Being overweight increases your risk for various health problems, including heart disease, high blood pressure, high cholesterol, and high blood sugar.
Earlier, evidence showed that excess body weight can contribute to causing as many as five cancers - adenocarcinoma of the esophagus; colorectal cancer; breast cancer in postmenopausal women; and uterine and kidney cancers.
Now, a review of more than a thousand studies has found solid evidence that being overweight or obese increases the risk for eight more forms of cancer including stomach, liver, gall bladder, pancreas, ovary, meningioma -- a type of brain tumour -- thyroid cancer and the blood cancer multiple myeloma.
The findings showed that for most of the cancers on the newly expanded list, the higher the body-mass index, or BMI, the greater was the risk of developing cancers.
"The burden of cancer due to being overweight or obese is more extensive than what has been assumed," said Graham Colditz, cancer prevention expert at Washington University.
"Many of the newly-identified cancers linked to excess weight haven't been on people's radar screens as having a weight component," Colditz added.
In addition, the cancer risks associated with excess weight were similar for men and women and were also consistent across geographic regions -- North America, Europe, Asia and the Middle East.
Excess fat leads to an overproduction of estrogen, testosterone and insulin, and promotes inflammation, all of which can drive cancer growth.
The study could have a significant bearing on the global population out of which an estimated 640 million adults and 110 million children are obese, said the study.
Limiting weight gain over the decades could help to reduce the risk of these cancers.
Moreover, lifestyle factors such as eating a healthy diet, maintaining a healthy weight and exercising, in addition to not smoking, can have a significant impact on reducing cancer risk, the researchers said.
"Rather than getting discouraged and giving up, those struggling to take off weight could instead focus on avoiding more weight gain," Colditz noted, warning "this is another wake-up call. It's time to take our health and our diets seriously".
The results are based on a review of more than 1,000 studies of excess weight and cancer risk analysed by the World Health Organisation's International Agency for Cancer on Research (IARC), in France.
The findings have been published in The New England Journal of Medicine.
(With agency input)