BMI and alternatives for weight 'screening'

[SteveC]

From a thread in "Politics and Other Big Issues"...

As an aside, the BMI charts are to be reviewed as they have been show to be too low.  They were based on data that is very out of date and partial.  'Safe' weights will be estimated upwards, as happened with baby birth weights a few years ago.

BMI is a very crude measure in many ways, as it doesn't take account of factors such as build or body fat levels.

I've revived this on the grounds that New Year is a time a lot of us think about weight.
Has this review happened?  Are there any preliminary figures?  Anyone got an alternative 'screening' method for working out if you're overweight or not?  I'm thinking of doing some 'collective' slimming at work and with the morris team so some sort of 'scientific basis' would be useful.

Thanks

Steve

[Regulator]

Hi Steve

According to Mr R, the new BMI charts are still some way off and they are unlikely to be published much before 2011 or 2012.  There's a lot of work going on amongst the various National Institutes of Health (or their equivalents) worldwide to gather the data and agree the measures.  As with any such collaborative programme of this scale, things tend to progresss slowly.

From what I understand, it is suggested that the current best practice is to use BMI in conjunction with a Waist Circumference measure (this deals with some of the issues like high BMI athletes).  Some health professionals prefer now to use Rohrer's Index*, which takes into account body width and girth.










*I'd never heard of Rohrer's Index until I talked to Mr R's sister, who is an actuary.  Apparently it's used by a lot of medical insurers.

[border-rider]

I did a load of stuff on body composition when I was doing my PhD - it was more than twenty years ago so I'm not au fait with the latest on BMI but I agree with Reg that the crude number commonly used is a poor indicator of body fat.  

I spent some time delving into the origins of the statistical relationships behind the historical body composition indices, and they're not very well-established.  In particular if you are a cyclist they're going to be way out; if you're a female cyclist older than about 35 they'll be a long way out.

In the end, the best estimate of whether you're overweight is either something techie like K40, or standing in front of a mirror and seeing what wobbles

[SteveC]

In the end, the best estimate of whether you're overweight is either something techie like K40, or standing in front of a mirror and seeing what wobbles

The idea of doing that with the entire morris team   

The basic problem is that we have one or two people who are convinced that they are not overweight, that they are 'pretty fit' and that the BMI system is completely wrong.  As at least one of them is currently carrying an injury and we're pretty short of dancers as it is, I could do with something which is an 'update' to the BMI and is measurable so the individuals involved can work it out for themselves.

S

[oncemore]

Oh dear....I may fade away before the new decade!

Using          Body-Mass Index, Waist-to-Height Ratio and More...

my BMI is 18.6, WHtR 42%, body fat 9.2, Willoughby Athlete weight should be 172lbs (c.f. 130) and W A waist 31.6" (c.f. 29").

I must eat more, I must EAT....

Altho' fags usually linked with "obesity" I simply can't smoke MORE. I don't have time...

[Zoidburg]

"Waist is measured at one inch above the navel?"

Thats my over the bottom of my ribcage.

[andygates]

Waist? I've heard of this thing. 

Clearly the airport security guys should use their nekkid scanners to also give a completley accurate composition.   

[Cudzoziemiec]

I have several inches above my navel which are waste, and quite a few below!

[andygates]

'Travesty' would be closer to it...

[Dunedin]

What about saying a complete "heresy" and say forget scales / your weight and even measuring your weight just concentrate on losing fat from your waist by eating sensibly

Your trouser waist band will soon tell you whether you are losing body mass, it is also amazing the effect you will get if you use a few gentle "stretching" exercises will improve your posture and general well being

I found that taking a more relaxed / mature attitude to this that you will more likely succeed in the long term ..I did dropping 2 trousers sizes / a jacket size 

[SteveC]

What about saying a complete "heresy" and say forget scales / your weight and even measuring your weight just concentrate on losing fat from your waist by eating sensibly

Very sensible advice, once you've worked out that you have a problem.   
The people I'm dealing with need convincing that they are actually overweight to start with.
And me telling them so doesn't help.
So I was looking for a 'mechanistic' method other than BMI.

I'm not 'getting' at you, Dunedin.  It's just that I need something else for this particular group of people.

S

[hellymedic]

Dunedin's approach is fine for him and a tape measure is cheap and lightweight.
I think SteveC probably needs to use skinfold calipers on his associates, combined with various reference tables.
Another approach might be to use those posh 'body fat' scales that measure something electrical (?impedance?). I have no experience of these, believe them to be prone to inaccuracy BUT they may still work as the messenger for Steve's crowd. They would appear 'scientific'  and objective, without any personal opinion being thrown in.
They might just be available in the sales somewhere...

[border-rider]

They're worse than BMI.

The 4-contact wrist-ankle electrode ones are OK.  The stand-on ones are not.  

[Zoidburg]

I did see an article in some US magazine where they did a proper body fat test on a small test group of differing cyclists.

IIRC correctly they weighed them and then weighed them again in a plunge tank at a sport science university.

The weight difference being used to calculate actual body fat.

One of the tested guys was a small slight long distance type, comfirming what I suspected about some cyclists that do lots of miles in very spinny gears , the test said that he was underweight and that his muscles were actually starting to atrophy because of the high calorie usage, low calorie intake and the lack of proper resistance training.

[hellymedic]

These http://www.johnlewis.com/230735232/Product.aspx are on sale at John Lewis but there's a whole page of them here http://www.johnlewis.com/Search/Search.aspx?SearchTerm=body+fat+scale some rather pricy...

[hellymedic]

They're worse than BMI.

The 4-contact wrist-ankle electrode ones are OK.  The stand-on ones are not.  

Agreed.
The problem is denial, not accuracy...

[border-rider]

I did see an article in some US magazine where they did a proper body fat test on a small test group of differing cyclists.

IIRC correctly they weighed them and then weighed them again in a plunge tank at a sport science university.

The weight difference being used to calculate actual body fat.

That's one of the gold standard techniques - pretty accurate it is to. The water tank gives body volume, and from weight you can work out density and calculate fat content. 

[border-rider]

Agreed.
The problem is denial, not accuracy...

Sure, but the stand-on scales are useless at even telling if you're fat or not.  The only useful part of the information they give is how much you weigh

[andygates]

They give a trend.  But so does the mirror and the tightness of one's waistband:

Caliper %Scale %Waistband feel 14 25 Loose 17 28 Snug 20 32 Suck it in! Mind you, if you like gadgets and charts (I can't be the only one who has composition charts with special "jibbly" and "meaty" textures for the relative sections, surely?) numbers are good, hm'kay..?

[Zoidburg]

63% Buff.

Trace levels of mooby-ness?

[simonp]

I was told 18% from calipers at a sports sciencey place and the scales said 17.9.  I'll be interested to compare again next time as I've lost 3kg.

I saw some cunning device on the telly which used air volume.  This meant you didn't need to drown in order to get a fully accurate result.  Yet I also read they were shite.

Ho hum.

[Regulator]

They're worse than BMI.

The 4-contact wrist-ankle electrode ones are OK.  The stand-on ones are not.  

Agreed.
The problem is denial, not accuracy...

As an aside, my GP uses a hand held body fat monitoring thingy made by Omron...

Whether it's just for show or not I cannot say.  But he did note down the reading*.









*Which I shall not reveal...  

[simonp]

Look at the graph on page 2 of the validation report, for males.

Females seem to have much less error, interestingly.  Probably more even fat distribution in their bodies?

[border-rider]

As an aside, my GP uses a hand held body fat monitoring thingy made by Omron...

Whether it's just for show or not I cannot say.

About the same as the stand-on ones.  As Andy says, may be useful to show trends in individuals (if you control very carefully for hydration) but not much good as an absolute measurement device.

[border-rider]

Look at the graph on page 2 of the validation report, for males.

Females seem to have much less error, interestingly.  Probably more even fat distribution in their bodies?

generally a smaller range in upper body musculature.

It's basically measuring how fat your wrists and elbows are.