A pair of doctors have revealed a simple trick that could be a better gauge of someone's health than the body mass index (BMI). Dr Clare Bailey Mosley, wife of the late Dr Michael Mosley, teamed up with their son Dr Jack Mosley on Instagram.

They discussed a 'quick and easy' method to evaluate your metabolic health - essentially, how your body processes things like fats and sugar. This plays a pivotal role in maintaining overall wellness and warding off chronic diseases.

Several factors contribute to metabolic health, including blood sugar levels, blood pressure, cholesterol and triglycerides, and waist circumference. Making positive changes to your metabolic health - regardless of age - can lower your risk of chronic diseases and enhance your overall well-being.

Poor metabolic health can lead to metabolic syndrome - a collection of conditions, including increased blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol or triglyceride levels. Metabolic syndrome significantly heightens the risk of heart disease, stroke, and diabetes.

It is vital to address the root causes of metabolic syndrome and make lifestyle alterations to prevent these conditions from progressing, reports Bristol Live.

In a video, the two doctors refer to something known as the string test. This involves taking a piece of string, standing on one end, and extending it so it matches your height. You then fold it in the middle, so it is half your height. You then wrap it around your waist.

If the ends meet, this is a good sign, but if they do not then it means you are more likely to have metabolic issues. "Did you know that the string test is a better measure of your metabolic health than BMI?" Dr Bailey-Mosley asks. "That is surprising to a lot of people."

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Dr Jack Mosley adds: "So the issues with BMI is it doesn't account for your muscle mass, but it also doesn't account for distribution of fat. One of the fats that we are more concerned about is your visceral fat. And this is a fat around your midriff.

"This is the fat that we are more concerned about and it's not about shaming anyone but it is actually quite important."

He added on Instagram: "The string test is a quick and easy way to give a rough idea of your metabolic health."

The fundamental principle is that your waistline should measure less than half your height, otherwise you could face an elevated risk of cardio-metabolic conditions, including heart disease, diabetes and high blood pressure. In many respects it serves as a more useful screening method than BMI, which fails to consider fat distribution or muscle composition.

To calculate your BMI, divide your weight in kilogrammes by your height in metres squared. Alternatively, you can use the NHS calculator here.