for women, it’s the same components but minus 161 instead of plus 5. This balance of factors closely mirrors how metabolic rate changes with body size and aging, making it a standard choice in clinical and nutrition practice. Other methods, like the Cunningham equation which uses fat-free mass, can be more precise for lean individuals but require body composition data; methods based on body surface area or older, less accurate formulas don’t align as well with typical adult energy needs. That’s why Mifflin-St Jeor is the best-fitting choice for estimating BMR in adults.