How Many calories do you need each day?
This is a good
question. The number of calories that you need every day just to survive is
called your maintenance level, or you Total Daily Calorie Expenditure. Just by
sitting on the couch and resting you are still burning calories. In a 24-hour
period you will burn a certain number of calories on average. This maintenance
level is where the number of calories that you burn is exactly equal is the
number of calories consumed.
A lot of researches by
exercise physiologist have come up with”average” daily calorie expenditure.
For women the average
is 2100 cal per day.
For men for men the average is 2700-2900 cal per day.
It is also important
that you understand the word ‘average’ here. These figures are estimates and
are to be used as a guide, and not as a hard and fast fact for every person in
the world. Circumstances different to each person ensure that these averages
don’t always apply to everyone.
For example: an elite
athlete could expel anywhere from 3500-5000 cal per day depending on their
training regime.
To determine the
number of calories for you personally or your TDEE, you first need to calculate
your ‘basal metabolic rate (BMR)’.
By definition, the BMR
is “The measurement of energy required to
keep the body functioning at rest”.
That means if you were
to sit on a couch for 24hrs straight, the rate at which your body burns
calories is your BMR.
The Harris Benedict
formula is one of the most accurate for this calculation, as it takes into
account many factors.
Man: BMR = 66+ (13.77
x weight in kilograms) + ( 5 x
height cms) – (6.8 x age in years)
Women: BMR = 655+ (9.6
x weight in kilograms) + ( 1.8 x
height cms) – (4.7 x age in years)
Example
Man, 25 years old, you are 5’11” tall (180 cm),
you have a 84 kg, and you have a desk job
BMR = 66 + (13.77X 84) + (5X180)-(4.7X25)
BMR = 66+ 1156.68 + 900 – 117.5
BMR = 2005.18
Now you know you’re
basal metabolic rate you can calculate your TDEE by multiplying BMR with the
following activity factor
Sedentary = BMR x1.2 (little
or no exercise)
Light activity = BMRx1.375 (light
exercise/sports – 1.3 days per week)
Mod. Active = BMRx1.55 (moderate
exercise 3-5 days per week)
Very Active = BMRx1.725 (hard
ex/sports 6-7 days per week)
Extra active = BMRx1.9 (hard
daily exercise, 2 x day training)
To continue from the
following example
BMR X Activity Level
2005.18 X 1.2 = 2406.22
What this means is
every day you need to consume 2406.22 cal in order to maintain your body fat
level. The fact that your activity level, being a desk job is taken into
account, is the reason for the slightly higher calorie needs.
Remember, your BMR
only gives you your calorie needs if you were to stay on the couch for 24hrs
straight. Given that you even have a desk job, there is still movement factors
involved, including but not limited to get to and from work, walking around the
office, using your brain to work etc etc etc.
So to reduce your
weight you need to eat fewer calories than 2406.22 and to gain weight you need
to eat more calories than 2406.22.
So why not just cut
out 500 cal? Although this would work it could send your body into starvation
mode. And as described earlier, when your body goes into starvation mode, your
metabolism decreases or slows down; therefore you would need fewer calories per
day to survive.
The best method to
work out how many calories you need to decrease your daily intake by is the
percentage method. For optimal and safe fat loss a percentage reduction of
15-20% less calories than your TDEE needs every day is optimum for a healthy
weight loss regime.
So for the above
example a safe weight loss regime would be reducing the calorie intake of 15%
of 2406.22 cal which equals 361 cal.
So our 25-year-old
male who wanted to lose body fat would reduce his calorie intake to 2045 cal
per day. This accompanied with an exercise regime later explained will be the
optimum way for him to lose weight safely.
The last part I will
say on calories is that “calorie
counting is necessary”. For you to
lose weight you must eat fewer calories than you burn safely. I can’t stress
that enough.