Is BMI living in the real world ?

[loggo]

I have issues with the Body Mass Indicator scale

I am 5 feet 11 inches toll, 32 waist and M for teashirts, 38-40 chest. Generally considered far from overweight

However if I Check my BMI I am a whisker under 23.5.

Overweight begins at 25 and I would be in the "ideal" section down to 18.5 (which would see me at 9 stones 7 lb)

Surely this is just too extreme ?

Edited by loggo on Monday 8th March 09:22

[craigjm]

It’s just a general guideline but seems to be taken by many as gospel. Your healthy weight is about more than just height to weight and can vary significantly based on your sex, age, ethnicity and other things. You could put on some muscle from where you are now and your BMI would be over. If you’re happy with your weight and diet etc I wouldn’t worry about it.

[loggo]

craigjm said:

It’s just a general guideline but seems to be taken by many as gospel. Your healthy weight is about more than just height to weight and can vary significantly based on your sex, age, ethnicity and other things. You could put on some muscle from where you are now and your BMI would be over. If you’re happy with your weight and diet etc I wouldn’t worry about it.

I appreciate that it's a guideline and I am quite content with my position. My concern is that the scale seems completely skewed. For instance if I increased my waist size to 36 I would be well overweight but if I decreased to the size of a telegraph pole (Diameter not height !) I would be within tolerance

[craigjm]

loggo said:

I appreciate that it's a guideline and I am quite content with my position. My concern is that the scale seems completely skewed. For instance if I increased my waist size to 36 I would be well overweight but if I decreased to the size of a telegraph pole (Diameter not height !) I would be within tolerance

I guess it’s more concerned with identifying those as 30 plus than it is anyone else. If I put in my height it tells me that I would be within tolerance at 9st 3. I would look like a skeleton but I guess it doesn’t become medically dangerous until I’m under 9 stone and therefore “underweight”

Body fat percentage is a better mechanism as you can allow for age, ethnicity, sex etc

[leef44]

loggo said:

I have issues with the Body Mass Indicator scale

I am 5 feet 11 inches toll, 32 waist and M for teashirts, 38-40 chest. Generally considered far from overweight

However if I Check my BMI I am a whisker under 23.5.

Overweight begins at 25 and I would be in the "ideal" section down to 18.5 (which would see me at 9 stones 7 lb)

Surely this is just too extreme ?

Edited by loggo on Monday 8th March 09:22

Agreed, that does seem extreme. I guess it's trying to over compensate for the obesity problem we have in this country but could be dangerously misconstrued by those who are underweight or have eating disorders.

[Foliage]

ignore BMI, its a substitution for the nearly impossible to accurately measure percentage body fat.

Im overweight/obese on BMI but really im not, coz all the weight is in my shoulders, thighs and chest.

They should really convert over to waist & chest vs height by ethnicity.

[croyde]

loggo said:

I have issues with the Body Mass Indicator scale

I am 5 feet 11 inches toll, 32 waist and M for teashirts, 38-40 chest. Generally considered far from overweight

However if I Check my BMI I am a whisker under 23.5.

Overweight begins at 25 and I would be in the "ideal" section down to 18.5 (which would see me at 9 stones 7 lb)

Surely this is just too extreme ?

Edited by loggo on Monday 8th March 09:22

I'm the same build as you, pretty athletic luckily yet hover on the upper limit of BMI.

I lost 5kg due to a stressful period but then I had good BMI yet everyone said I looked gaunt and far too thin.

[Prof Prolapse]

loggo said:

I appreciate that it's a guideline and I am quite content with my position. My concern is that the scale seems completely skewed. For instance if I increased my waist size to 36 I would be well overweight but if I decreased to the size of a telegraph pole (Diameter not height !) I would be within tolerance

I think you're over thinking it mate, as said above, it's based just on your height and weight, not composition.

It's also a range, for you that low level weight may make you deathly ill, but others will be fine.

So as long as you're in the range, for the most part you're accounting for most body shapes and compositions, so all is well.

BMI works great, it's backed up by masses of data for that reason, just don't overthink it!

[didelydoo]

It’s a great indicator for the vast majority of the population. There are outliers, but, not a whole lot.

[Prof Prolapse]

didelydoo said:

It’s a great indicator for the vast majority of the population. There are outliers, but, not a whole lot.

You see this is exactly it. For me the objectors fall in three camps;

(1) Those who don't understand it's a range of an average, not a lower is better scenario.

(2) Those who have worked hard to have an extreme body shape, then don't understand that being an extreme means you're no longer average.

(3) Fat blokes in denial. This is the overwhelming majority.

[Dogwatch]

From Wikipedia:

Carl Lavie has written that, "The B.M.I. tables are excellent for identifying obesity and body fat in large populations, but they are far less reliable for determining fatness in individuals."

https://en.m.wikipedia.org/wiki/Body_mass_index

[ORD]

The range is where it is because most people have very little muscle mass. If your BMI is 25 and you're not reasonably muscular, you are fat.

[Burrow01]

croyde said:

loggo said:

I have issues with the Body Mass Indicator scale

I am 5 feet 11 inches toll, 32 waist and M for teashirts, 38-40 chest. Generally considered far from overweight

However if I Check my BMI I am a whisker under 23.5.

Overweight begins at 25 and I would be in the "ideal" section down to 18.5 (which would see me at 9 stones 7 lb)

Surely this is just too extreme ?

Edited by loggo on Monday 8th March 09:22

I'm the same build as you, pretty athletic luckily yet hover on the upper limit of BMI.

I lost 5kg due to a stressful period but then I had good BMI yet everyone said I looked gaunt and far too thin.

Problem is that being overweight is now normalised, if you look at pictures from the 50's,60's and 70's you can see peoples ribs and they are generally much thinner than the general population today. My dad was 10 stone when he joined the Marines @ 17 and 12 stone when he left (5' 8")

At the bottom end of the scale I would not be too worried about what your BMI is. At the top end people tend to say that BMI is not accurate because they don't want to believe they are obese. Unless you look like a pro rugby player, BMI is a reasonable guide.

The medical professions still use BMI as the measure of obesity and it corelates with known issues from being overweight - Diabetes, Heart Disease and recently implications from Covid.

[bigandclever]

BMI isn’t designed for individuals; it’s a mass population measure.

[Rutter]

I'm 29.9 just creeping under obese, I'd agree I'm overweight though but nowhere near to being obese. Being 6'5 skews my results a fair bit though.

Must be my powerful build...

[ORD]

I also think people dramatically underestimate their body fat percentage. At the start of this year, I was 88.5kg and looked fairly lean (visible abs). I have lost 4kg and look pretty much identical, maybe a touch leaner on thighs and shoulders. That was very likely 4kg of almost pure fat (5% of bodyweight). So despite looking lean, I was probably at 16% body fat. That isn't great. A lot of people who think they are 15% are really 20%. Those who think they are 20% are probably 30%.

[dave_s13]

bigandclever said:

BMI isn’t designed for individuals; it’s a mass population measure.

I've come round to this way of thinking. A bit like how measurement and treatment of cholesterol is treatment of statistics and not of individuals.

You never see a "big boned" skeleton do you.

[Roger Irrelevant]

Dogwatch said:

From Wikipedia:

Carl Lavie has written that, "The B.M.I. tables are excellent for identifying obesity and body fat in large populations, but they are far less reliable for determining fatness in individuals."

https://en.m.wikipedia.org/wiki/Body_mass_index

This is my understanding of it; in itself knowing the BMI of one person doesn't tell you a lot about that person. If it's over 25 then there is an increased likelihood that they are unhealthily overweight, but you're a long way from being certain enough about that to start prescribing corrective measures. If on the other hand the average BMI of one million people is over 25 then you can be pretty sure that there too many fatties about and it's time to think about public health measures to do something about it. What Burrows said above is so true though, unfortunately being overweight has become so normalised that people with BMIs above the ideal range and who are genuinely overweight can just say 'well I'm just the same as most people so BMI's a load of rubbish innit'.

[craigjm]

Rutter said:

Being 6'5 skews my results a fair bit though.

How?

[Rutter]

craigjm said:

Rutter said:

Being 6'5 skews my results a fair bit though.

How?

Due to the nature of the calculations being weight divided by height squared it leads to those that are shorter being told they have a lower BMI and those that are taller told they are higher, there are many better calculators than classic BMI.