OVERWEIGHT
Why these average Britons are ALL classed as being...
Do you know your Body Mass Index (BMI)? Are you worried that your reading is unhealthily high? Then you might be worrying unnecessarily, especially if you are a traditional ‘pear’ shape (with a small waist but big hips) or take exercise.
BMI is the most widely used method for assessing whether people are a healthy weight. It’s calculated by dividing your weight in kilograms by your height in metres, and dividing the answer by your height again — it might be easier to use a BMI chart or an online calculator.
Typically, a BMI below 18.5 is regarded as underweight, anything between 18.5 to 24.9 is ‘healthy’, 25 or over is ‘overweight’ and 30 or more is categorised as ‘obese’.
The greater your BMI, the greater the risk of conditions such as diabetes and heart disease. The average BMI for a man in the uK is 27; for a woman 26.9. Which means many of us are officially overweight and at risk. or are we?
BMI, which was first used in 1832, is now entrenched in healthcare, used for diagnosing anorexia, for instance, and to calculate life assurance premiums. It’s also key to official guidelines for treatment — for example, who qualifies for gastric surgery on the NHS.
But many experts now agree that BMI is flawed. With obesity levels spiralling, the concern is that it is not an accurate predictor of future health: people can be at risk of disease, and yet have a normal BMI, which gives them false hope, explains Dr David Haslam, a GP and chair of the National obesity Forum.
‘What worries us is that people may slip through the net and escape treatment,’ he says.
one major problem is that BMI doesn’t distinguish between muscle and fat. But muscle weighs more, so someone with a high proportion of muscle may rate as overweight or even obese.
‘Someone can have a BMI of 30 or even 35 and be fit as a flea,’ says Dr Haslam. ‘They may end up being told they are overweight, when their high BMI is down to all the physical activity they do.’
BMI also doesn’t consider where fat is distributed, even though this is crucial in predicting health outcomes.
‘Apple’ shapes, who carry fat around their middle (but may be relatively slim elsewhere), have been shown to be at raised risk of diabetes and heart disease. That’s because excess fat in and around organs such as the liver seem to release harmful compounds.
And yet using the BMI calculation, people with this body type could end up being classified as healthy. Meanwhile ‘pear’ shapes may be labelled officially ‘ overweight’, despite the fact that fat stored around the hips, bottom and thighs is safer.
Another criticism is that different thresholds are needed for different ethnic minority groups.
People of Asian, African and Caribbean descent are more prone to diabetes and heart disease, partly because they tend to store fat centrally, and so the ‘overweight’ BMI threshold should be lowered for these groups to 23, and the ‘obese’ threshold to 27.5.
But i f BMI i s an inaccurate measure of your health risks, what’s the alternative?
There may be several, according to an authoritative study by LudwigMaximilians university, Munich, in 2010 which followed more than 10,000 people over eight years.
THe researchers reported that three measurements — waist circumference, or waist-to-hip ratio or waistto-height ratio — were each better predictors of cardiovascular risk and death than BMI.
The waist-hip ratio is calculated by dividing your waist size by your hip size — in either inches or centimetres. A ratio of 1.0 or more in men, or 0.85 or more in women, suggests an apple shape, meaning a raised risk of future health problems.
The waist-height ratio is calculated by dividing your waist by your height in inches. For example, a 5ft 5in woman with a 32in waist would have a ratio of 0.49.
A ratio above 0.5 means you need to take action now (if it’s below 0.4, you shouldn’t lose more weight).
The researchers found the waistheight ratio was the best measure of all.
More recently, researchers from the Medical Research Council reported that waist size was a strong predictor of the risk of type 2 diabetes, regardless of a person’s BMI.
They f ound that overweight people with a large waist — more than 40 in for men, 34.5 in for women — had a similar risk of diabetes as obese people.
Although not advocating replacing BMI as a ‘core health indicator’, the researchers said measuring waist size in overweight patients would better help identify those at highest risk.
To measure your own waist, find the bottom of your ribs and the top of your hips, then measure half way between these, usually around the belly button (note: this may not necessarily be your narrowest point).
one of the most vocal critics of BMI is Dr Margaret Ashwell, a leading obesity and nutrition researcher at City university London. She believes that the best — and simplest — way of assessing health is to work out your waist-height ratio.
This method is more likely to detect the at-risk apple shape and is a more reliable indicator than waist circumference alone, she says, as that fails to take into account height (a bigger waist size may be healthy in a very tall, broad person).
The waist-to-hip ratio is ‘not bad at identifying apples and pears’, she adds, but ‘it doesn’t help much when people lose weight, because they’ll tend to lose some off their waist and some off their hips, so the ratio won’t change’.
Dr Ashwell says the key is to ensure your waist measurement is less than half your height. The easiest way to check this is to measure your height with a piece of string, then fold that in half and check it fits comfortably round your waist. This method works regardless of gender or ethnicity.
In a recent study involving nearly 3,000 people aged 16 and older, she found that more than a third of those with a ‘normal’ BMI would have been classed as at risk by the string method. ‘We’ve got to discover these apple- shaped people as early as we can to help them take preventative action,’ she warns.
To show just how misleading BMI can be, we looked at four people who all have the uK BMI average of 27, which makes them officially ‘overweight’ (we also looked at how they fared on the other measures). They then gave their own verdicts on being
i n this BMI category, and Dr Ashwell assessed the results. Michaela Britton, 27, lives in leeds with her husband and three children aged six, four and seven months. height, 5ft 5in; weight, 11 st 12lb; waist, 38in; hips, 42in BMi: 27, overweight Waist-hip ratio: 0.9, unhealthy Waist-height ratio: 0.58, unhealthy
Before having children I weighed 9½ st, was a size 10 and never worried about my weight. I lost weight quite easily after my first two babies, but this time I’ve put on almost a stone.
With three little ones, it’s hard to do any exercise. I generally eat well — a sandwich at lunch and shep‑ herd’s pie for dinner or quiche with salad. But I sometimes crack into chocolate in the evenings.
It wasn’t a shock to see that my BMI is ‘overweight’. When my baby is bigger, I’ll be able to do some‑ thing about it.
DR ASHWELL SAYS: Michaela’s waist‑hip and waist‑height ratio show her to be an apple shape, and this is worrying as she’s such a young age.
This is a case where BMI, which puts her at ‘overweight’, is proba‑ bly accurate. even if you’re a natu‑ ral apple shape, and it runs in your family, it’s no safer; you should still reduce fat around the middle.
Michaela might, in the future, be at raised risk of developing prob‑ lems such as diabetes. However, it’s worth remembering that the waist‑height ratio is only one of many factors we can use to make predictions for health — family history is so important, too. olly clark, 30, an army officer, splits his time between Devon and london where he lives with his girlfriend. height, 6ft 3in; weight, 15st 12lb; waist, 36in; hips, 44in BMi: 27, overweight Waist-hip ratio: 0.8, healthy Waist-height ratio: 0.48, healthy
HAvIng been in the Army for seven years, I know I’m very fit and healthy. I play lots of sports and am now in training to row the Atlantic ocean for charity.
We’ll be burning 6,000‑7,000 calories a day. So, in preparation, I’m actually trying to put on wei gh t , whi c h would take my BMI even higher.
I know that BMI can create some odd results because it does not distinguish between fat and muscle.
Some of my col‑ leagues are short and muscly, so their BMI classi‑fies them as over‑ weight. But you only have to look at how they perform, and at their blood pressure and waist size, to know they’re not overweight.
I’m not remotely bothered by my BMI: I can’t pinch an inch, and as long as I can perform in sport and at work, I don’t need to worry. DR ASHWELL SAYS: olly is a fit young man and his high BMI is probably all due to muscle. I expect that everyone in this year’s rugby World Cup will have an ‘overweight’ or even ‘obese’ BMI.
olly’s waist‑height ratio — 0.48 — is fine: it’s only when it hits 0.5 that we start to worry. And his waist‑hip ratio is also healthy. He should take no notice of his BMI. olly will be rowing the atlantic to raise money for Prostate cancer Uk and aBF, the Soldiers’ charity. to sponsor him go to atlantic-row.com
PEAR-SHAPED HEALTHY EATER
ManDy harroW, 55, is divorced with two children. She lives in north yorkshire and works in catering. height, 5ft 7in; weight, 12st 8lb; waist, 33in; hips, 43in. BMi: 27, overweight. Waist-hip ratio: 0.77, healthy. Waist-height ratio: 0.49, healthy/ borderline at risk. I’ve never been skinny, but I’ve always been fit and strong. I used to be a professional dancer and I was Miss Scarborough in 1979, so I’m quite muscular.
I go to the gym twice a week and walk at least 30 minutes a day. I also eat lots of fruit and veg, and don’t drink or smoke.
I’d always been 10‑11st until I hit my 40s and my weight slowly crept up. A few years ago I did Slimming World and went down to 11 st, and recently I was quite successful on the 5:2 diet.
Bit by bit, though, I put it back on. Chocolate and cake are my vices!
I had a BMI check at the gym once and was shocked at how high mine was, but the instructor said it was probably because I’m quite muscly.
I know I need to l ose some weight and would like to reduce my tummy, but I don’t think I’m grotesque. DR ASHWELL SAYS: All women, even those who start off pear‑shaped, will start to store fat around the middle, particularly in the lead up to and after the menopause. The change in hormone levels can alter where fat is stored.
Mandy’s waist‑height ratio is on the borderline of the ‘ take care’ category, but her waist‑hip ratio looks oK and she is still a pear‑ shape really.
This, and her desire to keep fit, should help her stay healthy. She’s done well to get to her age without gaining too much weight around the middle, but she should take care not to gain any more.
It’s arguably much more important to pick up the ‘young’ apples — but BMI wouldn’t always spot these people. So, regardless
MOTHER BATTLING THE BABY BULGE ARMY OFFICER WHO’S ROWING THE ATLANTIC
of their BMI, all women should do a quick check of their waist-height ratio using a tape measure or piece of string.
MARATHON RUNNER
Rachael GallaGheR, 31, is a primary school teacher, from lambeth, South london. height, 5ft 3in; weight, 11st 2lb; waist, 30in; hips, 42in BMI: 27, overweight Waist-hip: 0.71, healthy Waist-height ratio: 0.47, healthy I’VE LOST nearly 2st in the past 18 months, going from a size 16 to a 12. My weight had always yo-yoed. When I turned 30, I decided the longer I left it the harder it would be.
My real goal was to be fitter, but I also knew being overweight is bad for health and that if I was going to have children, I’d be at greater risk of difficulties.
So I started running. I did the London Marathon this year and still run 25 miles a week. I cycle everywhere as well — up to 30 miles a week — go to the gym twice a week and eat healthily.
I’ve still got a big bottom, but I’ve always had that shape. I’m not claiming to be thin, but I’m adamant I’m healthy. Even so, I’ve had GPs tell me my BMI is ‘overweight’, which is frustrating.
DR ASHWELL SAYS: Rachael should be proud of her shape. Her waist-height ratio is fine, and she should not worry about her big bottom because that is ‘healthy’ fat.
It’s a shame that some GPs aren’t educated enough to know that a high-ish BMI of 27 can be perfectly OK, either in the case of a tall, muscly man or someone like Rachael, who is pear-shaped and can afford to carry a bit more weight overall t han s omeone apple-shaped.
I worry for young people — there must be a lot of teenage ‘pears’ going round who are pushed into losing weight as a result of their BMI, and could be at risk of developing an eating disorder.