Experts have revealed that a simple tape measure can help you calculate obesity better than the lengthy and often confusing current body mass index (BMI).

Dr Jude Oben, from the Obesity Action Campaign, told Sky News that measuring waist size was a more accurate assessment of someone’s fat and less “tedious” than calculating BMI.

The fat inside your abdomen is a good indicator of your metabolic risk, and a tape measure can do the measuring, he said.

Oben said that men and women should keep their waist – measured at the level of the belly-button – below 35.5 inches and 31.5 inches respectively.