Women put at risk of early death because of mistaken reliance on BMI by doctors, study suggests

The size of the waist is also an important factor in health, research finds

Over-reliance on BMI means opportunities are missed to head off life-threatening diseases (Getty Images/iStockphoto)

Women who think they are a healthy weight because their body mass index (BMI) is within the normal range may unwittingly be at higher risk of early death because of their waist size, a new study suggests.

Research indicates that some people thought to be a normal weight could unknowingly be at high risk for obesity-related health issues.

Current guidelines state that doctors only need to take patients’ BMI into consideration when assessing the probability they will fall prey to such issues, which include heart disease and cancer.

Researchers found this means not enough attention is paid to the crucial factor of excess body weight stored around the middle of the body, known as central fat.

They found that this “missed opportunity” could not only mean life-threatening illnesses go undiagnosed before it is too late, but also some women are given a mistaken impression that they are fit and healthy.

Wei Bao, professor of epidemiology at the University of Iowa College of Public Health, said: “We should encourage physicians to look not only at body weight but also body shape when assessing a patient’s health risks.”

The study, published in the American Medical Association’s Jama Network Open, tracked more than 156,000 post-menopausal women aged between 50 and 79 in the 24-year period to 2017.

Using data from the Women’s Health Initiative, it found that women with a “healthy” BMI score but a large waist were 31 per cent more likely to die within the study window.

This means that women with a greater waist circumference were slightly more prone to a life-threatening condition, as those with an obese BMI score.

A waist measurement of 35 inches in women was identified as the threshold above which the risk of falling ill may increase.

Cardiovascular disease and cancers linked to obesity were the primary causes of death among people who had a normal BMI but a high waist size.

The findings also showed the ratio of muscle to fat – not accounted for in the BMI measurement – should be taken into account.

Prof Bao said: “People with normal weight based on BMI, regardless of their central obesity, were generally considered normal in clinical practice according to current guidelines.

“This could lead to a missed opportunity for risk evaluation and intervention programmes in this high-risk subgroup.”

The researchers acknowledge several limitations in their study, including that they only looked at older post-menopausal women, and had to rely on waist circumference as they did not have imaging data of the adipose tissue, or fat.

Agencies contributed to this report