Forty percent of cancers can be prevented through a healthy diet and regular exercise
An expert is warning that soaring obesity rates have saddled Britain with a "cancer timebomb".
Urgent action is needed to avert a massive increase in the number of cancer cases, according to Dr Greg Martin.
Research shows that up to 40% of cancers can be prevented through a healthy diet and regular exercise, he said.
Dr Martin, science and research manager at the World Cancer Research Fund, said: "People getting fatter will lead to an increase in the number of cancer cases as surely as night follows day. You also have to add into the mix that cancer is largely an older person's disease, and the UK has an ageing population.
"So if you have an ageing population that is getting more obese, there could be really serious consequences in terms of the number of people getting cancer if people do not act now. It's a cancer timebomb."
In 2003, an estimated 4.3 million British men were obese - defined as having a body mass index of 30 or above.