Being obese is strongly linked to 11 different cancers, British scientists have confirmed.
A new study published in the British Medical Journal (BMJ) found that being obese increases the risk of multiple myeloma and cancer of the oesophagus, stomach, bowel, rectum, biliary tract system (liver, gall bladder and bile duct), pancreas, postmenopausal breast, womb, ovary and kidney.
Researchers also found evidence of an association with other cancers but said existing studies did not provide a strong enough link.
The World Cancer Research Fund (WCRF), which funded the study, estimates about 25,000 cancer cases could be prevented in the UK every year if everyone was a healthy weight.
The new research was led by Maria Kyrgiou and Kostas Tsilidis from Imperial College London.
The team identified 204 studies that looked at the link between body mass index, weight gain, and waist circumference, and 36 cancers and their subtypes.
But only a few studies were supported by strong evidence.
The WCRF has previously identified most of the cancers as being linked to obesity, although multiple myeloma is new on the list.
"This research, which we have funded, further emphasises the huge role that obesity plays in increasing cancer risk," said Dr Panagiota Mitrou, the director of research funding at WCRF.
"After not smoking, being a healthy weight is the most important thing people can do to reduce their cancer risk.
"With obesity rates continuing to rise in the UK and worldwide, it is incredibly important that tackling the obesity epidemic be made an urgent priority."
The Obesity Health Alliance, a coalition of more than 35 health charities, campaign groups and Royal Medical Colleges, said: "Obesity is a serious health concern and on top of being linked to major cancers, can also increase the risk of type-2 diabetes, heart and liver disease and mental health problems.
"This is why it's so important to introduce measures like the soft drinks industry levy, reduce sugar, saturated fat and salt from everyday foods, and close loopholes to protect children from junk food marketing."