Daily Estimated Energy Expenditure

Our body needs a minimum rate of energy per day in order to maintain itself at resting state, such as heart beating, breathing, keep the body temperature steady round 370, etc. This rate is called Basal Metabolic Rate (BMR).

NB! Sometimes this term may be refered as Basal Energy Expenditure (BEE). And sometimes as Resting Metabolic Rate (RMR) or Resting Energy Expenditure (REE). These terms are often used interchangeably. In short the difference between BMR and RMR is that the measurement of BMR is taken under restrictive conditions than RMR.

The estimated rate of the BMR could be done by using the Harris-Benedict equation and should be good enough for most people.

For men:
BMR (Kcal) = 66.47 + 13.75w + 5h - 6.76a

For women:
BMR (Kcal) = 655.1 + 9.56w + 1.85h - 4.68a

where
w = weight (kg)
h = height (cm)
a = age (year)

The estimating of Total Energy Expenditure (TEE), the amount of energy needed per day, is composed of three factors:

  • Basal metabolic rate (BMR)
  • Thermic Effect of Food (TEF) or Thermic Effect of a Meal (TEM)
  • Daily activity or Thermic Effect of Activity (TEA)

In short the Thermic effect of food (TEF) is the energy that is required to digest the food. For simplicity we’ll only focus on the BMR and TEA when estimating the daily energy expenditure in this post. Before estimating the daily energy expenditure, we’ll first look at Metabolic Equivalent of Task (MET) and Physical Activity Level (PAL), where MET is an expression for the energy cost of different physical activities and is defined as the ratio of the BMR, and PAL is an expression of a person’s daily physical activity as a ratio number.

The following we’ve listed a few of MET values (an extended list is located here):
Sleeping 1.0
Sitting (desk work) 1.8
Light work (cooking, washing dishes, etc.) 2.0
Walking (~4.8Km/h) 3.3
Running (~9.6Km/h) 10.0
Two examples (inactive and active day) for the daily expenditure:
Inactive day Active day
Activities Time (hour) MET x Time Time (hour) MET x Time
Sleeping 10 10 8 8
Sitting 11 19.8 8 14.4
Walking 1 3.3 3 9.9
Light work 2 4 4 8
Running 0 0 1 10
Total 24 37.1 24 50.3
The PAL values for the two examples are as follow:
PAL (inactive day) = 37.1 / 24.0
                   = 1.54

PAL (active day)  = 50.3 / 24.0
                  = 2.09

Now that we have the PAL value, we could rougly estimated the total energy expenditure per day.

TEE = PAL x BMR

Examples

--------------------
- Man
--------------------
Age:    25
Weight: 68Kg
Height: 170cm

His BMR:
66.47 + (13.75 x 68) + (5 x 170) - (6.76 x 25) = 1686Kcal/day

His TEE of an inactive day:
1.54 x 1686 = 2596Kcal/day

--------------------
- Woman
--------------------
Age:    25
Weight: 60Kg
Height: 165cm

Her BMR:
655.1 + (9.56 x 60) + (1.85 x 165) - (4.68 x 25) = 1417Kcal/day

Her TEE of an active day:
2.09 x 1417 = 2962Kcal/day

References & Links

References about this subject.
Online BMR calculator.