Losing weight can reduce the risks of cancer

The NOP poll of 1,000 people for Cancer Research UK also found that 30% do not know that being overweight increases the risk of heart disease.

The findings were published to mark the launch of the charity's Race for Life.

More than 325,000 women are expected to take part in the 5km event at 150 venues across the UK on 25 July to raise money for research.

Studies have shown that being overweight or obese can increase the risks of a range of cancers.

These include cancer of the breast, womb, kidney, bowel and oesophagus.

'Worrying findings'

Experts said they were concerned at the survey's findings.

"The results of this survey are extremely worrying especially as being overweight is the major preventable risk factor for cancer in non-smokers," said Dr Lesley Walker, director of cancer information at Cancer Research UK.

The results of this survey are extremely worrying Dr Lesley Walker, Cancer Research UK Are you overweight?

Professor Jane Wardle, director of the charity's health behaviour unit, said losing weight can reduce the risks of developing cancer.

"Excess body fat is not harmless 'extra padding' but active tissue producing hormones that can increase the risk of cancer.

"In order to lose weight and then maintain a healthy body weight you need to eat less and be more active.

"Even small weight losses have been shown to have a beneficial effect on health."

Former Olympic athlete Sally Gunnell urged women to take part in the upcoming Race for Life.

"Cancer Research UK's Race for Life is a perfect starting point for those who are need to exercise or who have weight to lose.