New analysis from Cancer Research UK has found that excess weight causes more cases of certain cancers than smoking, as the number of people who are obese now outnumbers those who smoke two to one in the UK.

According to the charity, almost one third of UK adults are obese, and being overweight or obese is now the leading cause of four different types of cancer, despite the fact that smoking is still the biggest preventable cause of cancer and carries a much higher risk of the disease.

The data shows that excess weight causes around 1,900 more cases of bowel cancer than smoking in the UK each year, while the same “worrying pattern” is seen in cancer in the kidneys (1,400 more cases caused by excess weight than by smoking each year), ovaries (460) and liver (180), it warned.

"As smoking rates fall and obesity rates rise, we can clearly see the impact on a national health crisis when the government puts policies in place – and when it puts its head in the sand,” said Michelle Mitchell, Cancer Research UK’s chief executive.

"Our children could be a smoke-free generation, but we’ve hit a devastating record high for childhood obesity, and now we need urgent government intervention to end the epidemic. They still have a chance to save lives.”

The charity is urging the government to “act on its ambition to halve childhood obesity rates by 2030 and introduce a 9pm watershed for junk food adverts on TV and online”, alongside other measures designed to encourage consumption of healthier food and drinks.

It has also launched a new nationwide campaign this week to boost public awareness of the link between obesity and cancer.