Study: Waist-to-hip ratio should replace BMI to measure healthy weight

Measuring waist-to-hip ratio, not body mass index, is a better indicator of healthy weight and may better predict early death, according to a new study. Photo by PublicDomainPictures/Pixabay

Sept. 21 (UPI) — New research suggests that waist-to-hip ratio, not body mass index, is a better measure of healthy weight and may predict early death better than BMI.

The researchers urge the new method to replace BMI, which the Centers for Disease Control and Prevention has called “an easy and inexpensive tool” because this calculation only requires a person’s height and weight.

But the researchers said waist-to-hip ratio is also a “quick and easy measurement,” calculated by dividing waist circumference by hip circumference.

Their work is being presented this week at the annual meeting of the European Association for the Study of Diabetes in Stockholm.

BMI is calculated by taking a person’s weight in kilograms and dividing it by the square of their height in meters, with a BMI of 18.5 to 24.9 considered healthy. But that measure doesn’t take fat distribution into account, the researchers said.

“It does not take into account where fat is stored, whether it accumulates around the hips or the waist. As a result, BMI does not reliably predict the risk of disease or mortality,” said Irfan Khan, medical student at Cork University. College of Medicine and Health in Cork, Ireland, who conducted the research with colleagues in Canada.

This means that a person who has accumulated fat around the waist will have the same BMI as someone of the same age and height who stores fat around the hips, despite the health risks of abdominal fat, the researchers said .

Khan said waist-to-hip ratio better reflects levels of abdominal fat, including visceral fat, which surrounds organs inside the body and increases the risk of a range of medical conditions.

A more accurate measure of healthy body shape “can make a significant difference in ill health and deaths from type 2 diabetes, heart disease, some cancers and many other conditions,” he said.

According to Khan, the message is simple: the lower a person’s waist-to-hip ratio, the lower the risk of mortality.

Waist-to-hip ratio is “a stronger, more robust measurement” compared to BMI, he told UPI in an email.

“Rather than aiming for a specific BMI target, which may or may not be beneficial depending on individual body composition, aim for a lower target. [waist-to-hip ratio] it will always lead to a lower death rate,” he said.

At first, the researchers wanted to determine whether waist-to-hip ratio, or fat mass index, would more reliably predict mortality in different fat distributions.

The fat mass index is calculated by dividing the fat weight in kilograms by the height in meters squared; BMI takes into account a person’s total weight in the measurement.

First, study researchers analyzed data from UK biobank participants who had genes known to predispose them to weight gain and obesity. Their analysis indicated that higher levels of fat caused an increase in mortality, rather than just being correlated with it, the statement said.

They then applied information about genes associated with the three measures (BMI, waist-to-hip ratio, and body fat mass index) to data from approximately 25,000 white men and women whose health had been tracked as part of from the UK Biobank study. until their death, and a similar number of “age, sex and genetic ancestry” controls.

Despite using the genetically determined waist-to-hip ratio for their analysis, the scientists said their findings apply equally to conventional waist and hip measurement.

The researchers found that the risk of early death was lowest for those with the lowest waist-to-hip ratio and then rose steadily with increasing waist-to-hip ratio.

Conversely, individuals with an extremely high or low BMI or body fat mass index had a higher risk of death compared to those with a moderate BMI or body fat mass index.

For example, each one-unit increase in waist-to-hip ratio increased the odds of premature death almost twice as much as a one-unit increase in BMI or body fat index.

The scientists also found that waist-to-hip ratio was more strongly associated with all-cause death than BMI or body fat index. This link was stronger in men than in women.

According to Khan, doctors may already have a tape measure for certain exams: such as measuring a patient’s apparent versus actual limb length, or measuring the size of the liver during abdominal or gastrointestinal exams.

“Waist and hip circumference is easy to measure in adults with a tape measure, so I don’t see why doctors shouldn’t carry a tape measure to do that as well,” he said.

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