My wonderful trainer put together the following information which I found to be very valuable and thought I would share it.
Firstly you need to work out your BMR (Basal Metabolic Rate), this is the energy your body uses in a state of rest to 'maintain' your current bodyweight/composition.
How do know what your BMR is? Follow this formula:
Females: BMR = 655 + ( 9.6 x weight in kilos ) + ( 1.8 x height in cm ) - ( 4.7 x age in years )
Males: BMR = 66 + ( 13.7 x weight in kilos ) + ( 5 x height in cm ) - ( 6.8 x age in years )
EXAMPLE: I am currently 80.4kg and 173cm tall and 35 years of age.
655 + (9.6 X 80.4) + (1.8 X 173) - (4.7 X 35)
655 + 771.84 + 311.4 – 164.5
BMR = 1573.74 calories needed per day (at rest) to 'maintain'.
So how many calories are needed to lose a kilo?
It takes a '7000' calorie deficit. So that means once you have taken into account your BMR and calculated roughly how much energy you expend through activity you would then reduce that figure by 7000 per week and you will in theory lose a kilo.
The following enables calculation of an individuals recommended daily calorie intake to maintain current weight:
Little to no exercise - Daily calories needed = BMR x 1.2
Light exercise (1-3 days per week) - Daily calories needed = BMR x 1.375
Moderate exercise (3-5 days per week) - Daily calories needed = BMR x 1.55
Heavy exercise (6-7 days per week) - Daily calories needed = BMR x 1.725
Very heavy exercise (twice per day, extra heavy workouts) - Daily calories needed = BMR x 1.9
NOTE: You need to be honest with yourself when using this equation otherwise you will end up consuming too many calories and hence instead of being in a calorie deficit at the end of the week you will be in excess which is not what you want.
EXAMPLE: My PAL is Moderate 3 - 5 days per week
BMR 1573.74 X PAL 1.55 = 2439.97 calories needed per day (at current exercise rate) to 'maintain'
Calculation for 1kg per week loss
2439.97 x 7 (days in a week) = 17,079.79 calories needed per week
17,079.79 – 7000 (calorie deficit for 1kg) = 10,079.79
10,079.79 / 7 days = 1439.97 daily intake to achieve 1kg loss per week, exercising 3-5 times per week.
IF, however you only want to loose .5kg per week the deficit would be 3500 calories
2439.97 x 7 (days in a week) = 17,079.79 calories needed per week
17,079.79 - 3500 (calorie deficit for .5kg) = 13, 579.79
13579.79 / 7 days =1939.97 daily intake to achieve a .5 kg loss per week, exercising 3-5 times per week
It goes without saying that if you exercise more you loose more and vice-a-versa.
It is important to remember that these figures are Total Intake (including exercise to lose weight), so don’t get confused and think you need to allow for exercise.
Also don't forget that as weight changes (be it up or down) the equation will need to be recalculated.
Remember that in order to maintain vital lean muscle mass you need to loose weight at a sensible pace. Too few calories will cause muscles to degenerate and the body will store excess body fat which is No Good AND too many calories in and not enough energy out (exercise) will result in weight gain which again means more body fat.
Hope that this has been helpful...
