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Body shape is still important to heart disease risk
by Matthew - Tuesday, 15 March 2011, 11:12 AM
 
Body shape is still important to heart disease risk

The news media havePear-shaped recently reported that body shape, as measured using waist-to-hip ratio, is no longer considered to be a good predictor of cardiovascular disease risk. This conclusion was drawn from a study published in the Lancet last week, which examined data from 58 trials involving 222,000 people in 17 countries across Europe.

The Daily Mail wrote: “A medical U-turn has cast doubt on warnings that being overweight and 'apple-shaped' is especially dangerous to the heart”. Taken at face value, this is not an accurate summary of the findings.

What the Lancet study found is that people with a high waist-to-hip ratio are more likely to develop cardiovascular disease (CVD), but this measure is just as good as body mass index (BMI) and waist circumference in predicting risk and doesn't improve risk prediction when other measurements, such as blood pressure, history of diabetes and blood lipids are also available. So being overweight and apple-shaped is still a risk to health, but it's no better than body mass index (BMI) at predicting your chances of developing cardiovascular dieases (CVDs).

What’s the value of waist-to-hip ratio?

Waist-to-hip ratio (WHR) provides a measure of whether you're, relatively speaking, “apple-shaped” or “pear-shaped”. WHR is calculated by measuring the circumference around your middle (just above your belly button) and dividing this figure by the circumference around your hips (at the widest part of your buttocks). The higher your WHR, the more "apple-shaped" you are. Along with body mass index (BMI) and waist circumference, WHR indicates how much fat you have in your body. Having a lot of body fat (high adiposity) increases your risk of developing heart disease (i.e. having a heart attack) as well as having a stroke.

Furthermore, several studies had shown that people with "apple-shaped" bodies (with more weight around their waist) face more health risks than those with "pear-shaped" bodies (who carry more weight around the hips). Some studies have found that overweight people with "apple shaped" bodies are three times more likely to suffer heart attacks than those with more generally distributed fat.

What does this new study show us?

The new study, published in the Lancet, was carried out by researchers from the University of Cambridge, funded by the British Heart Foundation and UK Medical Research Council.

The study involved a systematic review of patient data from 58 different study populations. The aim was to examine how BMI, waist circumference and waist-to-hip ratio are linked to the development of cardiovascular disease and to explore the relationship between these measures and conventional risk factors (e.g. high blood pressure).

What did they find? BMI, waist circumference and waist-to-hip ratio were all independently associated with an increased risk of fatal or non-fatal coronary heart disease and stroke. However, adding these measures into risk prediction models based on conventional risk factors (for example smoking, diabetes, blood pressure and bad cholesterol) did not alter heart disease and stroke risk estimates. This means that none of the body measures listed, individually or in combination, could improve risk prediction when information on other risk factors was available.

Furthermore, on it's own, WHR is not significantly better than BMI or waist circumference at predicting CVD risk. What the news media latched on to was the idea that being "apple-shaped" is no worse than being "pear-shaped" (as measured by BMI). What the the study actually found is that an increase in any one of WHR, BMI or waist circumference are equally and independently associated with an increased risk of cardiovascular diseases. So being overweight and "apple-shaped" is still a risk to health.

What do we say?

High body fat puts you at greater risk of developing heart disease and stroke. BMI, WHR and waist circumference are all equally as good at predicting risk, in terms of whether you’re in the low, medium or high risk category. If you want a more accurate measure of your risk of developing these diseases, go to your doctor, who will do a blood test and assess your lifestyle and medical history.

Sources: The Lancet, Early Online Publication, 11 March 2011.
"Body shape 'still important to heart risk'". NHS Choices (http://www.nhs.uk/news)


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