1252 GMT January 26, 2020
Cancer Research UK says bowel, kidney, ovarian and liver cancers are more likely to have been caused by being overweight than by smoking tobacco, BBC wrote.
It said millions are at risk of cancer because of their weight and that obese people outnumber smokers two to one.
It comes as Tory leadership contender Boris Johnson vowed not to extend the sugar tax without a review.
When asked about plans to extend the so-called ‘sugar tax’ on soft drinks to milkshakes, Johnson mocked his own weight and said he was ‘very, very reluctant’ to impose taxes that ‘clobber those who can least afford it’.
He suggested we "encourage people to walk, cycle and generally do more exercise".
Meanwhile, Cancer Research UK's new billboard campaign, which highlights the obesity-cancer risk, has been criticized for fat-shaming.
It is not the first time the charity has been accused of fat-shaming.
In February, comedian and campaigner Sofie Hagen took to Twitter to criticize the campaign.
Cancer Research UK said it is not about blaming people for being overweight.
Nor is it suggesting that smoking and obesity are directly comparable in terms of cancer risk. Both increase a person's risk.
Smoking remains the UK's leading preventable cause of cancer overall. Obesity ranks second, said Cancer Research UK.
But while smoking rates are decreasing, obesity is increasing, which health experts agree is concerning.
About a third of UK adults are obese.
In the UK, there are about:
● 13.4 million obese adults who do not smoke.
● 6.3 million adult smokers who are not obese.
● 1.5 million obese adult smokers
While the link between obesity and cancer is well established, the biological mechanisms behind it are not yet fully understood.
Fat cells make extra hormones and growth factors that tell cells in the body to divide more often. This increases the chance of cancerous cells being made.
Physical activity probably plays a role too, experts say.
Being overweight or obese does not mean a person will definitely develop cancer but it does raise their risk.
And this risk is higher the more weight a person gains and the longer they are overweight.
According to Cancer Research UK, 13 different cancers are linked to obesity: Breast (in women after the menopause), bowel, pancreatic, esophageal (food pipe), liver, kidney, upper stomach, gallbladder, womb, ovarian, thyroid, multiple myeloma (blood cancer), meningioma (brain cancer).
The link between obesity and cancer is in adults only, although a healthy weight is important for children too.
Each year in the UK, the charity said, excess weight causes about:
● 1,900 more cases of bowel cancer than smoking
● 1,400 more cases of kidney cancer
● 460 more cases of ovarian cancer
● 180 more cases of liver cancer
Professor Linda Bauld, Cancer Research UK's prevention expert, said the government should do more to tackle the UK's obesity problem.
The government had been slow to restrict unhealthy food and drink ads, the British Medical Association said.
"While we are very much aware of the health risks associated with smoking, less effort has been thrown behind tackling obesity, which is now a major cause of cancer," it said,
The National Health Service (NHS) England chief executive Simon Stevens said: "The NHS can't win the 'battle against the bulge' on its own.
"Families, food businesses and government all need to play their part if we're to avoid copying America's damaging and costly example."