For decades, the Body Mass Index (BMI) has been used to determine a person’s health risks based on their size – but scientists now think they have found a better way to measure your heart’s health.
While BMI uses a person’s height and weight to show whether they are over or underweight, the new measurement compares a person’s height with their waist size.
Researchers say using the waist instead of the weight is more accurate because the BMI measurement does not take into account that some of your weight could be muscle, which is heavier than fat.
This means that, by using the BMI system, some elite athletes could technically be classed as overweight or obese.
Professor Alan Nevill said, “By dividing a person’s waist ratio by the square root of their height, we are able to give a reading that works for everyone, independent of how tall or short they are.”
Professor Nevill and his team ran a trial with 4,700 people, where the waist size measurement was found to be the most accurate indicator of cardio-metabolic health.
Using the new system, someone who is 5ft2in would be at risk with a 36in waist. Meanwhile, at 6ft1in, a 36in waist is fine but a 39in waist is the point at which developing heart disease becomes a real risk.
Professor Nevill added, “BMI is a measure of excess weight, but it cannot differentiate between muscle weight and fat weight.
“Waist-to-height ratio is the best way of identifying whether someone is likely to develop heart disease.”
However, the study also found that people who did at least 150 minutes of exercise per week are at a much lower risk of heart problems, regardless of weight.
The research was published in the Scandinavian Journal of Medicine and Science in Sports, where the team detailed how they monitored heart rate, oxygen intake, blood pressure, blood sugar and cholesterol of 4,763 people working out on a treadmill.
Using these figures, they assigned each person a “cardio-metabolic risk score” and found that their waist-to-height ratio correlated strongly with the cardio-metabolic risk scores – much more strongly than participants’ BMI scores did.