How and when did the term ‘size zero’ come into use?

‘Size zero’ was first used in 1966 for British supermodel Twiggy, who had a fragile figure. Now, ‘size zero’ is a women’s clothing size in the US system, equivalent to a UK size 4, with a waist measurement of 23 inches, the average girth of an 8-year-old girl. It is a petite size for women with a 32-inch bust, 23-inch waist and 32-inch hips, and is often linked to anorexia nervosa and bulimia.