Mar 17, 2012

ENERGY VS WEIGHT - THE SCIENCE


although adopting a vegan diet can be a great way to initiate weight loss and improve your general health dramatically, it can also be just as unhealthy as a non-vegan diet without consideration of some basic facts! 

when it comes to weight loss the science demands that your energy expenditure be greater than your energy intake. pretty straight forward! if the reverse is the case, then weight gain is clearly inevitable! 

to determine your estimated energy requirement (eer) - the amount of energy you should consume per day - you can refer to the nhmrc's 'nutrient reference values for australia and new zealand' (which can be downloaded from the nhmrc's website at www.nhmrc.gov.au). the table on page 20 can be used to determine the eer based on height and weight, and an estimated BMR (basal metabolic rate*) . the bmr is then referenced against a person's physical activity level ('pal') (from 1.2 [bed rest] to 2.2 [professional athlete]) 

to identify your eer you must first measure your height (m) and weight (kg) (these measurements can also be used to determine your body mass index [bmi] - which equals weight (kg) divided by your height squared (m2).

once you have determined your height, locate this value on the first vertical column according to your age group. next to this measurement will be a weight (given in kg) based on a bmi of 22 (which falls within the acceptable/healthy range of the bmi scale). bmi does not, however, take muscle mass into consideration and has been labelled as an inaccurate measurement of true body fat mass. 

nhmrc's nutrient reference values for australia and new zealand (nhmrc, 2005)

moving horizontally across the table from the height (ensuring you are referring to the correct section based on your gender) you must now determine your physical activity level. 

i have a desk job and, although i try to make it to the gym everyday to every second day for a reasonable workout, i would therefore consider my pal to be 1.4 as the largest portion of my days involves long periods of sitting. if perhaps you hold a more active role, and were therefore required to be moving around or standing for a considerable period of your day, you may consider your pal to fall between 1.6 and 1.8 on the scale. 

the intersecting point on the table is the eer based on your height and pal. using my height and pal the table suggests that i should be consuming roughly 8,000kJ/day (1,912 kilocalories^/day - commonly referred to just as 'calories') in order to balance my energy intake with output. I would, however, like to lose some weight and can therefore use the weight column (in place of the height column) to identify an eer that would enable me to achieve this goal. 

without adjusting my pal and moving across the table from my desired weight, the table suggests my eer to be approximately 7,500kJ/day (1,793 kilocalories^/day).

as a general guide, the nhmrc's eer table is a simple and effective way to identify an eer and make recommendations of an appropriate eer for weight maintenance as well as an eer suited to promoting weight loss. it is always important to consult your doctor before making any radical changes to your diet to ensure your weight loss goals are realistic and you continue to access the required vitamins, minerals and essential nutrients without compromising your health. 

* basal metabolic rate (bmr) = the energy required in order to maintain the normal functions of your body
1 kilojoule = 0.239005736 kilocalories

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