Waist size is better predictor of cancer risk in men than BMI

The size of a man’s waistband is a better predictor of cancer risk than traditional body mass index measurements, research has found.

For decades, doctors have relied on BMI scores to diagnose obesity and the subsequent increased risk of cancer.

But now, experts believe measuring waist circumference is a more accurate way to predict cancer risk in men and as effective as BMI in women.

Obesity is the second biggest avoidable risk factor for cancer in the UK after smoking, and it costs the NHS about £11 billion a year.

Researchers from Lund University in Malmo, Sweden, analysed the health records of 339,190 people between 1981 and 2019.

They were followed for an average of 14 years during which time 18,185 people developed obesity-related cancer, which includes cancers of the oesophagus, bowel, liver, pancreas, breast, and gallbladder, among others.

The researchers took account of other risk factors such as age and smoking status and used a standardised score for both metrics so they could be directly compared.

Men with an extra 11 centimetres – or just over four inches – on their waistlines, increased their risk of developing cancer by 25 per cent.

But a comparable increase in BMI of 3.7, such as from 24 to 27, increased the risk by 19 per cent.

The researchers said the excess abdominal body fat elevated the risk of cancer beyond the standard BMI increase.

For women, the associations were weaker and similar for both waist circumference and BMI.

It found that both a 12cm wider waistline and an increase in BMI score of 4.3, were both associated with a 13 per cent higher risk of developing cancer.

The research will be presented at this year’s European Congress on Obesity in Malaga, Spain, in May, and published in The Journal of the National Cancer Institute.

The authors said it was more accurate to measure waist circumference because BMI “does not provide information on fat distribution”.

More effective in men

They said stomach fat “accumulates around the abdominal organs” and was more likely to lead to disease, while people with similar BMI scores but different fat levels and placement, would have different cancer risks.

They said it was a more effective measure in men because they are more likely to store fat in the abdominal area, whereas women are more likely to have fat spread across their body.

Earlier this week, NHS guidelines revealed that millions of people would be summoned for annual weigh-ins at their GP surgery.

The National Institute for Health and Care Excellence (Nice), the health watchdog, said everyone with common long-term conditions including arthritis, heart failure and diabetes would have annual BMI and waist circumference checks.

The guidance covers about 15 million people in total and is aimed at preventing weight-related complications developing over time, including cancer, by ensuring that those who are putting on weight are referred to NHS services offering diet plans or weight-loss injections.

It comes after Nice told NHS medics to measure people’s waist-to-height ratio as well as BMI when diagnosing obesity.

Some scientists have argued that obesity has been over-diagnosed based on the use of BMI alone.

As part of a Lancet Commission, a global group of experts have called for obesity diagnoses to be split into two parts – pre-clinical and clinical – to distinguish between those who have bad health as a result of their weight and those who are “fat but healthy”.

The group recommended the use of a new model that would use waistband measurements, waist-to-hip and waist-to-height ratios, and direct body fat measurements, instead of just BMI.