didjeridude
29-May-06, 03:57pm
So there seems to be a pretty regular question about how to measure %bodyfat so I thought I'd start a dedicated thread on it.
Gold Standards:
Hydrodensiometry = underwater weighing
Dual X-Ray absorbiometry = DXA
Doubly labelled water
These three methods are rare, expensive and require considerable technical expertise. Its pretty unlikely you'll ever come acorss these techniques unless you're involved in a research study.
Next best option:
Skinfold thickness = the "pinch" test
There are two ways to go about this: the better way is to have your skinfolds measured by an ISAK accredited (http://www.isakonline.com/) anthropometrist who is using a properly calibrated set of harpenden skinfold calipers. The povo option is to have it done by a non-accredited local gym trainer using those cheap, plastic calipers.
Either way, the sum of skinfolds can only ever be an ESTIMATION of %bf. It will give a rough figure only with a range of around 7-10% accuracy (eg: your true value is 14% but depending on which conversion equation is used you could get a value anywhere between 7 and 21% bf). However if you want to track progress over time, then the sum of the skinfolds themselves is a far more reliable figure. Usually the sum of 7 skinfolds (units = mm) is best and the most common. As opposed to an error of 7-10% for %bf, the sum of 7 figure should have an error of about 2-3% in capable hands.
Since it is fast, cheap and reliable, the sum of 7 is the standard that we use in the elite sport system around Australia for monitoring of athletes.
A benchmark for women is about 80mm, and below 60mm you'll definately be looking cut if you have any muscle tone whatsoever. In men a benchmark of 60mm is a bare minimum and below 40mm you'll be looking pretty buff. A change of any more than 4-5mm represents a "real change" whereas anything less is just error of measurement.
Least desirable option:
Bioimpedance = those scales that you stand on which just spit out a number.
This method is dependent on hydration status so unless you get this checked first there will be a large source of error. I've used these devices and gotten values 4-5% different from what I got 3mins earlier. If you have to use this option, the best approach is to have it done first thing in the morning on an empty stomach with a standard amount of fluid ingestion upon waking. Have the test done 4 or 5 times and take the average score.
Cheapest method but a goodie:
Look in the mirror.
Gold Standards:
Hydrodensiometry = underwater weighing
Dual X-Ray absorbiometry = DXA
Doubly labelled water
These three methods are rare, expensive and require considerable technical expertise. Its pretty unlikely you'll ever come acorss these techniques unless you're involved in a research study.
Next best option:
Skinfold thickness = the "pinch" test
There are two ways to go about this: the better way is to have your skinfolds measured by an ISAK accredited (http://www.isakonline.com/) anthropometrist who is using a properly calibrated set of harpenden skinfold calipers. The povo option is to have it done by a non-accredited local gym trainer using those cheap, plastic calipers.
Either way, the sum of skinfolds can only ever be an ESTIMATION of %bf. It will give a rough figure only with a range of around 7-10% accuracy (eg: your true value is 14% but depending on which conversion equation is used you could get a value anywhere between 7 and 21% bf). However if you want to track progress over time, then the sum of the skinfolds themselves is a far more reliable figure. Usually the sum of 7 skinfolds (units = mm) is best and the most common. As opposed to an error of 7-10% for %bf, the sum of 7 figure should have an error of about 2-3% in capable hands.
Since it is fast, cheap and reliable, the sum of 7 is the standard that we use in the elite sport system around Australia for monitoring of athletes.
A benchmark for women is about 80mm, and below 60mm you'll definately be looking cut if you have any muscle tone whatsoever. In men a benchmark of 60mm is a bare minimum and below 40mm you'll be looking pretty buff. A change of any more than 4-5mm represents a "real change" whereas anything less is just error of measurement.
Least desirable option:
Bioimpedance = those scales that you stand on which just spit out a number.
This method is dependent on hydration status so unless you get this checked first there will be a large source of error. I've used these devices and gotten values 4-5% different from what I got 3mins earlier. If you have to use this option, the best approach is to have it done first thing in the morning on an empty stomach with a standard amount of fluid ingestion upon waking. Have the test done 4 or 5 times and take the average score.
Cheapest method but a goodie:
Look in the mirror.