Having recently been asked about calorie usage, and following an unsuccessful online search for a table of PAR values, I have reproduced, below, one I had in my physiology notes from a few years ago. Using PAR allows a much more accurate calculation of TEE or PAL than the typically limited ‘activity levels’ (e.g. sedentary, lightly active, etc.) commonly seen (as well as providing some meaning/context for the PAL values).
Basal metabolic rate (BMR): The necessary energy to maintain body functions while awake, but under conditions of rest (with sufficient fasting to avoid the effects of food intake on metabolism) for an individual (typically factoring in mass, height, age, and gender).
Clinically, metabolic rate is typically determined through oxygen (O2) consumption. With each litre of oxygen consumed corresponding to approximately 4.8kcal of chemical energy liberated.
Formulas for BMR provide an estimate, the one below is the Mifflin equation:
Total energy expenditure (TEE): The average energy an individual spends in a 24-hour period (i.e. the average energy used in a typical day – may be averaged from a group instead of individually).
Physical activity level (PAL): TEE divided by BMR (for 24 hours) – expressed as a multiple of BMR. Alternatively, one can calculate a weighted average of PAR values over a ‘typical’ 24 hour period to get a reasonable estimate of PAL.
Physical activity ratio (PAR): The energy requirements for a given activity expressed as a multiple of BMR (i.e. energy spent/BMR, over the same unit of time)
PAR Values for Common Activities
|B.M.R. Multiplier (PAR)|
|Awake, lying still||1.2|
|Sitting – at rest||1.4|
|Sitting – and reading||1.7|
|Sitting – and writing or taking notes or homework||2.1|
|Sitting and eating||2.2|
|Sitting and typing (rapidly)||2.3|
|Dressing and undressing||1.8|
|Driving (a car)||2.0|
|Dishwashing, ironing, etc.||2.2|
|Cycling (for fun)||3.1|
|Vacuuming, sweeping, or cleaning house||4.0|
|Dancing (moderate speed)||5.0|
|Horseback riding (moderate speed)||7.2|
|Playing ping-pong (competitively)||17.5|
|Skating (speed skating)||18.0|
|Horseback riding (hard)||22.0|
Stairs – not based on B.M.R.:
|Walking up stairs:||0.014Cal/kg/3 steps|
|Walking down stairs:||0.004Cal/kg/3 steps|
Fat has an energy density of 9.4kcal/g – but, due to water content, adipose tissue is normally taken at about 8kcal/g – this works out to just over 3600kcal/lb or around 8000kcal/kg.
A final point of mention – the ‘calorie’ (Cal – note the capital ‘C’) used in nutrition is actually a kilocalorie (kcal – note the lowercase ‘c’): 1Cal = 1kcal= 1000cal. By definition a calorie (cal) is the amount of heat (energy) needed to raise the temperature of 1g of water by 1°C.
Thanks for the neat summary. I was just wondering what the difference is between a PAR value for a given task and the metabolic equivalent of tasks (METs)?
The values seem very similar i.e. sleeping according to PAR 1.0 vs METs 0.9 (jogging, 8.6 vs 7.0, respectively).
Both concepts are to my knowledge calculated similarily:
PAR: TEE / Basal Metabolic Rate
METs: TEE / Resting Metabolic Rate
As far as my understanding goes, the values represent essentially equivalent amounts of energy used. The difference, however, is that PAR is based on BMR – which requires a ‘more restful’ state for procurement. As such, since BMR < RMR, you will expect that PAR values are higher than MET values in order to give the same energy usage. The advantage of MET values is that it is easier to clinically measure RMR than BMR (since the conditions are less strict). Note, for instance, that PAR is based on a ‘1.0’ of sleeping, whereas MET is based on a ‘1.0’ of quiet sitting.
Thank you very much!
I notice that the mifflin equation here is for BMR but the wikipedia site ref link to the abstract indicates REE in the title – do REE and RMR differ, are REE and BMR the same thing? I am a bit confused
REE and BMR are extremely similar, but not identical. Essentially, REE is BMR taken under slightly less stringent conditions – its definition is very similar to RMR. You will note however, that the original article by Mifflin, et. al. (Am J Clin Nutr February 1990 vol. 51 no. 2 241-247) says ‘The most widely used predictive equations for REE were developed on 136 men and 103 women by Harris and Benedict ~70 y ago”. The Harris & Benedict equation is used for calculating BMR, suggesting that Mifflin et. al intended their equation to be an improvement upon the calculation for BMR – however looking over the conditions of the test suggests it was taken as RMR. As per the protocol for measuring REE, the BMR is defined as REE measured directly after waking up in the morning, and the BMR and REE values differ by less than 10%, making them interchangeable. I’ll leave it up to you to decide the intent of the Mifflin equation. The numbers used in the chart, however, are for BMR, not RMR, although the difference will be fairly small.