More than half of British women have waists that are larger than the recommended healthy size, experts say.
Researchers from the charity Nuffield Health say overweight women risk an increased chance of heart disease, type 2 diabetes, infertility and cancer.
The researchers found the average waist measurement for women is 84.9cm (33.43in), compared with the healthy size of 80cm (31.49in).
Nuffield Health's Dr Davina Deniszczyc said it was a "worrying problem."
Dr Deniszczyc, professional head of physicians and diagnostics at Nuffield Health, said: "Fat being stored around the waist can contribute to significant health issues, such as breast cancer and infertility."
Nuffield Health examined data from more than 30,000 women and found 57% had a waist larger than the healthy size.
It said women in the north of England have the largest waists, with an average circumference of 87cm, compared to 81.9cm in London.
Researchers also said 52.5% of the women have a body mass index (BMI) higher than the healthy range, while 16.2% were moderately or morbidly obese.
The BMI is calculated by taking your weight in kilograms and dividing it by your height in metres squared.
A BMI level measured between 25 and 29.9 means a person is regarded as overweight. If your BMI is over 30 then you are clinically obese.
Dr Deniszczyc said: "Whilst waist size may seem like a cosmetic issue, this isn't about women fitting into their skinny jeans. Rather, it's an important indicator of overall health and well-being, particularly when taken into account with other health measurements.
