to think that BMI calculations are crap in determining if you are over/underweight?

[GetOrfMoiLand]

According to my BMI I am underweight. If you looked at me you wouldn't in a month of Sundays say I was underweight. I am fine boned that is all.

Just made me a bit annoyed because we did BMIs at the gym today (just out of boredom waiting for a class to start) after weighing ourselves - and the people I was with started saying 'ooh you're underweight' just because I number told them I was.

Differnt BMI calculation for kids and the one for adults, SHOULD NOT under any circumstances be used.

Baroness this calculation wouldn't apply to you if you are breastfeeding an infant, unless of course you are heavy all over. Most people are aware (even if they bury their head in the sand) if there's too much fat on them.

Certain situations are exempt from this calculation (big muscular athletes, pregnant women, breastfeeders, there are a few others under which this calculation would not be appropriate).

But one can be breastfeeding and still be overweight/obese and have weight in other areas that needs to come off (at some point in the future). It doesn't mean that common sense (both on the part of doctors and individiuals) shouldn't be applied because of calculating this 1 number.

Baroness, not saying your fat - just using an example of a breastfeeding woman (i've just stopped myself) who could take into consideration their BMI, when assessing their overall health.

It's one part of a group of ways to determine if you are in "good health"

you're fat rather

The only problem I see with BMI is how it's interpretted by laypeople. As a crude initial screening test it's fine, but I'm not sure if it should be used to look up charts that appear so definitive.

Boobs don't have to be on the scales to weigh them, simply get someone to hold/support them whilst you weigh yourself and then work out the difference!

It doesn't bother me that my bmi is over 25, it bothers me that I would be lumped in a category based on that figure if people don't look beyond the number.

Our kids have no chance, OH has a BMI of over 30 and whilst he carries a little excess he'd have to cut off a leg to get within range - he's built like a Viking :)

Spot on peanutbutterkid.
Knowing your BMI doesnt' really tell you an awful lot about your health, without knowing other things!

BMI measurements are based on an index originally worked out on a statistical sample of recruits for (I think) scottish and belgian armies in the mid 1800s (mostly the work of Adolphe Quetelet) eg the average male from localised western populations in a different century
the papers in the 70s popularising its use stated it was useful for assessing population trends, not for individual diagnosis but its often used without muchunderstanding of this
I have a problem with it being used in children because the way they grow eg putting on weight before gaining inches in a growth spurt means its of very limited use unless you think about where they are in this cycle in terms of their individual growth eg you could be BMI 30 before a growth spurt at puberty and 6 months later back to normal range, without any lifestyle changes and I so agree with Confused - a number or designation with no undestanding of the context or statistics is no bloody use at all to a child negociating growth, puberty and body changes!

NB although just because the statistical method is flawed doesnt mean you dont have a problem - but i suspect better indices might be fat estimation, waist to hip ratio, skin pinch tests

"BMI measurements are based on an index originally worked out on a statistical sample of recruits for (I think) scottish and belgian armies in the mid 1800s (mostly the work of Adolphe Quetelet) eg the average male from localised western populations in a different century
the papers in the 70s popularising its use stated it was useful for assessing population trends, not for individual diagnosis but its often used without muchunderstanding of this"

That is very interesting. And bloody worrying.

Since BMI in children is usually interpreted in a percentile way, doesn't that get around the temporary puppy-fat problem?

Come to think of it, wouldn't that be a better way to interpret BMI in adults, too (as percentile data)?

Although real question is, how difficult is it to do calipers body fat% calcs? Are they more accurate? And would it be better if people were simple given bands for BMI results along the lines of:

You may be too thin,
You are probably alright, and
You may want to ask your GP about your body fat levels

rather than the charts as they exist.

Yes GetOrf it is rather
As I said earlier, on a epidemiological level, it's a reasonable measure.
Not so much for an individual without taking into account other things!

But that's all they do do peanutbutterkid.

Below 18.5 - you might be too thin
Above 25 - you might be a bit big
Between the two - probably OK
Unless there is something unusual about you (giant muscley rugby player, bird-boned tiny woman, mahoosive BFing breasts, etc)

No-one is told they should aim for the middle of the range, or for the bottom end of the range as some seem to think they should.

why are you measuring a population and telling them individual diagnoses if you know theyre likely to have a puppy fat/shifting growth pattern problem though?

they dont explain to the child well, you are 90th centile but you fall within a bell curve of normal distribution for your age, instead kids get a one word snapshot diagnosis eg underweight/obese which may be true for that moment but weeks- months later could be complete irrelevent
I cant see how that helps anyone

perhaps if we had a better means of surveillence or a school nurse system we could observe kids/eating habits/exercise ability and really target information/advice to those with a problem

chicletteeth don't worry! I didn't read it as you'd said I was fat.

although I am also carrying extra weight on my thighs which needs to go

I have often wondered how much my boobs weigh (am usually F/FF, was H while breastfeeding). I am so going to try and find out now!

Oh, I thought most BMI charts were still like this. Quite blunt and simplistic. But glad to hear that more nuanced interpretations are now the norm.