Nearly twice as many women as men develop cancer as a result of obesity, official research shows.
A study found excess fat causes more than 20,000 cases a year in Britain, the highest estimate yet of the toll of the obesity epidemic.
Women made up 13,000 of those – the equivalent of 8.2 per cent of all female cancer cases diagnosed in 2012.
Around 7,200 were men, accounting for 4.4 per cent of all male cases.
Globally, 500,000 cancer cases could be attributed to patients being overweight, the World Health Organisation found.
In a league table of 176 nations compiled using the study data, British women came 38th. Top of the list was Barbados, where 12.7 per cent of female cancer cases were blamed on obesity.
Previous research has shown the risk of cancer often rises in tandem with weight, or body mass index (BMI).
Of the 13,000 British women with cancer that was caused by obesity, 5,269 had postmenopausal breast cancer.
This is a common form of the disease, and only around 10 per cent of all cases of this cancer are caused by fat.
But in some other types, obesity caused a much higher proportion of cases. For gallbladder cancer, the figure was 50 per cent. Since it is rare, however, that equated to only 272 cases.
Obesity was also a major factor in cancers of the oesophagus, colon, rectum, kidney, pancreas, ovary and womb lining.
While British men did better than British women, they fared worse relative to other countries.
With 4.4 per cent of cancers tied to obesity, they were joint fourth with men from Malta, behind only the Czech Republic (5.5 per cent), and Jordan and Argentina (both 4.5 per cent).
That is worse than the US, where only 3.5 per cent of cancers in men were the result of fat.
Obesity causes 5.2 per cent of cancers in developed countries, said the study by the International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organisation.
Dr Melina Arnold, one of its authors, said: ‘Women are disproportionately affected by obesity-related cancers.
‘For postmenopausal breast cancer, the most common cancer in women worldwide, the study suggests that 10 per cent of these cancers could have been prevented by having a healthy body weight.’
Experts say if Britons continue to pile on the pounds, it will lead to 4,000 extra cases a year by 2026.
Dr Kate Allen, of World Cancer Research Fund International, which contributed to the study, said: ‘These stark figures highlight just how serious the problem of obesity is. If we don’t start confronting the problem of weight, this situation will only get worse.’
The study shows that a quarter of all cancers attributable to obesity could have been prevented if populations had the same average BMI today that they had 30 years ago.
Christopher Wild, director of the IARC, said: ‘The number of cancers linked to obesity and overweight is expected to rise globally along with economic development.
‘This stresses the importance of putting in place efficient weight control measures, to curb the high number of cancers associated with excess body weight and to avoid the problems faced by rich countries being repeated in those now undergoing rapid development.’