Calculate your % Body Fat

[campagman]

I thought that this wasn't going to be very accurate but the figure I got was very close to the last time I had my %BF measured (bioimpedance).

[Ewan Houzami]

Mine is 75%

[phantasmagoriana]

Just don't try it with metric measurements (no, I didn't read the instructions properly first ). The results may be a bit alarming...

[Ewan Houzami]

I used inches as instructed and so assumed the weight to be in pounds.

EDIT: Sorted now. I'm under ten stone but I still come in the 'Step away from the chips, please sir' bracket.

[mrcharly-YHT]

18.28%
For my age, it is allegedly 21-24

Seems ok.

[hellymedic]

I've guessed some measurements or rounded figures. My 19.3% is not believable (I reckon I'm nearer 25%) but David's 11% is, though I'd guess he's a little thinner. The formula seems much more complex for women so might be less reliable.

[Nelson Longflap]

I've guessed some measurements or rounded figures. My 19.3% is not believable (I reckon I'm nearer 25%) but David's 11% is, though I'd guess he's a little thinner. The formula seems much more complex for women so might be less reliable.

Otoh I was surprised by the simplicity of the calculation. For men %bf is a function of weight and waist size only, and for women weight, waist size and circumferences of wrist, forearm and hips. The formula for women looks like something that might have been generated by expert system software ... ?

We might suppose the numbers that transform the measured data into %bf derive from studying a large number of individuals.  Does anybody know? 

My %bf turned out to be 10.6%. My waist height ratio is 0.42 which I guess must correlate with %bf (but IANAD).  However I don't know enough about the domain to know whether my %bf result is credible or not, so remain doubtful rather than sceptical. 

[hellymedic]

David's waist:height is also 0.42 so around 10% fat seems 'about right'. His BMI is 19.3.

[Nelson Longflap]

David's waist:height is also 0.42 so around 10% fat seems 'about right'. His BMI is 19.3.

As we are trading vital statistics, my BMI is 20.9 so as you say, a good correlation with David's stats. However similar numbers in will yield similar answers out. I still don't really know if our %bf numbers are even ballpark correct

BMI and waist/height ratio are commonly used as some sort of proxy for f@. If the formulae here are correct we have the beginnings of a Grand Unified Theory directly linking easily measured data with %bf.  I assume that the underlying theory has a statistical source, so (next question) presumably comes with some error bounds.

I'm intrigued enough to look into it a bit further.  Will post here if I turn up anything useful.

[hellymedic]

ISTR my body fat was estimated at 24% at some 'health promotion' stall 20 odd years ago. I weighed about 3kg more than I do now. I think they used an ultrasound gadget to gauge fat over the biceps.

My waist measurement was almost definitely less then and I was more muscular.

We did more formal measurements at university, where we did skinfold thickness measurements at 4 sites: biceps, triceps, subscapular and suprailiac. I was around 71kg then and was 33% fat by that calculation.

[DrMekon]

I'd someone wants to do the numbers, I know I'm 7.3% body fat at 71.5kg and 30.0" waist. Fat was by DEXA. IIRC, I'm 5% on top, 12% below, which should mean I could twerk effectively. Really, it means I have love handles even when I look a bit like skeletor and my arms look like a junkies dream.

[Nelson Longflap]

I'd someone wants to do the numbers, I know I'm 7.3% body fat at 71.5kg and 30.0" waist. Fat was by DEXA. IIRC, I'm 5% on top, 12% below, which should mean I could twerk effectively. Really, it means I have love handles even when I look a bit like skeletor and my arms look like a junkies dream.

Subject to my arithmetic being correct and you being a male of the human species, the formula says you are 10.9%bf. So which do you believe? 

Never go to sea with two clocks.  (Take one or three.)

[Clare]

I've never had my body fat measured but according to that calculation I am 22.25% BF which, I think, is complete toot. I think I'd be around 30% and, quite probably, the wrong side of 30% at that. I do have skeletal wrists and forearms though and a small waist compared to the rest of me. This has probably skewed the result.

[Nelson Longflap]

I think I'd be around 30%

How do you get that preconception?  Gut feeling? 

[Clare]

Well, given that my breasts are about 3.5% of my body weight...


but, yeah, gut feeling or to be more precise gut looking.

 

[Nelson Longflap]

Well the tape measure method at
http://www.linear-software.com/online.html
says my %bf is 24.21% (I especially like the precision of this answer nailing me down to one ten thousand part of my weight.) I'm very sceptical about this as it's such an outlier value, I'm wondering if they or I have made a mistake over units, like when NASA muddled inches and mm.

In contrast the tape measure method at
http://fitness.bizcalcs.com/Calculator.asp?Calc=Body-Fat-YMCA
says my %bf is 7%

Using the pictures at
http://www.nerdfitness.com/blog/2012/07/02/body-fat-percentage/
to compare whose body is most like mine I'm closer to the 9-10% body than the 14-15% body (NBB: HUGE scope for wishful thinking using this method; take reality check pills before and after)

http://www.scientificpsychic.com/fitness/diet.html
says my %bf is 9.3% While I remain doubtful about this answer this page does include some reputable references and the method appears to be the one developed by Hodgdon and Beckett at the US Naval Health Research Center in 1984. I think the measurements are in cm (haven't checked as I just used their online calculator); the formula for men is:
%Fat=495/(1.0324-0.19077(log(waist-neck))+0.15456(log(height)))-450
The formula for women is:
%Fat=495/(1.29579-0.35004(log(waist+hip-neck))+0.22100(log(height)))-450

The original paper can be found at
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA143890
Their results are based on measuring 602 male navy personnel who were subjected to various skinfold and underwater measurements. Results were analysed using SPSS (a standard statistical analysis package - hence the wacky coefficients appearing in the formulae). The paper appears rigorous and so we might have some confidence in the results.

My conclusion is that the method pointed to in the OP is (probably) acceptably useful, and the dtic method offers a useful comparison.

Thanks campagman 

[Cudzoziemiec]

I don't follow the logic of this at all. You use a formula to calculate your lean muscle mass. Ok so far. Then you subtract this from your body weight to find the fat. That seems to assume everything which is not muscle must be fat. What about bones and organs?

[hellymedic]

I think they mistook 'lean body mass', which includes bones and organs, for lean muscle mass.

I'd assumed they meant lean body mass anyway.

I don't think the whole thing is as accurate as the numbers might suggest.
My wrists (and David's) have shrunk as we have lost weight. There's a fair amount of fat round the wrists of most people.

[DrMekon]

I'd someone wants to do the numbers, I know I'm 7.3% body fat at 71.5kg and 30.0" waist. Fat was by DEXA. IIRC, I'm 5% on top, 12% below, which should mean I could twerk effectively. Really, it means I have love handles even when I look a bit like skeletor and my arms look like a junkies dream.

Subject to my arithmetic being correct and you being a male of the human species, the formula says you are 10.9%bf. So which do you believe? 

Never go to sea with two clocks.  (Take one or three.)

DEXA - it's the gold standard for BF measurement, although our sports physiologist reckons her BodPod is better. I'm waiting until just before I hit peak fitness before I submit myself to her examination, as it'll inevitably get shown around colleagues.

Re. the pictures, I think they are a poor guide. I do some core work (several 2min planks a day, press ups, shoulder taps, etc). This is me at 68.1kg - BMI 19.1 (so BF likely to be sub 7%) - excuse the blood, I'd just been knocked off. I reckon I look somewhere between the 9-10% and 10-14%. I have veins showing on my abdomen and still no 6 pack.

(click to show/hide)

FWIW, I reckon cyclists won't fit that self-measurement model well. Compared to navy personnel, our legs will weigh more than average, and our waists will be smaller - it'll give too high a BF%. Note that they only validated the model against more navy personnel.

[Cudzoziemiec]

I think they mistook 'lean body mass', which includes bones and organs, for lean muscle mass.

I'd assumed they meant lean body mass anyway.

I don't think the whole thing is as accurate as the numbers might suggest.
My wrists (and David's) have shrunk as we have lost weight. There's a fair amount of fat round the wrists of most people.

Lean body mass - thanks!

[L CC]

FWIW, I reckon cyclists won't fit that self-measurement model well. Compared to navy personnel, our legs will weigh more than average, and our waists will be smaller - it'll give too high a BF%. Note that they only validated the model against more navy personnel.

hahahahahha.
It gave me less than 15%.
I carry so much lard I float.

The pictures are probably a better guide for wimmin. I'm certainly around 30%, and like Clare, reckon the wrong side of that, but I'd love a pod/DEXA scan, just to prove that under the normal-sized woman's lard there's a hulk of muscle longing to be revealed, which is why I'm so wide.

Of course, it's probably just more lard.

[Bledlow]

That formula gives me 18% fat. The US navy one works out at 14%. BMI 21.6.

[DrMekon]

FWIW, I reckon cyclists won't fit that self-measurement model well. Compared to navy personnel, our legs will weigh more than average, and our waists will be smaller - it'll give too high a BF%. Note that they only validated the model against more navy personnel.

hahahahahha.
It gave me less than 15%.
I carry so much lard I float.

The pictures are probably a better guide for wimmin. I'm certainly around 30%, and like Clare, reckon the wrong side of that, but I'd love a pod/DEXA scan, just to prove that under the normal-sized woman's lard there's a hulk of muscle longing to be revealed, which is why I'm so wide.

Of course, it's probably just more lard.

If you come up, I'll see what I can do. Leeds are way more accommodating than Cambridge where when it comes to playing with toys. A VO2 max session on exercise bikes might also be on - you versus Chris?

[L CC]

If you come up, I'll see what I can do. Leeds are way more accommodating than Cambridge where when it comes to playing with toys. A VO2 max session on exercise bikes might also be on - you versus Chris?

That would be grand. We certainly hope to come up before too much time passes.
I hesitate to speak for Chris, him being a grown up and more than capable of his own typing and whatever, but I'd guess he'd be less keen on a VO2 max session than me- far too much risk of parking your lunch.

[simonp]

VO2max test = hell.

The main thing I learned from the testing was that I needed to lose weight. I’m now heavier than I was back then.