Dexa Scan For Fat Percentage Not Bone Density

robblok · October 20, 2012

As i am pretty serious about my health and constantly trying to improve on my shape id like to keep track of my progress.

A friend of mine has had a DEXA scan done in Australia to check his fat percentage.

Its almost the best you can do, i don't want any information about those fat percentage things at gyms, they are not accurate. I have a fat caliper but its hard to really use it. So if available i would go here once every 3 months or so.

So if anyone has any information please let me know.

Tolley · October 20, 2012

I did the bio impedience test a few years back maybe that is an option if you can't get the dexa here. I just copied this info from this website http://www.dh.org/body.cfm?id=1023

How Does BIA Work?

This non-invasive test simply involves the placement of two electrodes on the person's right hand and right foot. A low level, imperceptible electrical current is sent through the body. The flow of the current is affected by the amount of water in the body. The device measures how this signal is impeded through different types of tissue. Tissues that contain large amounts of fluid and electrolytes, such as blood, have high conductivity, but fat and bone slow the signal down. As BIA determines the resistance to flow of the current as it passes through the body, it provides estimates of body water from which body fat is calculated using selected equations.

For nutritionists providing dietary supplementation and individualized nutritional guidance, BIA helps to measure progress. For individuals using BIA, an improving or healthy BIA measurement can increase the likelihood that your body is functioning properly, aging well with a reduced risk of illness.

How accurate is it?

While no methods of body composition measurement are 100% accurate, the margin of error derived from BIA is 3-4%, comparable to the skinfold caliper method. The error margin for hydrostatic weighing and the "bod pod" is 2-2.5%. Near infrared method of body composition measurement has a 4-5% margin of error. The nutritionists of Healthy Directions choose BIA over other body fat methods due to the health information provided by BIA in addition to body composition. Participants of any of the programs offered by Healthy Directions are advised to continue with one method of body composition measurement, since the progress seen from each measurement is accurate.

Very important that you are probably hydrated for this test.

robblok · October 20, 2012

Maybe with a good unit, but the units you see in gyms and such they are really not that accurate. I even have a hand held device at home. I don't use it anymore.

Problem is with this method if your real muscular then the reading is often off. Because they compare the readings with samples of the general public. That is why a dexa scan or bodypod ore even fat caliper are better for muscular people.

I consider myself muscular, its a fair description of me, not pro bodybuilder or anything like that. But muscular all the same.

Tolley · October 20, 2012

Maybe with a good unit, but the units you see in gyms and such they are really not that accurate. I even have a hand held device at home. I don't use it anymore.

Problem is with this method if your real muscular then the reading is often off. Because they compare the readings with samples of the general public. That is why a dexa scan or bodypod ore even fat caliper are better for muscular people.

I consider myself muscular, its a fair description of me, not pro bodybuilder or anything like that. But muscular all the same.

You might be right but I am not sure. The equations they use i suppose is the issue here. How are these calculated and what effect do they have.

Here is my readings from a few years back. I was a bit fatter than I am now.

Body Composition.

Ideal Weight : 75 kg

Actual weight: 85 kg

Frame Size: Medium

Skeletal tissue 9.02 Kg

Fat Mass

Fat 18kg

Ideal fat mass 14kg

Active tissue mass

ATM 43 kg

Ideal 36.85

Calories required to maintain 2089...protein 152g Carbs 203g,Fat 68g

Basal Metabolic Rate 1832.61

So according to their stats I was carrying 4kg too much fat and 7kg too much muscle.

Edited October 20, 2012 by Tolley

robblok · October 20, 2012

Tolley, its just what i have read about these tests. Could be that i am wrong but as i understand it they look up the value they get back from the machine (current)

Then they look that up in a table that is comprised of people that have been subjected to this machine and hydrostatic weighing. So its more like hey this guy had the same reading as you so you must have this score (and they checked the other with hydrostatic weighing).

This is all nice for people who fall in the normal range but for athletes its a different story.

This is how i understood it worked.. but if this has changed im interested in it. I just need a good test that i can do once in a while. Its good to measure progress as the scales are not good. I am still not good enough with the skin caliper. Ideally i would want a dexa scan but if other things fail then no problem.

Orac · October 20, 2012

Tolley, its just what i have read about these tests. Could be that i am wrong but as i understand it they look up the value they get back from the machine (current)

Then they look that up in a table that is comprised of people that have been subjected to this machine and hydrostatic weighing. So its more like hey this guy had the same reading as you so you must have this score (and they checked the other with hydrostatic weighing).

This is all nice for people who fall in the normal range but for athletes its a different story.

This is how i understood it worked.. but if this has changed im interested in it. I just need a good test that i can do once in a while. Its good to measure progress as the scales are not good. I am still not good enough with the skin caliper. Ideally i would want a dexa scan but if other things fail then no problem.

As a measure of progress would an impedence machine give consistant results even if not accurate ie. give a result you can calculate how much body fat as a percentage lost over a period of time rather than an empirical figure or do the results vary on the same machine over a period of time due to other factors?

Tolley · October 20, 2012

Tolley, its just what i have read about these tests. Could be that i am wrong but as i understand it they look up the value they get back from the machine (current)

Then they look that up in a table that is comprised of people that have been subjected to this machine and hydrostatic weighing. So its more like hey this guy had the same reading as you so you must have this score (and they checked the other with hydrostatic weighing).

This is all nice for people who fall in the normal range but for athletes its a different story.

This is how i understood it worked.. but if this has changed im interested in it. I just need a good test that i can do once in a while. Its good to measure progress as the scales are not good. I am still not good enough with the skin caliper. Ideally i would want a dexa scan but if other things fail then no problem.

As a measure of progress would an impedence machine give consistant results even if not accurate ie. give a result you can calculate how much body fat as a percentage lost over a period of time rather than an empirical figure or do the results vary on the same machine over a period of time due to other factors?

As long as you are properly hydrated when you do the tests you would think it should.

Edited October 20, 2012 by Tolley

Tolley · October 20, 2012

This might add some insight into how valid the equations are for BMI.

It seems to indicate that if you have a different body type or shape from the norm whatever the norm is then it is not going to be that accurate.

Predictive equations

Many empirical equations have been developed for estimation of TBW, FFM and body cell mass (BCM), by using sex, age, weight, height and race as explanatory variables. However, predictive equations are generally population-specific and can be useful only for those populations with characteristics similar to those of the reference populations [18,19]. When these equations have been used to predict body composition in different populations, the results have been inconsistent. The developed predictive equations cannot be generalized to diverse populations. Heyward and Wagner reviewed the reliability and validity of different equations for African Americans, Asians and Indian Americans. They found that the majority of studies indicated that the BIA method is not accurate when a generalized equation is applied for different ethnic groups [20].

Edited October 20, 2012 by Tolley

robblok · October 20, 2012

Tolly, like you show there the machine is not good.. and this is for the general population. Athletes are not general population. That is the reason why i want a dexa scan.

I got one of those hand held omron things and it says im obese. I will agree that what you have done probably gives better readings.

Anyway this is the reason why i want a dexa scan, then i can be sure. I just don't trust it because of the reasons i mentioned.

Tolley · October 20, 2012

Tolly, like you show there the machine is not good.. and this is for the general population. Athletes are not general population. That is the reason why i want a dexa scan.

I got one of those hand held omron things and it says im obese. I will agree that what you have done probably gives better readings.

Anyway this is the reason why i want a dexa scan, then i can be sure. I just don't trust it because of the reasons i mentioned.

Yeah they do seem a bit dodgy when you start looking at how they do the equations. I know the scales are useless but the ones as shown in the picture which is how i did it are probably not too bad. If you do that in conjunction with waist measurement and hip to waist ratio etc you will still get pretty close i reckon.

robblok · October 20, 2012

Tolly, like you show there the machine is not good.. and this is for the general population. Athletes are not general population. That is the reason why i want a dexa scan.

I got one of those hand held omron things and it says im obese. I will agree that what you have done probably gives better readings.

Anyway this is the reason why i want a dexa scan, then i can be sure. I just don't trust it because of the reasons i mentioned.

Yeah they do seem a bit dodgy when you start looking at how they do the equations. I know the scales are useless but the ones as shown in the picture which is how i did it are probably not too bad. If you do that in conjunction with waist measurement and hip to waist ratio etc you will still get pretty close i reckon.

I know and i might go for it if i can't find a dexa scan. Just trying to keep track a bit. Its a bit hard at times as you can gain muscle and loose fat ect.

CrazyKid · October 20, 2012

This is about Assessment of Body Composition and is kidney disease but it may be helpful. I did Dexa scanning as a Technologist and I am sure you know the scanners change over time due to use. Also many scanners are older models or Heel only scanners. A good rule of thumb; Look for a new machine and a old technolgist

http://ndt.oxfordjou.../19/9/2289.full

EDIt; I worked on the early research for gathering data for reference tables used in Dexa scanning. They are age and race specific. My suggestion is use any test you can, get a baseline reading and do it on a regular basis. You should be able to see a trend, better or worse.

Edited October 20, 2012 by CrazyKid

tropo · October 22, 2012

I did the bio impedience test a few years back maybe that is an option if you can't get the dexa here. I just copied this info from this website http://www.dh.org/body.cfm?id=1023

How Does BIA Work?

This non-invasive test simply involves the placement of two electrodes on the person's right hand and right foot. A low level, imperceptible electrical current is sent through the body. The flow of the current is affected by the amount of water in the body. The device measures how this signal is impeded through different types of tissue. Tissues that contain large amounts of fluid and electrolytes, such as blood, have high conductivity, but fat and bone slow the signal down. As BIA determines the resistance to flow of the current as it passes through the body, it provides estimates of body water from which body fat is calculated using selected equations.

For nutritionists providing dietary supplementation and individualized nutritional guidance, BIA helps to measure progress. For individuals using BIA, an improving or healthy BIA measurement can increase the likelihood that your body is functioning properly, aging well with a reduced risk of illness.

How accurate is it?

While no methods of body composition measurement are 100% accurate, the margin of error derived from BIA is 3-4%, comparable to the skinfold caliper method. The error margin for hydrostatic weighing and the "bod pod" is 2-2.5%. Near infrared method of body composition measurement has a 4-5% margin of error. The nutritionists of Healthy Directions choose BIA over other body fat methods due to the health information provided by BIA in addition to body composition. Participants of any of the programs offered by Healthy Directions are advised to continue with one method of body composition measurement, since the progress seen from each measurement is accurate.

Very important that you are probably hydrated for this test.

This must be an out-dated website because DEXA is not even mentioned. I've done bio-impedance (expensive machine at a university), hydrostatic and DEXA. DEXA is the gold standard of measurements only surpassed by a CAT scan. What makes it so useful is how it shows where all the bodyfat is hiding. I shall scan my latest results later to demonstrate this. I know you're going to be impressed.

Edited October 22, 2012 by tropo

tropo · October 22, 2012

Tolly, like you show there the machine is not good.. and this is for the general population. Athletes are not general population. That is the reason why i want a dexa scan.

I got one of those hand held omron things and it says im obese. I will agree that what you have done probably gives better readings.

Anyway this is the reason why i want a dexa scan, then i can be sure. I just don't trust it because of the reasons i mentioned.

I have a handheld Omron bodyfat monitor - HBF - 306. Right now it's showing 7.0% body fat, which isn't too far off my true measurement... but when I was fatter it was still giving super low measurements, so it really is useless.

tropo · October 22, 2012

Tolly, like you show there the machine is not good.. and this is for the general population. Athletes are not general population. That is the reason why i want a dexa scan.

I got one of those hand held omron things and it says im obese. I will agree that what you have done probably gives better readings.

Anyway this is the reason why i want a dexa scan, then i can be sure. I just don't trust it because of the reasons i mentioned.

Yeah they do seem a bit dodgy when you start looking at how they do the equations. I know the scales are useless but the ones as shown in the picture which is how i did it are probably not too bad. If you do that in conjunction with waist measurement and hip to waist ratio etc you will still get pretty close i reckon.

I know and i might go for it if i can't find a dexa scan. Just trying to keep track a bit. Its a bit hard at times as you can gain muscle and loose fat ect.

You hit the nail on the head. If you're trying to lose fat and gain muscle at the same time a DEXA measurement is perfect way to determine progress.

hhgz · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calculator.net/body-fat-calculator/

http://www.linear-software.com/online.html

http://www.scientificpsychic.com/fitness/diet.html

http://www.calculator.net/body-fat-calculator.html

http://www.livestrong.com/tools/body-fat-calculator/

Tolley · October 22, 2012

Tolly, like you show there the machine is not good.. and this is for the general population. Athletes are not general population. That is the reason why i want a dexa scan.

I got one of those hand held omron things and it says im obese. I will agree that what you have done probably gives better readings.

Anyway this is the reason why i want a dexa scan, then i can be sure. I just don't trust it because of the reasons i mentioned.

I have a handheld Omron bodyfat monitor - HBF - 306. Right now it's showing 7.0% body fat, which isn't too far off my true measurement... but when I was fatter it was still giving super low measurements, so it really is useless.

7 percent that is pretty low.

My lowest ever was 11 percent and that was done at UNSW when I was playing state grade squash and twenty years yoounger. I was generally around 14 percent when I was really fit.

Now I am closer to twenty.

Since we are talking about fat here one of the biggest factors for me putting on weight was getting older of course and I am sure due to falling testosterone.

robblok · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

Thanks for the effort, but im not interested in that. I got a skin caliper here and an omron device. Both are not as accurate as a dexa scan. Im now serious with my training and am willing to spend some money on checking the fat percentage.

Tolley · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

Thanks for the effort, but im not interested in that. I got a skin caliper here and an omron device. Both are not as accurate as a dexa scan. Im now serious with my training and am willing to spend some money on checking the fat percentage.

It is still probably worthwhile doing and then comparing it to what you get with the DEXA scan.

robblok · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

Thanks for the effort, but im not interested in that. I got a skin caliper here and an omron device. Both are not as accurate as a dexa scan. Im now serious with my training and am willing to spend some money on checking the fat percentage.

It is still probably worthwhile doing and then comparing it to what you get with the DEXA scan.

If i can locate one that is. Anyway we will see, i know im making progress at the moment. Its more that i could do like a half year or quarterly test (depending on where and the price). Next year will be the year i reach my goal. I should be able to get there in a year. Especially because i'm not that far of anymore.

As long as i don't put on too much weight on my holiday with my parents. But i will try to keep that at a minimum.

Tolley · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

Checked mine and it comes it at 19 percent on a couple of these tests and I reckon that would be just about right based on what I have tested before and my weight now.

It would now be interesting to see the DEXA results to see how closely they align.

robblok · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

Checked mine and it comes it at 19 percent on a couple of these tests and I reckon that would be just about right based on what I have tested before and my weight now.

It would now be interesting to see the DEXA results to see how closely they align.

I would rather use my skin caliper to take these tests. I might ask the gf to do them later. I got a digital skin caliper from the phuket health shop.But it takes a bit of skill to take the right skinfolds.

I am actually not that interested at the percentage, but more at progress. Just a wraist measurement does not help me much as my abs are slowly starting to stick out now the fat around it is going away. I am also doing more ab exercises to get them a bit bigger now the fat is slowly going away.

tropo · October 22, 2012

7 percent that is pretty low.

My lowest ever was 11 percent and that was done at UNSW when I was playing state grade squash and twenty years yoounger. I was generally around 14 percent when I was really fit.

Now I am closer to twenty.

Since we are talking about fat here one of the biggest factors for me putting on weight was getting older of course and I am sure due to falling testosterone.

You misunderstood the nature of my comment about the hand held Omron meter. I am not 7% body fat - that's what the meter consistently shows or lower, even when I'm over 15%. The point is that this device is BS and a waste of money.

It's the increasing estrogen which is most responsible for fat gain as you age. Another likely reason is insulin resistance coupled with too many carbs in your diet.

Edited October 22, 2012 by tropo

tropo · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

The 2nd link you provide is very useful, thanks!

.... it requires a pinch calliper.

Edited October 22, 2012 by tropo

tropo · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

Thanks for the effort, but im not interested in that. I got a skin caliper here and an omron device. Both are not as accurate as a dexa scan. Im now serious with my training and am willing to spend some money on checking the fat percentage.

I know I've mentioned this before, but just to recap....

Back in 2010 I had a DEXA scan which came out at about 17% body fat. My pinch calliper result was about 11% (9 positions) at that time. The 6% difference was visceral fat. Most pinch calliper calculations don't factor in age. Now, after some hard effort my pinch calliper result is the same as my DEXA result because I've eliminated my excess visceral fat. Interestingly, at 17% I had ab definition with a 40 inch waist. Not razor sharp, but they were visible. I was pinching about 10mm thickness over the abs.

tropo · October 22, 2012

. I am also doing more ab exercises to get them a bit bigger now the fat is slowly going away.

This is a good point. When there's a fat covering over the abs, making the ab muscles larger makes the region look bigger and fatter. I'm always amazed at how many people at the gym slave away at ab work when they're carrying a lot of bodyfat. A limited amount of weighted ab work to keep the area strong should be enough for people who's abs are not visible. Doing hundreds of ab crunches is big waste to time and effort which could be spent either on cardio or preparing a wholesome low carb meal.

Edited October 22, 2012 by tropo

robblok · October 22, 2012

Here are a few, and they only require a cloth tape measure:

http://www.bmi-calcu...fat-calculator/

http://www.linear-so...com/online.html

http://www.scientifi...tness/diet.html

http://www.calculato...calculator.html

http://www.livestron...fat-calculator/

The 2nd link you provide is very useful, thanks!

.... it requires a pinch calliper.

Using my caliper i get some reading that id love to believe but am sure are wrong. I am using the 3 point one and get around 10% from my readings. I don't believe it i must be around 14% i guess.

Have tried the 3 point a few times.. problem was chest measurement as its hard to grab fat there without muscle.

tropo · October 22, 2012

Here's the trick. Flex the chest muscle as you're grabbing the skin... then it's impossible to grab muscle.

Try that online 7 point method. It correlates perfectly to the DEXA scan results for me.

Here it is:

http://www.free-online-calculator-use.com/skin-fold-test.html

tropo · October 22, 2012

OK, as promised, DEXA results. I'm also going to include some info pages.

If you're looking at the results closely you may notice a K-nail in the left femur. This weighs about 400 grams and scews the BMC and BMD slightly.

There is also 2 results given for total body fat percentage, 8.9 and 9.5%. The 9.5% is a scewed result because the head is always around 20% fat. Not taking the head into consideration gives 8.9%. You cannot reduce the head below about 20%. It's essential fat in the brain.

Edited October 22, 2012 by tropo

Tolley · October 22, 2012

7 percent that is pretty low.

My lowest ever was 11 percent and that was done at UNSW when I was playing state grade squash and twenty years yoounger. I was generally around 14 percent when I was really fit.

Now I am closer to twenty.

Since we are talking about fat here one of the biggest factors for me putting on weight was getting older of course and I am sure due to falling testosterone.

You misunderstood the nature of my comment about the hand held Omron meter. I am not 7% body fat - that's what the meter consistently shows or lower, even when I'm over 15%. The point is that this device is BS and a waste of money.

It's the increasing estrogen which is most responsible for fat gain as you age. Another likely reason is insulin resistance coupled with too many carbs in your diet.

Okay but I read in another post that you are around 9 percent for which for your age is pretty impressive.

You are right about the estrogen I reckon. I am not sure about the carbs because I have very low blood sugar readings. Having said that I am sure I could reduce my carbs and lose fat but I need to enjoy my food and life too so while I should be a little lower in body fat I am not suffering any adverse conditons from it.

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