Overweight people are at a significantly higher risk of developing a range of common cancers, according to a new study.
In the study, carried out at the Washington University School of Medicine in the US, researchers analysed data from around the world on obesity, weight gain and weight loss in relation to cancers of the breast, pancreas, kidney, colon, prostate, oesophagus and endometrium, which is the lining of the womb.
"Most people associate high body weight with conditions like diabetes and heart disease, and a lot of people are not aware of the links between body weight and cancer," the Telegraph quoted Ed Yong, health information manager at Cancer Research UK, as saying.
"If you look at these cancers, they include two of the most common, breast and colon, and some which have very low survival rates, pancreatic and oesophagus. So body weight has a substantial impact on cancers that are common and those that are difficult to treat," Yong added.
During the study, researchers found that the cancer that emerged, as having the clearest link to weight gain was breast cancer in postmenopausal women.
They found that the risk of developing the disease increased by five per cent with every five kilograms of weight gained.
On contrary, women who lost weight were at a significantly lower risk of the disease. According to researchers, this may be because weight loss lowers oestrogen levels.
Study into colon cancer found that men who put on six kilograms or more in weight ran twice the risk of contracting the disease as men who lost two kilograms or more.
Those who gained 21 kilograms or more after reaching the age of 20 had a 60 per cent increased risk compared to men who have gained less than five kilograms.
According to researchers, weight loss and increased activity reduces circulating levels of insulin, which may help to prevent the cancer from developing.
During the study, it was found that a BMI increase of one, after the age of 20, gives a 14 per cent increased risk of oesophageal cancer. Those with a BMI increase of more than eight ran a threefold risk of contracting the cancer.
A person whose BMI increases by five runs a 14 per cent increased risk of pancreatic cancer, a 31 per cent increased risk of kidney cancer, and, among women, a 52 per cent increased risk of endometrial cancer.
Links between prostate cancer and obesity were less clear. However, men who put on more than 10 per cent of their body weight and had a BMI greater than 24.4 were twice as likely to develop prostate cancer as men with a lower BMI.
The study is published in the British Journal of Cancer.