But new research suggests having just four extra inches (11cm) than average on your waist increases the risk of many cancers by 13%.
The average woman in the UK has a waist of 34 inches (86.3cm), while men average at 38 inches (96.5cm).
Being overweight or obese is linked to 13 types of cancer, including breast, bowel, stomach, liver, gallbladder, pancreas, womb, ovary and kidney cancer.
The research, published in the British Journal of Cancer, also shows that for bowel cancer, adding around three inches (8cm) to the hips is linked to an increased risk of 15%.
Scientists at the International Agency for Research on Cancer showed that three different measurements of body size, BMI, waist circumference and waist to hip ratio all predicted similar obesity-related cancer risk in older adults.
The study combined data from around 43,000 participants and after a 12-year follow up, more than 1,600 people were diagnosed with an obesity-related cancer.
Dr Heinz Freisling, lead study author, said: “Our findings show that both BMI and where body fat is carried on the body can be good indicators of obesity-related cancer risk. Specifically, fat carried around the waist may be important for certain cancers, but requires further investigation.
“To better reflect the underlying biology at play, we think it’s important to study more than just BMI when looking at cancer risk. And our research adds further understanding to how people’s body shape could increase their risk.”
Dr Julie Sharp, Cancer Research UK’s head of health information, said: “This study further highlights that however you measure it being overweight or obese can increase the risk of developing certain cancers, including breast and bowel.
“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 keeping physically active that you can stick with in the long term can help you get to a healthy weight - and stay there.”