estimation of BMR and RMR

Last reviewed 01/2018

Tabulated below is a system for estimating the BMR. Units are: weight in Kg, BMR in kcal/24hr.

AGE MALE FEMALE

15-18 years 17.6 x weight + 656 13.3 x weight + 690 18-30 years 15.0 x weight + 690 14.8 x weight + 485 30-60 years 11.4 x weight + 870 8.1 x weight + 842 over 60 years 11.7 x weight + 585 9.0 x weight + 656

Devised from work by Schofield (1985).

Alternatively, the Harris-Benedict equations can be used to provide approximations of RER based on data taking into account sex, age, weight and height:

• for men = 67 + 14W + 5H - 7A
• for women = 655 + 10W + 2H - 5A

Where W is the weight in kg; H is height in cm; A is age in years. Additionally, stressors can modulate this value: Stress Multiplication factor

• intra-abdominal sepsis 1.2-1.4
• invasive sepsis 1.3-1.6
• metastatic cancer 1.1-1.3

Harris-Benedict equations tend to overestimate energy expenditure by 10-15% and lean body mass may provide a better index of RER. Nevertheless, they can be applied to work out a practically-relevant daily energy expenditure in combination with the energies of activity and diet-induced thermogenesis.