Harris-Benedict equation
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 calorie requirements.[1] The estimated BMR value is multiplied by a number that corresponds to the individuals's activity level. The resulting number is the recommended daily calorie intake to maintain current body weight. The equation assumes a normal body composition, with an average ratio of muscle mass to fat mass, so it may be inaccurate for individuals who are very muscular (the formula underestimates true requirements) or for individuals who are very fat (the equation overestimates true requirements).[2]
The Harris-Benedict equation may be used to assist weight loss — by reducing the calorie intake to a number below the estimated maintenance intake of the equation.
Contents |
[edit] Step 1 – calculating the BMR
The following table enables calculation of an individuals Basal Metabolic Rate (BMR).
| BMR calculation for men | BMR = 66.5 + ( 13.75 x weight in kg ) + ( 5.003 x height in cm ) – ( 6.755 x age in years ) |
| BMR calculation for men | BMR = 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) – ( 6.76 x age in years ) |
| BMR calculation for women | BMR = 655.1 + ( 9.563 x weight in kg ) + ( 1.850 x height in cm ) – ( 4.676 x age in years ) |
| BMR calculation for women | BMR = 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches ) – ( 4.7 x age in years ) |
[edit] Step 2 – applying the Harris-Benedict Principle
The following table enables calculation of an individual's recommended daily calorie intake to maintain current weight:
| Little to no exercise | Daily calories needed = BMR x 1.2 |
| Light exercise (1–3 days per week) | Daily calories needed = BMR x 1.375 |
| Moderate exercise (3–5 days per week) | Daily calories needed = BMR x 1.55 |
| Heavy exercise (6–7 days per week) | Daily calories needed = BMR x 1.725 |
| Very heavy exercise (twice per day, extra heavy workouts) | Daily calories needed = BMR x 1.9 |
[edit] 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 calorie requirements, which would be 2945 kcal per day to keep his weight at 80 kg. This may seem like a high calorie 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.[3]
Using the Harris-Benedict Equation, individuals can take a mathematical approach to weight loss. There are 3500 calories in 1 lb (0.45 kg) of body fat. Using the Harris-Benedict Principle, if someone has a daily allowance of 2500 calories, but he reduces his intake to 2000, then the calculations show a 1 pound loss every 7 days.
[edit] 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”.
[edit] See also
[edit] Cited sources
- ^ Daily Calorie Needs – Harris Benedict Equation. multivitamin.co.uk
- ^ Harris Benedict formula for women and men. GottaSport.com. Retrieved on 2011-10-27.
- ^ How to Balance the Food You Eat and Your Physical Activity and Prevent Obesity. Nhlbi.nih.gov. Retrieved on 2011-10-27.
