Harry Styles bullet coffee diet keeps him slim

London: One Direction member Harry Styles says the reason for him being slim is a concoction known as 'bullet coffee'.

The 21-year-old singer, who boasts a waist of just 26 inches, replaces his meals with coffee mixed with butter and coconut oil, reported Mirror.

"Bullet coffee. It's black coffee with a spoonful of butter in it and a spoonful of coconut oil, all mixed up together. I've been on it for two days. You don't get hungry," Styles said.

Apart from the extreme method, Styles is also into meditation and Pilates, and stays active by boxing and running.