Obese women are at 40 per cent greater risk of developing a weight-related cancer than those who are slimmer, experts warn today.
Researchers from the charity Cancer Research UK say obesity increases a woman’s risk of at least seven different types of cancer.
And they say more women in Yorkshire are at risk due to higher rates of obesity in the region.
Figures from the charity reveal as many as 18,000 women each year develop cancer because they are obese or overweight.
In a group of 1,000 obese women, 274 will be diagnosed with a weight-related cancer, compared with 194 healthy weight women, an increased risk of weight-related cancer over a lifetime of 41 per cent.
In Yorkshire, around 28 per cent of women are obese compared with 25 per cent in the UK.
Obesity-related malignancies include bowel, post-menopausal breast, gallbladder, womb, kidney, pancreatic and oesophageal cancers.
The increased risks of cancers of the oesophagus and womb due to obesity are as much as 130 per cent, the risk of gallbladder cancer is double and of kidney cancer is up 78 per cent.
Extra risks of breast, bowel and pancreatic cancers are up by between 25-32 per cent.
Scientists say there are different ways that obesity could increase the risk of cancer.
One possibility is that it is linked to a fat cell’s production of hormones in particular oestrogen.
This hormone is thought to fuel the development of cancer.
Julie Sharp, head of health information at Cancer Research UK, said: “We know that our cancer risk depends on a combination of our genes, our environment and other aspects of our lives, many of which we can control - helping people understand how they can reduce their risk of developing cancer in the first place remains crucial in tackling the disease.
“Lifestyle changes, like not smoking, keeping a healthy weight, eating a healthy diet and cutting back on alcohol – are the big opportunities for us all to personally reduce our cancer risk.
“Making these changes is not a guarantee against cancer, but it stacks the odds in our favour.”
Women with a body-mass index of between 25 and 29 are overweight. Anyone above that is obese.
Nicki Embleton, spokesman for the charity in Yorkshire, said: “Losing weight isn’t easy, but women don’t have to join a gym and run miles every day or give up their favourite food forever.
“Just making small changes that can be maintained in the long term can have a real impact.”
The charity is urging women to begin healthier lifestyles by taking part in its Race for Life events across the region between May and July.
Millions of pounds are raised each year for life-saving research from the women-only events in a series of 5k, 10k and Pretty Muddy races.
She added: “Signing up to take part in Race for Life is a great way for women of all shapes and sizes to commit to get a little more active.
“Taking part is not about being fit or fast and participants can choose to walk, jog, or run around the course.
“The atmosphere is incredibly supportive and pledging to take part, alongside thousands of like-minded women, is a great motivation to get fitter as well as raise money for life-saving research.”
To enter Race for Life go to raceforlife.org or call 0300 123 0770.