This article is from the source 'bbc' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at http://www.bbc.co.uk/go/rss/int/news/-/news/health-12481427

The article has changed 14 times. There is an RSS feed of changes available.

Version 9 Version 10
Body Mass Index - BMI - 'misses obesity risks' Body Mass Index - BMI - 'misses obesity risks'
(40 minutes later)
VIEWPOINT By Dr Margaret Ashwell Visiting Fellow, Oxford Brookes University Ashwell OBEVIEWPOINT By Dr Margaret Ashwell Visiting Fellow, Oxford Brookes University Ashwell OBE
In this week's 'Scrubbing Up', nutrition expert Dr Margaret Ashwell OBE argues that using BMI alone could be missing some patients at risk of the diseases associated with obesity.In this week's 'Scrubbing Up', nutrition expert Dr Margaret Ashwell OBE argues that using BMI alone could be missing some patients at risk of the diseases associated with obesity.
BMI is calculated by dividing someone's weight in kilograms by the square of their height in metres.BMI is calculated by dividing someone's weight in kilograms by the square of their height in metres.
But because BMI is based on weight, people who are unusually muscular can have BMI values which would make them overweight or obese. Examples might include professional rowers and boxers.But because BMI is based on weight, people who are unusually muscular can have BMI values which would make them overweight or obese. Examples might include professional rowers and boxers.
Different types of fatDifferent types of fat
There's a second, even more important, problem. BMI is a good proxy for total body fat, but it cannot distinguish between different types of fat distribution.There's a second, even more important, problem. BMI is a good proxy for total body fat, but it cannot distinguish between different types of fat distribution.
Excess fat that is found deep down in the region of the stomach gives someone a large waist circumference and an 'apple' shape. This is often associated with risk factors for serious conditions such as heart disease, raised blood pressure and diabetes.Excess fat that is found deep down in the region of the stomach gives someone a large waist circumference and an 'apple' shape. This is often associated with risk factors for serious conditions such as heart disease, raised blood pressure and diabetes.
Excess fat that is found under the skin, around the bottom, hips and thighs is usually accompanied by a smaller waist circumference and a 'pear' shape. This is generally accepted to be less harmful to health.Excess fat that is found under the skin, around the bottom, hips and thighs is usually accompanied by a smaller waist circumference and a 'pear' shape. This is generally accepted to be less harmful to health.
So a measurement that can distinguish between 'apples' and 'pears' would be a more effective way of screening for these diseases.So a measurement that can distinguish between 'apples' and 'pears' would be a more effective way of screening for these diseases.
I have argued since 1996 that we should assess risk based on waist-to-height ratio (WHtR); saying that "Your waist circumference should not be more than half your height (WHtR 0.5)".I have argued since 1996 that we should assess risk based on waist-to-height ratio (WHtR); saying that "Your waist circumference should not be more than half your height (WHtR 0.5)".
This is the point at which some action to decrease your waistline should be considered.This is the point at which some action to decrease your waistline should be considered.
My colleagues and I recently published a review of 78 studies in 14 different countries, including Caucasian, Asian and Central American subjects, which has confirmed that WHtR is a better predictor of cardiometabolic risk than BMI and that WHtR 0.5 is a suitable boundary value.My colleagues and I recently published a review of 78 studies in 14 different countries, including Caucasian, Asian and Central American subjects, which has confirmed that WHtR is a better predictor of cardiometabolic risk than BMI and that WHtR 0.5 is a suitable boundary value.
Simple risk assessmentSimple risk assessment
The WHtR measurement offers the exciting possibility that it could be used to assess risk for adults in several ethnic groups. This is because the BMI boundary values were derived from Caucasian populations.The WHtR measurement offers the exciting possibility that it could be used to assess risk for adults in several ethnic groups. This is because the BMI boundary values were derived from Caucasian populations.
They might not be appropriate for Asians, who tend to carry more fat centrally so their risk seems to increase at a BMI lower than 25 (between 20 and 25 is considered a healthy BMI).They might not be appropriate for Asians, who tend to carry more fat centrally so their risk seems to increase at a BMI lower than 25 (between 20 and 25 is considered a healthy BMI).
WHtR might also be a simple way to assess health risk in children.WHtR might also be a simple way to assess health risk in children.
And of course waist circumference and height can be measured with a simple tape measure in any units: inches, centimetres etc, unlike the BMI which requires weighing scales and must be expressed in metric units.And of course waist circumference and height can be measured with a simple tape measure in any units: inches, centimetres etc, unlike the BMI which requires weighing scales and must be expressed in metric units.
The public health message is simple - "keep your waist circumference to less than half your height".The public health message is simple - "keep your waist circumference to less than half your height".
Missing the risksMissing the risks
So what would be the difference in screening for central obesity using WHtR, instead of screening for total obesity using BMI?So what would be the difference in screening for central obesity using WHtR, instead of screening for total obesity using BMI?
In 2009 we published a paper in which we applied the WHtR boundary value of 0.5 to nearly 2,000 British adults in the nationally representative National Diet and Nutrition Survey.In 2009 we published a paper in which we applied the WHtR boundary value of 0.5 to nearly 2,000 British adults in the nationally representative National Diet and Nutrition Survey.
We found that one in three 'non-overweight' men (judged by a BMI of 25 or less) and more than one in seven 'non-overweight' women had a WHtR value greater than 0.5.We found that one in three 'non-overweight' men (judged by a BMI of 25 or less) and more than one in seven 'non-overweight' women had a WHtR value greater than 0.5.
So these people may, unknowingly, be at increased risk of serious conditions such as heart disease and diabetes, due to their central obesity.So these people may, unknowingly, be at increased risk of serious conditions such as heart disease and diabetes, due to their central obesity.
These are the 'non-overweight apples'.These are the 'non-overweight apples'.
On the other hand, one in six women and one in twenty men who were told they were overweight by BMI assessment, would actually have relatively low cardiometabolic risk because their WHtR is 0.5 or less.On the other hand, one in six women and one in twenty men who were told they were overweight by BMI assessment, would actually have relatively low cardiometabolic risk because their WHtR is 0.5 or less.
These are the 'overweight pears'.These are the 'overweight pears'.
Most interesting of all, the 'non-overweight apples' had significantly higher levels of cardiometabolic risk factors (blood pressure and non-HDL cholesterol) than the 'overweight' pears'.Most interesting of all, the 'non-overweight apples' had significantly higher levels of cardiometabolic risk factors (blood pressure and non-HDL cholesterol) than the 'overweight' pears'.
It is a real worry that using BMI alone for screening could miss people who are at risk from central obesity and might also be alarming those whose risk is not as great as it appears from their BMI.It is a real worry that using BMI alone for screening could miss people who are at risk from central obesity and might also be alarming those whose risk is not as great as it appears from their BMI.


Comments



Comments

You are not currently signed in. or register.You are not currently signed in. or register.
 
 
This comment is awaiting moderation. href="http://www.bbc.co.uk/blogs/moderation.shtml#appear" target="_blank">Explain. I am glad to hear this as I have been saying this as a patient to my health care providers, but instead have been sent away as those I'm not making sense. I'm glad that some of the comments here support what I say. BMI is indeed "outdated" and "lazy" way that the NHS use.In conclusion I support below that "there are lies, damn lies, and BMI's ". ;) currently in the NHS.
Report this comment Report this comment
Link to thisLink to this
    		•
    • I'm a 24 y/o male Personal Trainer and my BMI is 26 yet i do lots of weight training which increses my muscle size + density yet i am told by other ''Health Professionals'' i need to get my BMI down.I am in total agreement that BMI is an outdated and in my opinion lazy way to determin if someone is Obese. Better testing would be Waist to Height and a scientific method of body fat % testing.I'm a 24 y/o male Personal Trainer and my BMI is 26 yet i do lots of weight training which increses my muscle size + density yet i am told by other ''Health Professionals'' i need to get my BMI down.I am in total agreement that BMI is an outdated and in my opinion lazy way to determin if someone is Obese. Better testing would be Waist to Height and a scientific method of body fat % testing.
    Report this comment Report this comment
    Link to thisLink to this
    		•
    • my BMI is 21. however i know for a fact that i am underweight and under-eat and always have done. now it shows im a perfect weight but i eat 1 small meal a day as its all i can afford and a top of that i have always been so skiny you can see my ribs clearly. thats not healthy... it misses both ends of the scale, plus what about the fact that a english BMI is different to a asian BMI?my BMI is 21. however i know for a fact that i am underweight and under-eat and always have done. now it shows im a perfect weight but i eat 1 small meal a day as its all i can afford and a top of that i have always been so skiny you can see my ribs clearly. thats not healthy... it misses both ends of the scale, plus what about the fact that a english BMI is different to a asian BMI?
    Report this comment Report this comment
    Link to thisLink to this
    		•
    • My BMI is 30.6. My WHtR is just under 0.5. My fasting blood glucose, resting heart rate, blood cholesterol are perfect for someone half my age (I am 40). I battle against low blood pressure. I am muscular and work out 4 times a week. Most of my underweight female friends are pre-diabetic and infertile following years on low fat diets. I wouldn't change places for the world.My BMI is 30.6. My WHtR is just under 0.5. My fasting blood glucose, resting heart rate, blood cholesterol are perfect for someone half my age (I am 40). I battle against low blood pressure. I am muscular and work out 4 times a week. Most of my underweight female friends are pre-diabetic and infertile following years on low fat diets. I wouldn't change places for the world.
    Report this comment Report this comment
    Link to thisLink to this
    		•
    • @reggiedixon, in fact obesity remains as hotly debated as climate science, however the media (as always) insist on only reporting the side of it which supports their fat panic narrative. Articles like those linked below, published in respectable journals, suggest that the science is far from 'settled'. http://www.nutritionj.com/content/10/1/9http://ije.oxfordjournals.org/content/35/1/55.full@reggiedixon, in fact obesity remains as hotly debated as climate science, however the media (as always) insist on only reporting the side of it which supports their fat panic narrative. Articles like those linked below, published in respectable journals, suggest that the science is far from 'settled'. http://www.nutritionj.com/content/10/1/9http://ije.oxfordjournals.org/content/35/1/55.full
    Report this comment Report this comment
    Link to thisLink to this
       
    Comments 5 of 10Comments 5 of 10
       
    Add your commentAdd your comment
    You are not currently signed in. or register.You are not currently signed in. or register.