energy requirements
Last reviewed 01/2018
The daily energy requirements of the individual are highly variable. They are dependent on numerous factors e.g.:
- age
- sex
- amount of physical activity
- stage of ovarian cycle if female
- environmental temperature
The energy input of the diet can be roughly calculated using the following algorithm; it is useful for quantifying the nutritional support needed for the hospitalized patient:
- calculate the resting metabolic rate using the Harris-Benedict equation
- estimate the stress factor dependent on the patient's disease state (see submenu)
- estimate the activity factor
- estimate the dietary factor from dietary induced thermogenesis
- multiply all of the above terms to give energy requirements in kcal/kg/day
Practically, patients with uncomplicated disease processes require around 30 kcal/kg/day. Those exceptionally stressed e.g. multiple trauma victims, extensive operation, major sepsis, may require up to 40 kcal/kg/day.