Over 100,000 types of cancers are caused by obesity, according to an American study.

Excess body fat makes a person vulnerable to cancer by increasing the amount of hormones like estrogen circulating in the body and disrupting how the body processes insulin, which is linked to higher risk of cancer. It also triggers low-grade inflammation in the body, which is increasingly being found to play a role in cancer.

Researchers from American Institute for Cancer Research suggest that people should maintain a normal body weight and remain physically active throughout life. Weight gain after a cancer diagnosis is also likely to affect the outcome, say researchers.

"An increasing number of studies suggest that regular physical activity improves cancer survival, even among survivors who are overweight or obese," the Independent quoted AICR researchers as saying.

"Public awareness of the link between obesity and cancer risk is alarmingly low," said Alice Bender, MS, RD, Nutrition Communications Manager at AICR. We are working towards a day when obesity is right up there with tobacco in the public eye," Bender added.

The AICR estimates show that excess body fat is linked to 49 per cent of endometrial cancers , 35 per cent of esophageal cancers 28 per cent of pancreatic cancers, 24 per cent of kidney cancers, 21 per cent of gallbladder cancers, 17 per cent of breast cancers and 9 per cent of colorectal cancers.