# Harris–Benedict equation

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The Harris–Benedict equation (also called the Harris-Benedict principle) is a method used to estimate an individual's basal metabolic rate (BMR) and daily kilocalorie requirements. The estimated BMR value is multiplied by a number that corresponds to the individuals's activity level. The resulting number is the recommended daily kilocalorie intake to maintain current body weight.

The Harris–Benedict equation may be used to assist weight loss — by reducing the kilocalorie intake to a number below the estimated maintenance intake of the equation.

## Step 1 – calculating the BMR

The original Harris–Benedict equations published in 1918 and 1919.[1][2]

 Men BMR = 66.4730 + (13.7516 x weight in kg) + (5.0033 x height in cm) – (6.7550 x age in years) Women BMR = 655.0955 + (9.5634 x weight in kg) + (1.8496 x height in cm) – (4.6756 x age in years)

The Harris–Benedict equations revised by Roza and Shizgal in 1984.[3]

 Men BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) - (5.677 x age in years) Women BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) - (4.330 x age in years)

## Step 2 – applying the Harris-Benedict Principle

The following table enables calculation of an individual's recommended daily kilocalorie intake to maintain current weight.[4]

 Little to no exercise Daily kilocalories needed = BMR x 1.2 Light exercise (1–3 days per week) Daily kilocalories needed = BMR x 1.375 Moderate exercise (3–5 days per week) Daily kilocalories needed = BMR x 1.55 Heavy exercise (6–7 days per week) Daily kilocalories needed = BMR x 1.725 Very heavy exercise (twice per day, extra heavy workouts) Daily kilocalories needed = BMR x 1.9

## Applications for weight loss

Using the formulae above, a 24-year-old, 80 kg male who is 180 cm would have a BMR of 1900. If he exercised moderately, he would multiply his BMR by his activity level (1900 x 1.55) to determine daily kilocalorie requirements, which would be 2945 kcal per day to keep his weight at 80 kg. This may seem like a high kilocalorie intake, but his activity level requires it. This individual would exercise normally but not lose weight. The same individual without the exercise routine would only be able to consume 2273 kcal per day without gaining weight. The US Department of Health and Human Services Daily Value Guidelines provides figures that support the above example.[5]

Using the Harris-Benedict Equation, individuals can take a mathematical approach to weight loss. There are 3500 kilocalories in 1 lb (0.45 kg) of body fat. Using the Harris-Benedict Principle, if someone has a daily allowance of 2500 kilocalories, but he reduces his intake to 2000, then the calculations show a one pound loss every 7 days.

## History

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”.

## Cited sources

1. ^ A Biometric Study of Human Basal Metabolism. J. Arthur Harris and Francis G. Benedict. Proceedings of the National Academy of Sciences. Vol. 4, No. 12 (December 1918): 370–373.
2. ^ A Biometric Study of Basal Metabolism in Man. J. Arthur Harris and Francis G. Benedict. Washington, DC: Carnegie Institution, 1919.
3. ^ The Harris Benedict equation reevaluated. A.M. Roza and H.M. Shizgal. American Journal of Clinical Nutrition. Vol. 40, No. 1 (July 1984): 168-182.
4. ^ Harris Benedict formula for women and men. GottaSport.com. Retrieved on 2011-10-27.
5. ^ How to Balance the Food You Eat and Your Physical Activity and Prevent Obesity. Nhlbi.nih.gov. Retrieved on 2011-10-27.