Obesity could cause as many cancers as smoking, health experts warn today.

Cancer Research UK say Britain’s obesity epidemic is the biggest risk to health.

They say millions of people are putting their lives at risk because they are unaware that a bad diet and lack of exercise can increase their risk of developing cancer.

Professor Jane Wardle, director of Cancer Research UK’s Health Behaviour Unit, said recent studies had established a link between obesity and cancer, especially cancer of the breast, womb, kidney, bowel and oesophagus.

She said: “Obesity is probably as big a risk as smoking when it comes to cancer and obesity rates are climbing, whereas thankfully smoking rates are declining. It means we have a timebomb to come.”

Low awareness of cancer risk

The charity today published a poll by NOP revealing that just three per cent of Britons recognise that being obese increases their chances of developing cancer.

At the moment 270,000 new cases of cancer are diagnosed a year in the UK - one third of them linked to smoking.

Professor Wardle warns that Britain is following American trends where one third of cancers are due to smoking and an equal number are attributed to obesity.

She said: “The tide of obesity-related disease is going to take over health spending. Unless we can do something to arrest the trends, obesity is going to be the biggest risk to population health at the beginning of this century.”

Government concerns

Today’s study comes after government concerns over Britain’s growing obesity epidemic led to calls for a ” fat-tax” on junk food and fizzy drinks.

One in three adults will be diagnosed with cancer during their lifetime. And one in five men and almost one in four women are obese - projected to rise to 40 per cent of all adults in the next generation.

Professor Wardle said: “We have engineered physical activity out of our lives as much as possible and at the same time the change in food means we over-eat.

“It is undoubtedly true that many people who are obese and overweight are not really aware that they have got a problem.”

She said society tends to focus on the aesthetics of being overweight rather than on the health risks.

Prof Wardle said: “Excess body fat is not harmless extra padding, but active tissue producing hormones that can increase the risk of cancer.

“We also know people who eat low amounts of fruit and vegetables are at risk from obesity and also cancer.”