What’s my risk of developing cancer if I'm overweight or obese?

Being overweight doesn’t mean that someone will definitely develop cancer. But if a person is overweight they are more likely to get cancer than if they are a healthy weight.

We can help stack the odds against cancer by losing weight or avoiding gaining more weight.

People keeping a healthy weight could prevent around 22,800 cases of cancer every year in the UK.

How can overweight and obesity cause cancer?

Extra fat in the body doesn’t just sit there, its active, sending out signals to the rest of your body. These signals can tell cells in our body to divide more often, which can lead to cancer.

Scroll down to find out more about the science…

What types of cancer are caused by excess weight?

Breast (in women after the menopause), bowel, womb, oesophageal (food pipe), pancreatic, kidney, liver, upper stomach (gastric cardia), gallbladder, ovarian, thyroid, myeloma (a type of blood cancer), and meningioma (a type of brain tumour).

This includes 2 of the most common types of cancer – breast and bowel cancers - and 3 of the hardest to treat – pancreatic, oesophageal and gallbladder cancers.

Is the link the same in children?

No. The link between overweight and obesity and cancer is only in adulthood. But a healthy body weight is important for children too.

One in 5 children are overweight or obese before they begin primary school, and even more by the time they leave.

Children who are obese are around 5 times more likely to grow into adults who are obese.

What does the research show?

Consistent results from decades of research involving millions of people show the link between oveweight and obesity and cancer and means we can confidently rule out other explanations (such as chance or other lifestyle factors).

The risk increases the more weight is gained, so we can be more sure the link is real (this is called a dose-response relationship). And there are good explanations for how extra fat cells in the body could cause cancer.

International organisations like the International Agency for Research on Cancer and the World Cancer Research Fund agree.

A person’s risk of cancer depends on lots of different factors, including things you can’t change like your age and genes. Other things that can cause cancer, whether that’s obesity, tobacco or the sun, increase a person’s risk of cancer, but do not mean that person will definitely develop cancer.

But when we look at a whole population, these factors cause more people to develop cancer.