Previous research he conducted found about 75 percent of men and 80 percent of women aged 18 and over have thigh girths below the 'cut-off' suggested in the paper.

Surtees and his colleagues studied more than 20,000 people aged 41 to 80 over an eight-and-a-half-year period to see if they could find a link between depression and stroke.

China has nearly 167 million people aged over 60 and one million over 80.