A new report warns that one in five cancer deaths is caused by obesity.
The alert came at the world’s biggest conference on cancer, which sounded the warning that obesity is killing tens of thousands a year in western nations - and it will replace tobacco as the leading preventable cause of the disease.
Jennifer Ligibel of the Dana-Farber Cancer Institute at Harvard University told the American Society of Clinical Oncology in Chicago: “The average weight of our citizens is increasing dramatically.
“We’ve really got a critical mass of evidence where we see this relationship, the heavier people are more at risk.
“I think people are aware that being overweight increases the risk of heart disease and diabetes but not that it increases the risk of cancer and their risk of dying from cancer.
“It’s the case with breast cancer, prostate cancer, cancer of the colon and all the gynaecological cancers.”
Smoking is thought to be responsible for a quarter of cancer deaths and Dr Ligibel said obesity could surpass that figure in 10 to 15 years as the population gets fatter while giving up cigarettes.