Significant weight gain over a number of years can increase a person's risk of obesity-related cancers by over 50%, a new study has found.

UK researchers looked at more than 300,000 people in America over a 15-year period. All were aged between 18 and 65 and while some had gained a little weight during the study period, others had become morbidly obese.

The researchers charted the participants' body mass index (BMI) and found that men who went from a BMI of 22, which is in the healthy weight range, to a BMI of 27, which is considered overweight, saw their risk of developing an obesity-related cancer jump by 50%.

Men who went from the overweight range to morbidly obese saw their risk jump by 53%.

Meanwhile, women who went from a BMI of 23 (healthy) to 32 (obese) were found to have a 17% increased risk of developing an obesity-related cancer compared to women who remained in the healthy range.

"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.

"This study could also be really useful in public health. 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," commented the study's lead author, Dr Hannah Lennon, of the University of Manchester.

The study was funded by Cancer Research UK and according to its CEO, Sir Harpal Kumar, ‘while there are no guarantees against the disease, keeping a healthy weight can help you stack the odds in your favour'.

Details of these findings were presented at the National Cancer Research Institute's Cancer Conference in Liverpool this week.