The Harris–Benedict equation (also called the Harris-Benedict principle) is a method used to estimate an individual's basal metabolic rate (BMR).
The estimated BMR value may be multiplied by a number that corresponds to the individual's activity level; the resulting number is the approximate daily kilocalorie intake to maintain current body weight.
The Harris–Benedict equation may be used to assist weight loss — by reducing kilocalorie intake number below the estimated maintenance intake of the equation.
Step 1 – Calculating the Harris–Benedict BMR
|BMR calculation for men (metric)||BMR = 66.5 + ( 13.75 × weight in kg ) + ( 5.003 × height in cm ) – ( 6.755 × age in years )|
|BMR calculation for men (imperial)||BMR = 66 + ( 6.2 × weight in pounds ) + ( 12.7 × height in inches ) – ( 6.76 × age in years )|
|BMR calculation for women (metric)||BMR = 655.1 + ( 9.563 × weight in kg ) + ( 1.850 × height in cm ) – ( 4.676 × age in years )|
|BMR calculation for women (imperial)||BMR = 655.1 + ( 4.35 × weight in pounds ) + ( 4.7 × height in inches ) - ( 4.7 × age in years )|
The Harris–Benedict equations revised by Roza and Shizgal in 1984.
|Men||BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) - (5.677 × age in years)|
|Women||BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) - (4.330 × age in years)|
The 95% confidence range for men is ±213.0 kcal/day, and ±201.0 kcal/day for women.
|Men||BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5|
|Women||BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161|
Step 2 – Determine Total Intake
While the original paper does not attempt to translate BMR into total energy expenditure (TEE), a BMR result may be multiplied by a factor that approximates an individual's physical activity level (PAL) to estimate their TEE. The following table enables approximation of an individual's daily TEE based on some example lifestyles.
|Sedentary or light activity||Office worker getting little or no exercise||1.53||BMR x 1.53|
|Active or moderately active||Construction worker or person running one hour daily||1.76||BMR x 1.76|
|Vigorously active||Agricultural worker (non mechanized) or person swimming two hours daily||2.25||BMR x 2.25|
The Harris–Benedict equation sprang from a study by James Arthur Harris and Francis Gano Benedict, which was published in 1919 by the Carnegie Institution of Washington in the monograph A Biometric Study Of Basal Metabolism In Man. A 1984 revision improved its accuracy. Mifflin et al. published an equation more predictive for modern lifestyles in 1990. Later work produced BMR estimators that accounted for lean body mass.
Issues in dietary use
As the BMR equations do not attempt to take into account body composition, identical results can be calculated for a very muscular person, and a very fat person, who are both the same height, weight, age and gender. As muscle and fat require differing amounts of calories to maintain, the TEE estimates will not be accurate for such cases.
The paper behind the latest update (Mifflin et al) to the BMR formula states all participants in their study fall within the 'normal' and 'overweight' body mass index (BMI) categories, and so the results also do not necessarily apply to those in the 'underweight' or 'obese' BMI categories.
- Harris JA, Benedict FG (1918). "A Biometric Study of Human Basal Metabolism". Proceedings of the National Academy of Sciences of the United States of America. 4 (12): 370–3. doi:10.1073/pnas.4.12.370. PMC 1091498. PMID 16576330.
- A Biometric Study of Basal Metabolism in Man. J. Arthur Harris and Francis G. Benedict. Washington, DC: Carnegie Institution, 1919.
- Roza AM, Shizgal HM (1984). "The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass". The American Journal of Clinical Nutrition. 40 (1): 168–82. PMID 6741850.
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). "A new predictive equation for resting energy expenditure in healthy individuals". The American Journal of Clinical Nutrition. 51 (2): 241–7. PMID 2305711.
- FAO; WHO; UNU (24 October 2001). "Human energy requirements: Energy Requirement of Adults". www.fao.org. Retrieved 11 February 2018.