Question:

What is the best way to calculate RMR?

– Mark B.

Answer:

The best measurement of resting (awake/alert) metabolic rate is to conduct an indirect calorimetry test using metabolic equipment, as done in a research laboratory or hospital setting. In lieu of a physical test, the second best way to predict resting metabolic rate is to calculate/estimate using a validated equation. I recommend the Mifflin-St. Jeor equation or the one used by the World Health Organization. For your computational pleasure here they are:

The Mifflin St. Jeor equations are used often in the medical and weight loss fields because of their accuracy, and are recommended by the Academy of Nutrition and Dietetics.

• Women:          (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) – 161

• Men:                (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) + 5

The World Health Organization, as well as the United Nations University and Food and Agricultural Organization, use the following equations, which were derived based off a large database, reflecting many countries over several decades.

• 18-30 yrs:        kcal/d = 13.3 × weight (kg) + 334 × height (m) + 35
• 30-60 yrs:        kcal/d = 8.7 × weight (kg) – 25 × height (m) + 865
• >60 yrs:           kcal/d = 9.2 × weight (kg) + 637 × height (m) – 302

As is true with any equation, these equations are only estimations of your needs, so you might want to try both and obtain a range that your true RMR probably falls within. Neither of the above take into consideration lean mass versus fat mass, so they aren’t practical for extremely muscled or morbidly obese individuals. For teens, the Schofield method (previously used by the World Health Organization and the US government to formulate the RDAs) has different equations for various age groups.

– Debbie J., MS, RD