Body composition monitor...

[andyoxon]

Anyone use one..?  I bought one for us from Loyd's phramacy for £4.99  - says I'm:
19.8% Fat, 59%water, 76% muscle, 20.5BMI (non athlete mode).  Book says healthy range is Male age 40-59 = 13-25% ( age 20-39 = 11-22%) I was surprised I wasn't lower, fat wise, given I'm 6'2" (188) and 73kg... 

[Maladict]

Well, there are various reasons why it could be off.

One of those is dehydration, which would tend to increase the % fat.

If it's any comfort, I am only a couple of inches shorter, about the same weight, and when I started I was also getting about 19%.

I'm now getting about 15-16% typically, after having spent the last 3 years going audax mad.

Also it tells me my "metabolic age".  I've had that as low as 23, and typically it says I about 25-27, i.e. 10 years younger than I am.  When I started out it said I was about 30.    A load of nonsense if you ask me, but quite nice of it to be so complimentary. 

[Chris S]

Mal Volio is the local authority on BCMs.

Clearly, at 1.9m and 73Kg, you're not fat. I'd be astonished if you were 20% fat. Monitors costing £4.99 probably get you the result you paid for, but in any case, electrical impedance is not a great way to measure an absolute fat level.

FWIW, I'm 1.85m and 91Kg (much wobblier than you). My BCM says my BF is 21%.

As has been said before on this forum (and its predecessor) the mirror test offers a much better cost/accuracy ratio; ie: strip off, stand in front of a mirror and jump up and down. If it wobbles and shouldn't, it's probably excess.

[hellymedic]

+1 to Chris S.

At 6'2" and 11½ stone, you are somewhere between 'slim' and 'beanpole'. Unless you have tiny bones and little muscle, 20% fat is not likely to be a true figure.

'Pinch an inch' and the wobble test sound more helpful as global fat measures.

[andygates]

Those gidgets are only reliable as trend indicators.  Use them under the same conditions (say, first thing in the morning after your ablutions) and they will give consistent results; not necessarily accurate, but at least consistent.  For any real use to be got out of 'em you need a graph and error bars and trend lines.

FWIW, I reckon (by comparing variability) that my BCM scale gives a %bodyfat error range of +/- 2.5%, where calipers give +/- 1%.  That's before you come to any offset for being a cyclist (scales seem to go daft with disproportionately muscular legs). 

[border-rider]

Those gidgets are only reliable as trend indicators.  Use them under the same conditions (say, first thing in the morning after your ablutions) and they will give consistent results; not necessarily accurate, but at least consistent.

Possibly, but - consistent or not - that result won't be an indicator of body fat.

The clinical-grade, 4-ECG electrode wrist/ankle ones are usable with a lot of provisos and a great deal of care to normalise hydration.  The stand-on/grab ones are just junk.

scales seem to go daft with disproportionately muscular legs

Yes - and if you look at the physics of what is going on it tells you that the data you get are only related to how much water is in your ankles

Mal Volio is the local authority on BCMs.

My PhD was in body composition analysis using RF - and I did a clinical trial comparing RF/K40/tritium dilution/skinfold/impedance analysis as part of it.  My working life since has involved a lot of calculation/measurement of current flow through the human body.

[Fixedwheelnut]

 You have to stand on it with one leg and touch the other plate with your opposite hand 

[andygates]

So, Mal, do you consider a 4-site skinfold to be a decent test?

[Otto]

Apparently the only acurate way to measure body fat is a displacement tank type thing filled with water not sure how it works but its something to do with muscle being denser than fat !!

PS I'm 6'1" 78.8 kilos and 18.3% blubber as measure by an electronic stand on thingy

[nuttycyclist]

So, Mal, do you consider a 4-site skinfold to be a decent test?

I've been in here too long.   I read that as a 4-skin sitefold and wondered wtf was required

[border-rider]

So, Mal, do you consider a 4-site skinfold to be a decent test?

Sorry, only just seen this (thanks to Nutty )

Yes, not bad - if done by either the same person or someone who does it a lot.  Obviously it's only telling you about subcutaneous fat and not the stuff that's mixed up with the rest of you, but there's a reasonable correlation there.  It is at least measuring fat and it should be OK for tracking changes, even if the absolute value may be a bit suspect (relies on statistical correlation relationships - caveat, caveat, caveat)

[border-rider]

Apparently the only acurate way to measure body fat is a displacement tank type thing filled with water not sure how it works but its something to do with muscle being denser than fat !!

That's one way...works quite well but it's not too suitable for the ill, elderly or infirm.  It's just measuring density.  Fat is less dense, muscle more so so the density is a pretty-good correlate for body composition.

I posted on a different thread my idea for using non-Newtonian liquids for this: get the patient to stand in a  bowl of custard, hit it (the bowl) with a piece of wood (other substances may be available) and measure the ringing frequency of the system and its harmonics.  Hey presto - volume.  Then weigh 'em and you have density.  They wouldn't let me, though

K40 counting is another, as is tritium dilution - but that's a clinical technique cos it requires ingesting radiowotsits.    K40 just needs a whole-body scintillation detector.  Every shed should have one.

[mattc]

My working life since has involved a lot of calculation/measurement of current flow through the human body.

You're an executioner? I knew justice was harsh in Wales ...

[border-rider]

You're an executioner?

Never intentionally.