Scientists at the International Agency for Research on Cancer (IARC), which is an arm of the World Health Organisation, have shown that waist measurement is as good at predicting cancer risk as body mass index (BMI), which is a ratio of weight to height.

An expanding waistline could be a warning sign that a man or woman is running an increased risk of certain cancers, according to international experts.

According to Dr Heinz Freisling of IARC, the lead author of a study in the British Journal of Cancer, “the increased risk of certain cancers, as well as type 2 diabetes, kicks in at a waist measurement of 102cm (40in) for men and 88cm (35in) for women.”

“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.”, he added

He advises people to know their BMI and also to measure their waistlines. “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 pancreas or liver cancer which are known to be related to increased body fatness or obesity.”

Being overweight or obese is the single biggest preventable cause of cancer after smoking and is linked to 13 types of cancer including bowel, breast, and pancreas.

The study looked at BMI, waist measurement, and waist to hip ratio to find out how good these were at predicting increased risk of obesity-related cancers.

It showed that adding about 11cm to the waistline increased the risk of obesity-related cancers by 13%. For bowel cancer, adding around 8cm to the hips was linked to an increased risk of 15%.

The study combined data from about 43,000 participants who had been followed for an average of 12 years and more than 1,600 people were diagnosed with an obesity-related cancer.