Weight link to cancer warning

27 May 2008 12:10am

People at the top of their healthy weight range are more likely to develop bowel and breast cancer than those at the bottom of it, an expert warned.

Professor Martin Wiseman, medical and scientific adviser to the World Cancer Research Fund, said more needed to be done to get the message across that even people who thought they were a healthy weight could be putting themselves at risk.

He said somebody with a BMI of 25 had about a 15% higher risk of bowel cancer and women had around a 7% higher risk of post-menopausal breast cancer than a person with a BMI of 20.

Body mass index (BMI) can be worked out by taking a person's weight in kilograms (kg) and dividing it by height in metres. The result should then be divided by height in metres again.

If the resulting BMI is between 18.5 and 24.9, the person is the ideal weight for their height. If it is between 25 and 29.9, the person is overweight while between 30 and 39.9 is obese and over 40 is very obese. As well as breast and bowel, there is convincing evidence that excess body fat can cause cancer of the oesophagus, pancreas, kidney and womb.

Prof Wiseman said the WCRF recommended that people aimed to keep towards the lower end of their healthy weight range.

"It is not widely appreciated, but the evidence is clear that even within the healthy weight range being fatter increases risk of several types of cancer," he said.

"This is why we recommend that people aim to be as close as possible to the lower end of the healthy range. There is convincing evidence that excess body fat is a cause of six different types of cancer and the fatter you are, the higher your risk.

"This is a real cause for concern when you consider that as a nation we are becoming increasingly overweight. But the good news is that maintaining a healthy weight is something positive that people can do to reduce their risk of developing cancer in the future. And for people who are already overweight, then it seems likely that they can reduce their risk by losing weight."

Scientists now believe that after not smoking, maintaining a healthy weight is the most important thing people can do to prevent getting cancer.

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