Waist size can predict your risk of certain cancers, according to a World Health Organisation report published in the British Journal of Cancer.
Researchers compared BMI, waist measurement, and waist to hip ratio to find out which was the most reliable predictor. They found that waist size was at least as useful as body mass index (BMI), the ratio of weight to height.
Waist measurement can be a more useful indicator of cancer risk than BMI because it is closely correlated with levels of ‘visceral fat’, or abdominal fat, which is known to increase cancer risk.
The study shows that an 11cm (4.3 inch) increase in waist size increases the average risk of 13 obesity-related cancers (including kidney, breast and bowel cancer) by 13 per cent. Just 8cm extra — that is, about three inches — increases the risk of bowel cancer by 15 per cent.
The researchers, from the WHO’s International Agency for Research on Cancer, looked at data gathered from 43,000 study participants followed for an average of 12 years. In that time over 1,600 of them were diagnosed with an obesity-related cancer.
Dr Heinz Freisling, the study’s lead author, said: ‘You only need to put a tape measure around your belly button. This is easy to do and can give a person an indication of whether their risk for specific cancers is increased or not – for instance, [for] pancreas or liver cancer, which are known to be related to increased body fatness or obesity.
‘Our findings show that both BMI and where body fat is carried on the body can be good indicators of obesity-related cancer risk. Specifically, fat carried around the waist may be important for certain cancers, but requires further investigation.
‘To better reflect the underlying biology at play, we think it’s important to study more than just BMI when looking at cancer risk. And our research adds further understanding to how people’s body shape could increase their risk.’
Most people are well aware that being overweight causes significant long-term health risks. Indeed it is the single biggest preventable cause of cancer after smoking.
Conventional advice is often to measure the body mass index (BMI) but this study suggests that measuring waist size may be a better marker for potential cancers. It found that an increased risk of certain cancers and type-2 diabetes developed at a waist measurement of 40 inches (102cm) for men and 35 inches (88cm) for women. It showed that adding 11cm to the waistline increased the risk of obesity-linked cancers by 13 per cent and, for bowel cancer in particular, adding around 8cm to the hips was linked to an increased risk of 15 per cent.