Piling on the pounds over several decades increases the risk of obesity-related cancers in men by 50 per cent and in women by almost 20 per cent, research has shown.
British scientists looked at the link between obesity and cancer in around 300,000 Americans – who were monitored between the ages of 18 and 65.
During that time, some people gained little weight while others became “morbidly” obese – meaning they were so fat it endangered their health.
The population was then followed for an average of 15 more years while cancer rates were recorded.
Men whose Body Mass Index (BMI) rose from around 22 to 27 had a 50 per cent increased risk of developing obesity-related cancer compared with men who stayed within a healthy weight range.
Women who went from a BMI of 23 to around 32 experienced a 17 per cent increase in risk. BMI is a measurement that relates height and weight.
Being overweight or obese is linked to a wide range of cancers – including bowel, breast and pancreatic cancer.
Several obesity-related cancers, such as womb and ovarian cancer, only affect women.
Lead scientist Dr Hannah Lennon, from the University of Manchester, said: “This research shows how important it is to look at weight gain over a person’s lifetime – to give a clearer picture of cancer risk through life compared to assessing someone’s BMI at a single point.
It could help identify people who would benefit the most from taking action to control their weight before any health problems arise, including a cancer diagnosis.”
The findings were presented at the National Cancer Research Institute’s (NCRI) Cancer Conference in Liverpool.
Sir Harpal Kumar, chief executive of Cancer Research UK – which funded the study, said taking a longer-term look at weight gain and cancer was “really interesting”.“It’s important that people are informed about ways to reduce their risk of cancer. And while there are no guarantees against the disease, keeping a healthy weight can help you stack the odds in your favour and has lots of other benefits, too.
“Making small changes in eating, drinking and taking exercise that you can stick with in the long term is a good way to get to a healthy weight – and stay there.”
Dr Karen Kennedy, director of the NCRI, said: “This study provides a deeper understanding of the health implications caused by the obesity epidemic.”