How many kilojoules do you need…A rough estimation…
Your basal metabolic rate (BMR) refers to the minimum amount of kilojoules (i.e. units of energy) that your body requires to maintain basic bodily functions (at rest) over a 24-hour period. Your BMR is influenced by gender; body mass, activity level and age.
One of the more recent formulas for predicting BMR was published in the 2005 Dietary Guidelines. It’s not 100% accurate but it may give you a rough idea….
Here it is…
For Men
BMR = 293 – (3.8 x age) + (456.4 x height in metres) + (10.12 x weight in kgs)
For Women
BMR = 247 – (2.67 x age) + (401.5 * height in metres) + (8.6 x weight in kgs)
For example: A 41 year old female who weighs 64 kg and is 1.75 meters tall.
BMR = 247 – (2.67 x 41) + (401.5 x 1.75) + (8.6 x 64)
Her BMR = 1390.56 calories/day x 4.25 (to get from calories/kilocalories to kilojoules) = 5909.88kJ
However, BMR is the amount of energy required to maintain very basic bodily functions – such as breathing, organ functioning, etc. The activity level of an individual, however, directly affects metabolic demand and thus this factor needs to be built into the equation….
So here is the next part of the formula: Multiply your results from the above equation by the number in the left-hand column that best describes your daily activity level:
|
Activity Level Factor |
Activity Level |
|
1.0 |
Sedentary (super coach potato) |
|
1.2 |
Very light activity (nothing physical at all—a desk job) |
|
1.4 |
Light activity (you perform some activity during the day, such as walking lightly, but mainly still a non-physical job - you work out twice a week - not intensely) |
|
1.6 |
Moderate activity (still non-physical, but you do some activity during the day PLUS you work out daily -moderate intensity) |
|
1.8 |
High activity (a physical job, such a trade – plumbing/ woodwork/ landscaping, plus your training - which is fairly hard) |
|
2.0 |
Extreme activity (very physical job and very hard training) |
For Example: Let us refer back to the previous example: If this same female trains hard 5 times per week, she could be placed in the moderate category. Thus you would multiply her BMR value from the first equation above by 1.6.
1390.56 * 1.6 = 2224.89 calories per day or 9455.8 kJ/ day (Multiply the calories by 4.25 to get kilojoules)
This woman would therefore require 9455.8 kJ/day to maintain her weight. To build more muscle, she would therefore need to increase energy intake (eat more). Conversely to lose fat she would need to reduce energy intake (eat less) and / or increase energy expenditure (exercise for longer or more frequently).
Note that to reduce bodyfat safely and effectively and keep it off – you should aim to lose approximately 0.5kgs per week.
These formulas are by no means conclusive – but they will give you a rough guide…
With special thanks to:
Chris Mohr, PhD, exercise physiology, and registered dietitian.
2005 Dietary Guidelines.
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