Calculation of basal metabolism and daily caloric needs according to Harris and Benedict
The Harris & Benedict equations return the amount of energy needed to sustain the basal metabolic rate and daily caloric needs. These are two mathematical formulas accepted in the medical-scientific field for almost a century, since they were elaborated back in 1919. During the last 100 years, however, the lifestyle has changed and the percentage of overweight and obese people is markedly increased (the Harris & Benedict formulas do not take into account the lean mass of the subject, which is much more metabolically active than the fat one, but of the body surface). Consequently, when applied to severely obese or rather muscular subjects, the accuracy of these formulas is rather poor.
The following calculation module, based on the formulas of Harris & Benedict, calculates the basal metabolism and the daily calorie requirement in hospitalized patients.
For men basal metabolism (BMR) =
66.5 + (13.75 x kg) + (5.003 x cm) - (6.775 x age)
For women, basal metabolism (BMR) =
655.1 + (9.563 x kg) + (1.850 x cm) - (4.676 x age)
The daily caloric requirement is equivalent to the basal metabolism multiplied by the sum of the weights given to physical activity and stress factors (from 1.2 to over the two units).
- Harris J, Benedict F. A biometric study of basal metabolism in man. Washington DC Carnegie Institute of Washington. 1919.
