So I’ve started reading “Race Weight”, popped out to get some scales that measure Body fat and, 23.3% or “Average”. 🙁

I thought I was fit. Still, the good news is that I have a good chance of being fitter and faster by getting to my first goal (19.6%) in May) 🙂

Whats yours?

P.S. 1 chapter in and I’ve already found this book excellent.

queue bickering about body fat measurement methods

I’ve just eaten an apple rather than a Jaffa cake, I can feel the improvement already.

mine’s about 89%

Doesn’t really matter re accuracy as long as it’s consistent and you can see a trend.
I got some withings scales, web/wifi enabled, they’re great!
(14% btw)

18% or so measured with DXA X ray thingy.

How is body fat related to fitness?

It’s not directly linked to fitness but it’s a good indicator.

My waist to Hip ratio is 1:1 which makes me extremely obese. BMI puts me close to the bottom of normal range. Body fat monitor based on electric signals that has sensors at both feet and hands gave me 15% IIRC.

These are all indicators which on their own are pretty much unreliable.

FWIW the typical bathroom fat monitors only have sensors in the feet and so only get a picture of whats going on in your legs. If you have the hand sensors as well they can send different signals round to get a more complete view.

How is body fat related to fitness?

The thinner you are, the less wind resistance you create.

So you go quicker.

IANAD.

The reason why they recommend losing the fat is because its pointless weight that you’re carrying around, you’ll make more use of your energy as it will be expended in forward (or upward) momentum.

Ergo your fitness remains the same but you can do more with it.

ok, bear with stupid here, but how do scales measure fat content? you have to also do an archimedies style “bath experiment” to work the volume you displace too???

From Wikipedia:
The bioelectrical impedance analysis (BIA) method is a lower-cost (from less than one to several hundred US dollars in 2006[11]) but less accurate way to estimate body fat percentage. The general principle behind BIA: two or more conductors are attached to a person’s body and a small electric current is sent through the body. The resistance between the conductors will provide a measure of body fat between a pair of electrodes, since the resistance to electricity varies between adipose, muscular and skeletal tissue. Fat-free mass (muscle) is a good conductor as it contains a large amount of water (approximately 73%) and electrolytes, while fat is anhydrous and a poor conductor of electric current. Factors that affect the accuracy and precision of this method include instrumentation, subject factors, technician skill, and the prediction equation formulated to estimate the fat-free mass.

as per damo2576 there’s no point arguaing about accuracy but obvioulsy if you are currently 23% on a set of scales and get down to 15% on the same set of scales then you’re losing fat. And if as said above the scales can only measure fat content of your legs then its likely if you’ve lost fat there then you’ve lost it in other places too.

19.1% here and on a downward ternd. Using withings scales btw.

Presumably fat conducts electricity in a different way from muscle/blood/bone so scales with sensors can measure the body fat in your feet and extrapolate that to the rest of the body based on average figures.

looks to be inaccurate but comparing like for like with the same person on the same scales should show the trends.

Well i just measured 1.8Mohms across my feet with dry feet, and 0.2Mohms with wet feet. So, i’m either all muscle or all fat, one of the two.
Tell you what, i’ll just kick myself and see how long i wobble for………. 😉

They measure the electrical resistance through your body (scales do it through tour feet/legs), water conduicts better than fat, so based on that they can figure out how much fat there is.

Some others work on the same principal but you hold onto a device so it uses hands/arms. Others use all 4, (some of) those can even tell you the imbalance of muscle between left and right*!

There are others like DEXA scanners which x-ray your body and estimate based on that. Others measure your volume by sitting in a pod and altering the air pressure slightly, then compare that to your weight. Or callipers to ‘pinch’ the fat at various points on the body. The dunking in a pool method’s gone out of fassion for being uncomfortable 9you need to competely empty your lungs for an accurate reading), and being time/space consuming.

*I broke my left arm last year, that’s my excuse and I’m sticking with it!

Well i just measured 1.8Mohms across my feet with dry feet, and 0.2Mohms with wet feet. So, i’m either all muscle or all fat, one of the two.

all wet feet does is improve the contact between the pin on the multimeter and your body, the bigger pads on scales do a better job. Do you think a fraction of a mm of water on the sole of your feet makes more or less difference than about 2m of feet/legs/hips (which are also mostly water) that it also has to measure?

Out of curiosity.. do/should you get a different figure if you stand on one leg with one hand on the scales?

Should be easy enough to measure body fat when rendering, convenient at that stage to scoop off whatever amount you want to have the desired percentage.

I have had mine done using 3 methods on several occasions(scales, electric nodes on various point of the body & calipers). Was surprised that they were pretty consistent on all occasions across all 3 methods

I am now registering around 12 – 13 % on my scales steadily down from 25% around 5 years ago.

Not directly related to fitness. But carrying less ‘dead’ weight has many benefits for cycling effiency and speed, especially accelerating & climbing. You also tend to drop fat as you get fitter assuming the diet is reasonable

Tell you what, i’ll just kick myself and see how long i wobble for………

The Simpson Test.

[video]http://www.youtube.com/watch?v=3jGk7sy0X34[/video]

thisisnotaspoon

Do you think a fraction of a mm of water on the sole of your feet makes more or less difference than about 2m of feet/legs/hips (which are also mostly water) that it also has to measure?

well my quick measurements suggest that it does (I was 200Kohm with wet probes, so that must be getting close to the resistance of my actual body, but 9x as much with dry probes, suggesting the probe/body interface can be as small as a few 10x of Kohm, and as big as 1.MOhm depending on the contact surface condition!)

Not that i’m arguing that those scales don’t work or aren’t accurate, just interested to know the science (and compromises) behind the measurement technique.

For example, does having big feet, and a large contact area make you look less fat to the scales? (does my bum look fat in these feet………;-)

This isn’t about weight – thats important understand – this is about “body composition” – being lean not thin; carry the optimum amount of fat/muscle mass for your given sport, not too little, yet not too much.

Loving this book btw, can you tell?

Aye, tis a good book I seem to remember.

The one with ‘targeted snacking’?

What about those strange creatures – the fit fat.

Mr 8% body fat TSY would love this thread. 😈

I’m still reading racing weight. Its good but I got a bit of a shock when it suggested 5kg weight loss based on where i wanted to get to in that chart! I’ve given up anything bad for me, so I’d better smash this years ramp test and race PBs!

I have know idea and frankly don’t care what my BMI is. However, if I look in the mirror and see bits that ‘quiver’, then I reduce food intake and up fitness efforts!

Tends to work…..

Rockape63 – Member
I have know idea and frankly don’t care what my BMI is. However, if I look in the mirror and see bits that ‘quiver’, then I reduce food intake and up fitness efforts!

Tends to work…..

Thats what you think – you may be comnprimising your body’s ability to maximise its performance.

piemonster – Member
Aye, tis a good book I seem to remember.

The one with ‘targeted snacking’?

If it has, I haven’t got there yet.

Argh thanks Kryton, I was trying to avoid buying this book as it’s another thing to obsess about. I may now have to get it. Currently 8% on a pair of fancy scales (which is surprising as I’ve just eaten a box of tunnocks tea cakes!) which sounds ok but really I’ve no idea.

Thats what you think – you may be comnprimising your body’s ability to maximise its performance

I did that many years ago…..when I got old! 🙁

Thats what you think – you may be comnprimising your body’s ability to maximise its performance.

Besides….I burnt 735 Kcal on the cross trainer in the 36mins the other evening…..takes a bit of doing!

mrblobby, 8% is elite cyclist territory. Although if you are a rower your are not at your optimum body composition.

TBH, for me this is about food discipline as well. I’ve put on 1/2 stone in 4 months eating crap. I want to be able to make educated choices and discplined refusals rather than reaching for the nearest bacon roll and slamming a Gel down on a club ride.

A lot of the book is as much about what you eat and when, as well as how much – this to me is the intriguing bit

Before xmas I went on one of the scales in Boots and was, from memory, about 14%, which was in the excellent bracket. I wouldn’t however call myself really fit.

The thinner you are, the less wind resistance you create.

So you go quicker.

IANAD.

So Usain Bolt would be even quicker if he had the figure of a marathon runner!

Rockape63 – Member
Thats what you think – you may be comnprimising your body’s ability to maximise its performance.

Besides….I burnt 735 Kcal on the cross trainer in the 36mins the other evening…..takes a bit of doing!

Good work, but how many calories did you take in and where they organic meat and vegetables or processed hamburgers and pies – which pretty much sums up the education bit I’m requiring?

fathomer – Member
Before xmas I went on one of the scales in Boots and was, from memory, about 14%, which was in the excellent bracket. I wouldn’t however call myself really fit.

You have to take into account muscle mass and aerobic capacity as well when you mention “fit”. Being skinny does not equal fit, else the geezer in Seven would have popped out of bed and scarpered down the street in 0.056 seconds.

Mmmm bacon roll *drool*

So Usain Bolt would be even quicker if he had the figure of a marathon runner!

If he could maintain the same power, cadence and stride length, then I guess he probably would!

Edit: … and book ordered. Thanks Kryton!

Not that i’m arguing that those scales don’t work or aren’t accurate, just interested to know the science (and compromises) behind the measurement technique.

For example, does having big feet, and a large contact area make you look less fat to the scales? (does my bum look fat in these feet………;-)

Mine have 50p sized pads to stand on, I’m assuming that the bigger pad means a better contact, minimising the effect of skin moisture. Whereas a small (pin on a multimeter) contact would give high resistance as the resistance accross the pin/skin interface would be huge. But the pad isn’t so big that small feet wouldnt cover it.

Like this:

http://www.argos.co.uk/static/Product/partNumber/8333951.htm

Good work, but how many calories did you take in and where they organic meat and vegetables or processed hamburgers and pies – which pretty much sums up the education bit I’m requiring?

The thing is you can obsess about these things, which tends to last for a period of time, be it a month or a year….or you can lead a life that allows you to eat bacon rolls, as well as more healthy options. In the same life, you can have periods of ultra fitness, periods of laziness and not worry too much about it.

As long as the overall balance is keeping you fit and healthy…..and you enjoy what you do and what you eat, then that will do for me!