Your Total Daily Energy Expenditure (TDEE) is how many calories you are using on a day to day basis in order just to function and perform all the tasks placed upon your body.
This falls into two categories:
- Basal metabolic rate (how many calories your body uses just to function when doing nothing, such as energy for breathing and pumping your heart and powering your metabolism etc)
- Physical activity ratio (Do you sit around or are you up on your feet all day for example)
The two categories are then used to calculate your average TDEE
Basal metabolic rate (BMR)
We’ll use the Mifflin-St Jeor formula to estimate Basal Metabolic Rate (BMR). This is essentially the amount of energy expended per day before we add in activity levels.
There are several equations we can use but a study by the ADA (American Dietetic Association) found the Mifflin-St Jeor method to be pretty accurate. Here is the formula:
Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5
Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161.
Next we need to factor in your general day to day activity levels.
Physical activity ratio (PAR)
Now that we’ve worked out the BMR, we need to multiply it by a Physical Activity Ratio (the estimated cost of activity he does per day).
If you were working this out, you would need to multiply your BMR by:
1.2 if you do little or no exercise
1.4 if you do exercise a couple of times per week
1.5 to 1.7 if you exercise several times per week
1.9+ if you exercise every day or have a hard, physical job
Once you have figured out your BMR and PAR you will have what is known as your total daily energy expenditure (TDEE).
He’s a 30 year old male, weighing 80kg at 180cm and he never works out. He has a desk job and he wants to know his TDEE for fat loss.
So for Geoff, our 30 year old male, weighing 80kg at 180cm. His BMR would roughly be: (10 x 80) + (6.25 x 180) – (5 x 30) + 5 = 1780.
Geoff does no training or physical activity per week so we’ll multiply his BMR (1780) by 1.2. This gives us his estimated TDEE of: 2136.
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